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Contents Preface xiii To the Student xxiii Diagnostic Tests thomasmayerarchive.com 1 xxiv A Preview of Calculus 3 Functions and Models 11 1.1 Four Ways to Represent a Function 1.2 Mathematical Models: A Catalog of Essential Functions 12 1.3 New Functions from Old Functions 37 1.4 Graphing Calculators and Computers 46 1.5 Exponential Functions 1.6 Inverse Functions and Logarithms 1.7 Parametric Curves 52 61 71 Laboratory Project ■ Running Circles Around Circles Review Limits and Derivatives 83 89 2.1 The Tangent and Velocity Problems 2.2 The Limit of a Function 2.3 Calculating Limits Using the Limit Laws 2.4 Continuity 2.5 Limits Involving Infinity 2.6 Derivatives and Rates of Change 90 95 104 113 124 135 thomasmayerarchive.com Writing Project ■ Early Methods for Finding Tangents 2.7 The Derivative as a Function 146 2.8 What Does f ⬘ Say about f ? 158 Review 79 80 Principles of Problem Solving 2 25 145 164 Focus on Problem Solving 169 vii viii CONTENTS 3 Differentiation Rules 3.1 173 Derivatives of Polynomials and Exponential Functions Applied Project ■ Building a Better Roller Coaster 3.2 The Product and Quotient Rules 3.3 Derivatives of Trigonometric Functions 3.4 The Chain Rule 183 183 190 197 Laboratory Project ■ Bézier Curves 208 Applied Project ■ Where Should a Pilot Start Descent? 3.5 Implicit Differentiation 3.6 Inverse Trigonometric Functions and Their Derivatives 3.7 Derivatives of Logarithmic Functions thomasmayerarchive.com Discovery Project ■ 227 Rates of Change in the Natural and Social Sciences 3.9 Linear Approximations and Differentials 240 Laboratory Project ■ Taylor Polynomials 4 247 248 251 Applications of Differentiation 4.1 Related Rates 4.2 Maximum and Minimum Values 255 256 262 Applied Project ■ The Calculus of Rainbows 4.3 Derivatives and the Shapes of Curves 4.4 Graphing with Calculus and Calculators 4.5 Indeterminate Forms and l’Hospital’s Rule 270 271 282 290 Writing Project ■ The Origins of l’Hospital’s Rule 4.6 Optimization Problems 299 thomasmayerarchive.com Applied Project ■ The Shape of a Can 4.7 Newton’s Method 4.8 Antiderivatives Review 312 317 323 Focus on Problem Solving 327 216 221 Hyperbolic Functions Focus on Problem Solving 209 209 3.8 Review 174 311 299 228 CONTENTS 5 Integrals 331 5.1 Areas and Distances 332 5.2 The Definite Integral 343 5.3 Evaluating Definite Integrals Discovery Project 5.4 ■ 356 Area Functions 366 The Fundamental Theorem of Calculus 367 Writing Project ■ Newton, Leibniz, and the Invention of Calculus 5.5 The Substitution Rule 5.6 Integration by Parts 5.7 Additional Techniques of Integration 5.8 Integration Using Tables and Computer Algebra Systems 375 383 389 thomasmayerarchive.com Discovery Project ■ Patterns in Integrals 5.9 Approximate Integration 5.10 Improper Integrals Review 401 423 428 Applications of Integration 6.1 More About Areas 6.2 Volumes 431 432 438 Discovery Project ■ Rotating on a Slant 6.3 Volumes by Cylindrical Shells 6.4 Arc Length 455 Average Value of a Function Applied Project 6.6 448 449 Discovery Project ■ Arc Length Contest 6.5 400 413 Focus on Problem Solving 6 ■ 460 460 Where To Sit at the Movies Applications to Physics and Engineering 464 464 thomasmayerarchive.com Discovery Project ■ Complementary Coffee Cups 6.7 Applications to Economics and Biology 6.8 Probability Review 374 480 487 Focus on Problem Solving 491 476 475 394 ix x CONTENTS 7 Differential Equations 493 7.1 Modeling with Differential Equations 494 7.2 Direction Fields and Euler’s Method Separable Equations 508 499 7.3 Applied Project ■ How Fast Does a Tank Drain? Applied Project 7.4 ■ Which Is Faster, Going Up or Coming Down? Exponential Growth and Decay Courtesy of Frank O. Gehry 7.6 8 The Logistic Equation Predator-Prey Systems Review 547 530 540 Focus on Problem Solving 551 Infinite Sequences and Series 8.1 Sequences 529 553 554 Laboratory Project ■ Logistic Sequences 8.2 8.3 8.4 8.5 8.6 8.7 575 618 thomasmayerarchive.com Writing Project ■ How Newton Discovered the Binomial Series Applications of Taylor Polynomials Applied Project Review ■ 619 Radiation from the Stars 631 Vectors and the Geometry of Space 9.1 9.2 9.3 9.4 627 628 Focus on Problem Solving 9 thomasmayerarchive.com 564 Series 565 The Integral and Comparison Tests; Estimating Sums Other Convergence Tests 585 Power Series 592 Representations of Functions as Power Series 598 Taylor and Maclaurin Series 604 Laboratory Project ■ An Elusive Limit 8.8 Three-Dimensional Coordinate Systems Vectors 639 The Dot Product 648 The Cross Product 654 633 634 Discovery Project ■ The Geometry of a Tetrahedron 9.5 Equations of Lines and Planes 663 Laboratory Project ■ Putting 3D in Perspective 9.6 518 519 Applied Project ■ Calculus and Baseball 7.5 517 Functions and Surfaces 673 672 662 618 CONTENTS 9.7 Cylindrical and Spherical Coordinates Laboratory Project ■ Families of Surfaces Review 10 Vector Functions 10.2 Courtesy of Frank O. Gehry 10.3 10.4 691 693 Vector Functions and Space Curves 694 Derivatives and Integrals of Vector Functions 701 Arc Length and Curvature 707 Motion in Space: Velocity and Acceleration 716 Applied Project ■ Kepler’s Laws 10.5 Parametric Surfaces Review 733 11 Partial Derivatives 11.2 11.3 11.4 11.5 11.6 11.7 726 727 Focus on Problem Solving 11.1 687 688 Focus on Problem Solving 10.1 682 735 737 Functions of Several Variables 738 Limits and Continuity 749 Partial Derivatives 756 Tangent Planes and Linear Approximations 770 The Chain Rule 780 Directional Derivatives and the Gradient Vector 789 Maximum and Minimum Values 802 Applied Project ■ Designing a Dumpster 811 Courtesy of Frank O. Gehry Discovery Project ■ Quadratic Approximations and Critical Points 11.8 Lagrange Multipliers Applied Project 813 Rocket Science 820 Applied Project ■ Hydro-Turbine Optimization Review 822 Focus on Problem Solving 12 Multiple Integrals 12.1 thomasmayerarchive.com ■ 12.2 12.3 12.4 12.5 12.6 827 829 Double Integrals over Rectangles 830 Iterated Integrals 838 Double Integrals over General Regions 844 Double Integrals in Polar Coordinates 853 Applications of Double Integrals 858 Surface Area 868 821 812 xi xii CONTENTS 12.7 Triple Integrals 873 Discovery Project ■ Volumes of Hyperspheres 12.8 Triple Integrals in Cylindrical and Spherical Coordinates Applied Project ■ Discovery Project 12.9 Roller Derby ■ 13 Vector Calculus 13.2 13.3 13.4 13.5 13.6 thomasmayerarchive.com 13.7 The Intersection of Three Cylinders 13.9 903 905 Vector Fields 906 Line Integrals 913 The Fundamental Theorem for Line Integrals Green’s Theorem 934 Curl and Divergence 941 Surface Integrals 949 Stokes’ Theorem 960 The Divergence Theorem Summary 973 Review 974 967 Focus on Problem Solving 977 Appendixes A B C D E F G H I J 925 966 A1 Intervals, Inequalities, and Absolute Values A2 Coordinate Geometry A7 Trigonometry A17 Precise Definitions of Limits A26 A Few Proofs A36 Sigma Notation A41 Integration of Rational Functions by Partial Fractions Polar Coordinates A55 Complex Numbers A71 Answers to Odd-Numbered Exercises A80 Index A135 890 891 Writing Project ■ Three Men and Two Theorems 13.8 883 889 Change of Variables in Multiple Integrals Review 899 Focus on Problem Solving 13.1 883 A47 Preface When the first edition of this book appeared twelve years ago, a heated debate about calculus reform was taking place. Such issues as the use of technology, the relevance of rigor, and the role of discovery versus that of drill were causing deep splits in mathematics departments. Since then the rhetoric has calmed down somewhat as reformers and traditionalists have realized that they have a common goal: to enable students to understand and appreciate calculus. The first three editions were intended to be a synthesis of reform and traditional approaches to calculus instruction. In this fourth edition I continue to follow that path by emphasizing conceptual understanding through visual, verbal, numerical, and algebraic approaches. I aim to convey to the student both the practical power of calculus and the intrinsic beauty of the subject. The principal way in which this book differs from my more traditional calculus textbooks is that it is more streamlined. For instance, there is no complete chapter on techniques of integration; I don’t prove as many theorems (see the discussion on rigor on page xv); and the material on transcendental functions and on parametric equations is interwoven throughout the book instead of being treated in separate chapters. Instructors who prefer fuller coverage of traditional calculus topics should look at my books Calculus, Sixth Edition, and Calculus: Early Transcendentals, Sixth Edition. What’s New In the Fourth Edition? The changes have resulted from talking with my colleagues and students at the University of Toronto and from reading journals, as well as suggestions from users and reviewers. Here are some of the many improvements that I’ve incorporated into this edition: ■ At the beginning of the book there are four diagnostic tests, in Basic Algebra, Analytic Geometry, Functions, and Trigonometry. Answers are given and students who don’t do well are referred to where they should seek help (Appendixes, review sections of Chapter 1, and the website stewartcalculus.com). ■ The majority of examples now have titles. ■ Some material has been rewritten for greater clarity or for better motivation. See, for instance, the introduction to maximum and minimum values on pages 262–63 and the introduction to series on page 565. ■ New examples have been added and the solutions to some of the existing examples have been amplified. For instance, I added details to the solution of Example 2.3.10 because when I taught Section 2.3 last year I realized that students need more guidance when setting up inequalities for the Squeeze Theorem. ■ A number of pieces of art have been redrawn. ■ The data in examples and exercises have been updated to be more timely. ■ In response to requests of several users, the material motivating the derivative is briefer: The former sections 2.6 and 2.7 have been combined into a single section called Derivatives and Rates of Change. ■ The section on Rates of Change in the Natural and Social Sciences has been moved later in Chapter 3 (Section 3.8) in order to incorporate more differentiation rules. ■ Coverage of inverse trigonometric functions has been consolidated in a single dedicated section (3.6). xiii xiv PREFACE The former sections 4.6 and 4.7 have been merged into a single section, with a briefer treatment of optimization problems in business and economics. ■ There is now a full section on volumes by cylindrical shells (6.3). ■ Sections 8.7 and 8.8 have been merged into a single section. I had previously featured the binomial series in its own section to emphasize its importance. But I learned that some instructors were omitting that section, so I decided to incorporate binomial series into 8.7. ■ More than 25% of the exercises in each chapter are new. Here are a few of my favorites: 2.5.46, 2.5.49, 2.8.6–7, 3.3.50, 3.5.45– 48, 4.3.49–50, 5.2.47– 49, 8.2.35, 9.1.42, and 11.8.20–21. ■ There are also some good new problems in the Focus on Problem Solving sections. See, for instance, Problem 5 on page 252, Problems 17 and 18 on page 429, Problem 15 on page 492, Problem 13 on page 632, and Problem 9 on page 736. ■ The new project on page 475, Complementary Coffee Cups, comes from an article by Thomas Banchoff in which he wondered which of two coffee cups, whose convex and concave profiles fit together snugly, would hold more coffee. ■ Features Conceptual Exercises The most important way to foster conceptual understanding is through the problems that we assign. To that end I have devised various types of problems. Some exercise sets begin with requests to explain the meanings of the basic concepts of the section. (See, for instance, the first couple of exercises in Sections 2.2. 2.4, 2.5, 5.3, 8.2, 11.2, and 11.3. I often use them as a basis for classroom discussions.) Similarly, review sections begin with a Concept Check and a True-False Quiz. Other exercises test conceptual understanding through graphs or tables (see Exercises 1.7.22–25, 2.6.17, 2.7.33–44, 3.8.5–6, 5.2.47–49, 7.1.11–13, 8.7.2, 10.2.1–2, 10.3.33–37, 11.1.1–2, 11.1.9–18, 11.3.3–10, 11.6.1–2, 11.7.3–4, 12.1.5–10, 13.1.11–18, 13.2.15–16, and 13.3.1–2). Another type of exercise uses verbal description to test conceptual understanding (see Exercises 2.4.10, 2.7.54, 2.8.9, 2.8.13–14, and 5.10.55). I particularly value problems that combine and compare graphical, numerical, and algebraic approaches (see Exercises 2.5.38, 2.5.43–44, 3.8.25, and 7.5.2). Graded Exercise Sets Each exercise set is carefully graded, progressing from basic conceptual exercises and skill-development problems to more challenging problems involving applications and proofs. Real-World Data My assistants and I have spent a great deal of time looking in libraries, contacting companies and government agencies, and searching the Internet for interesting real-world data to introduce, motivate, and illustrate the concepts of calculus. As a result, many of the examples and exercises deal with functions defined by such numerical data or graphs. See, for instance, Figure 1 in Section 1.1 (seismograms from the Northridge earthquake), Exercise 5.1.14 (velocity of the space shuttle Endeavour), Figure 5 in Section 5.3 (San Francisco power consumption), Example 5 in Section 5.9 (data traffic on Internet links), and Example 3 in Section 9.6 (wave heights). Functions of two variables are illustrated by a table of values of the wind-chill index as a function of air temperature and wind speed (Example 1 in Section 11.1). Partial derivatives are introduced in Section 11.3 by examining a column in a table of values of the heat index (perceived air temperature) as a function of the actual temperature and the relative humidity. This example is pursued further in connection with linear approximations (Example 3 in Section 11.4). Directional derivatives are introduced in Section 11.6 by using a temperature contour map to estimate the rate of change of temperature at Reno in the direction of Las Vegas. Double integrals are used to estimate the average snowfall in Colorado on December 20–21, 2006 (Example 4 in Section 12.1). Vector fields are PREFACE xv introduced in Section 13.1 by depictions of actual velocity vector fields showing San Francisco Bay wind patterns. Projects One way of involving students and making them active learners is to have them work (perhaps in groups) on extended projects that give a feeling of substantial accomplishment when completed. Applied Projects involve applications that are designed to appeal to the imagination of students. The project after Section 3.1 asks students to design the first ascent and drop for a roller coaster. The project after Section 11.8 uses Lagrange multipliers to determine the masses of the three stages of a rocket so as to minimize the total mass while enabling the rocket to reach a desired velocity. Laboratory Projects involve technology; the project following Section 3.4 shows how to use Bézier curves to design shapes that represent letters for a laser printer. Writing Projects ask students to compare present-day methods with those of the founders of calculus—Fermat’s method for finding tangents, for instance. Suggested references are supplied. Discovery Projects anticipate results to be discussed later or cover optional topics (hyperbolic functions) or encourage discovery through pattern recognition (see the project following Section 5.8). Others explore aspects of geometry: tetrahedra (after Section 9.4), hyperspheres (after Section 12.7), and intersections of three cylinders (after Section 12.8). Additional projects can be found in the Instructor’s Guide (see, for instance, Group Exercise 5.1: Position from Samples) and also in the CalcLabs supplements. Rigor I include fewer proofs than in my more traditional books, but I think it is still worthwhile to expose students to the idea of proof and to make a clear distinction between a proof and a plausibility argument. The important thing, I think, is to show how to deduce something that seems less obvious from something that seems more obvious. A good example is the use of the Mean Value Theorem to prove the Evaluation Theorem (Part 2 of the Fundamental Theorem of Calculus). I have chosen, on the other hand, not to prove the convergence tests but rather to argue intuitively that they are true. Problem Solving Students usually have difficulties with problems for which there is no single well-defined procedure for obtaining the answer. I think nobody has improved very much on George Polya’s four-stage problem-solving strategy and, accordingly, I have included a version of his problem-solving principles at the end of Chapter 1. They are applied, both explicitly and implicitly, throughout the book. (The logo PS emphasizes some of the explicit occurrences.) After the other chapters I have placed sections called Focus on Problem Solving, which feature examples of how to tackle challenging calculus problems. In selecting the varied problems for these sections I kept in mind the following advice from David Hilbert: “A mathematical problem should be difficult in order to entice us, yet not inaccessible lest it mock our efforts.” When I put these challenging problems on assignments and tests I grade them in a different way. Here I reward a student significantly for ideas toward a solution and for recognizing which problem-solving principles are relevant. Technology The availability of technology makes it not less important but more important to understand clearly the concepts that underlie the images on the screen. But, when properly used, graphing calculators and computers are powerful tools for discovering and understanding those concepts. I assume that the student has access to either a graphing calculator or a computer algebra system. The icon ; indicates an exercise that definitely requires the use of such technology, but that is not to say that a graphing device can’t be used on the other exercises as well. The symbol CAS is reserved for problems in which the full resources of a computer algebra system (like Derive, Maple, Mathematica, or the TI-89/92) are required. But technology doesn’t make pencil and paper obsolete. Hand calculation and sketches are often preferable to technology for illustrating and reinforcing some concepts. Both instructors and students need to develop the ability to decide where the hand or the machine is appropriate. xvi PREFACE Tools for Enriching™ Calculus TEC is a companion to the text and is intended to enrich and complement its contents. (It is now accessible from the Internet at www.stewartcalculus.com.) Developed by Harvey Keynes, Dan Clegg, Hubert Hohn, and myself, TEC uses a discovery and exploratory approach. In sections of the book where technology is particularly appropriate, marginal icons direct students to TEC modules that provide a laboratory environment in which they can explore the topic in different ways and at different levels. Visuals are animations of figures in the text; Modules are more elaborate activities and include exercises. Instructors can choose to become involved at several different levels, ranging from simply encouraging students to use the Visuals and Modules for independent exploration, to assigning specific exercises from those included with each Module, or to creating additional exercises, labs, and projects that make use of the Visuals and Modules. TEC also includes Homework Hints for representative exercises (usually odd-numbered) in every section of the text, indicated by printing the exercise number in red. These hints are usually presented in the form of questions and try to imitate an effective teaching assistant by functioning as a silent tutor. They are constructed so as not to reveal any more of the actual solution than is minimally necessary to make further progress. Enhanced WebAssign Technology is having an impact on the way homework is assigned to students, particularly in large classes. The use of online homework is growing and its appeal depends on ease of use, grading precision, and reliability. With the fourth edition we have been working with the calculus community and WebAssign to develop an online homework system. Many of the exercises in each section are assignable as online homework, including free response, multiple choice, and multi-part formats. The system also includes Active Examples, in which students are guided in step-by-step tutorials through text examples, with links to the textbook and to video solutions. Website: www.stewartcalculus.com This website includes the following. ■ Algebra Review ■ Lies My Calculator and Computer Told Me ■ History of Mathematics, with links to the better historical websites ■ Additional Topics (complete with exercise sets): Trigonometric Integrals, Trigonometric Substitution, Strategy for Integration, Strategy for Testing Series, Fourier Series, Formulas for the Remainder Term in Taylor Series, Linear Differential Equations, Second-Order Linear Differential Equations, Nonhomogeneous Linear Equations, Applications of Second-Order Differential Equations, Using Series to Solve Differential Equations, Rotation of Axes, and (for instructors only) Hyperbolic Functions ■ Links, for each chapter, to outside Web resources ■ Archived Problems (drill exercises that appeared in previous editions, together with their solutions) ■ Challenge Problems (some from the Focus on Problem Solving sections of prior editions) Content Diagnostic Tests The book begins with four diagnostic tests, in Basic Algebra, Analytic Geometry, Functions, and Trigonometry. A Preview of Calculus This is an overview of the subject and includes a list of questions to motivate the study of calculus. 1 ■ Functions and Models From the beginning, multiple representations of functions are stressed: verbal, numerical, visual, and algebraic. A discussion of mathematical models leads to a review of the stan- PREFACE xvii dard functions, including exponential and logarithmic functions, from these four points of view. Parametric curves are introduced in the first chapter, partly so that curves can be drawn easily, with technology, whenever needed throughout the text. This early placement also enables tangents to parametric curves to be treated in Section 3.4 and graphing such curves to be covered in Section 4.4. 2 ■ Limits and Derivatives The material on limits is motivated by a prior discussion of the tangent and velocity problems. Limits are treated from descriptive, graphical, numerical, and algebraic points of view. (The precise definition of a limit is provided in Appendix D for those who wish to cover it.) It is important not to rush through Sections 2.6–2.8, which deal with derivatives (especially with functions defined graphically and numerically) before the differentiation rules are covered in Chapter 3. Here the examples and exercises explore the meanings of derivatives in various contexts. Section 2.8 foreshadows, in an intuitive way and without differentiation formulas, the material on shapes of curves that is studied in greater depth in Chapter 4. 3 ■ Differentiation Rules All the basic functions are differentiated here. When derivatives are computed in applied situations, students are asked to explain their meanings. Optional topics (hyperbolic functions, an early introduction to Taylor polynomials) are explored in Discovery and Laboratory Projects. (A full treatment of hyperbolic functions is available to instructors on the website.) 4 ■ Applications of Differentiation The basic facts concerning extreme values and shapes of curves are derived using the Mean Value Theorem as the starting point. Graphing with technology emphasizes the interaction between calculus and calculators and the analysis of families of curves. Some substantial optimization problems are provided, including an explanation of why you need to raise your head 42° to see the top of a rainbow. 5 ■ Integrals The area problem and the distance problem serve to motivate the definite integral. I have decided to make the definition of an integral easier to understand by using subintervals of equal width. Emphasis is placed on explaining the meanings of integrals in various contexts and on estimating their values from graphs and tables. There is no separate chapter on techniques of integration, but substitution and parts are covered here and other methods are treated briefly. Partial fractions are given full treatment in Appendix G. The use of computer algebra systems is discussed in Section 5.8. 6 ■ Applications of Integration General methods, not formulas, are emphasized. The goal is for students to be able to divide a quantity into small pieces, estimate with Riemann sums, and recognize the limit as an integral. There are more applications here than can realistically be covered in a given course. Instructors should select applications suitable for their students and for which they themselves have enthusiasm. Some instructors like to cover polar coordinates (Appendix H) here. Others prefer to defer this topic to when it is needed in third semester (with Section 9.7 or just before Section 12.4). 7 ■ Differential Equations Modeling is the theme that unifies this introductory treatment of differential equations. Direction fields and Euler’s method are studied before separable equations are solved explicitly, so that qualitative, numerical, and analytic approaches are given equal consideration. These methods are applied to the exponential, logistic, and other models for population growth. Predator-prey models are used to illustrate systems of differential equations. 8 ■ Infinite Sequences and Series Tests for the convergence of series are considered briefly, with intuitive rather than formal justifications. Numerical estimates of sums of series are based on which test was used to prove convergence. The emphasis is on Taylor series and polynomials and their applications to physics. Error estimates include those from graphing devices. xviii PREFACE 9 ■ Vectors and The Geometry of Space The dot product and cross product of vectors are given geometric definitions, motivated by work and torque, before the algebraic expressions are deduced. To facilitate the discussion of surfaces, functions of two variables and their graphs are introduced here. 10 ■ Vector Functions The calculus of vector functions is used to prove Kepler’s First Law of planetary motion, with the proofs of the other laws left as a project. In keeping with the introduction of parametric curves in Chapter 1, parametric surfaces are introduced as soon as possible, namely, in this chapter. I think an early familiarity with such surfaces is desirable, especially with the capability of computers to produce their graphs. Then tangent planes and areas of parametric surfaces can be discussed in Sections 11.4 and 12.6. 11 ■ Partial Derivatives Functions of two or more variables are studied from verbal, numerical, visual, and algebraic points of view. In particular, I introduce partial derivatives by looking at a specific column in a table of values of the heat index (perceived air temperature) as a function of the actual temperature and the relative humidity. Directional derivatives are estimated from contour maps of temperature, pressure, and snowfall. 12 ■ Multiple Integrals Contour maps and the Midpoint Rule are used to estimate the average snowfall and average temperature in given regions. Double and triple integrals are used to compute probabilities, areas of parametric surfaces, volumes of hyperspheres, and the volume of intersection of three cylinders. 13 ■ Vector Fields Vector fields are introduced through pictures of velocity fields showing San Francisco Bay wind patterns. The similarities among the Fundamental Theorem for line integrals, Green’s Theorem, Stokes’ Theorem, and the Divergence Theorem are emphasized. Ancillaries Calculus: Concepts and Contexts, Fourth Edition, is supported by a complete set of ancillaries developed under my direction. Each piece has been designed to enhance student understanding and to facilitate creative instruction. The table on pages xxi and xxii lists ancillaries available for instructors and students. Acknowledgments I am grateful to the following reviewers for sharing their knowledge and judgment with me. I have learned something from each of them. Fourth Edition Reviewers Jennifer Bailey, Colorado School of Mines Lewis Blake, Duke University James Cook, North Carolina State University Costel Ionita, Dixie State College Lawrence Levine, Stevens Institute of Technology Scott Mortensen, Dixie State College Drew Pasteur, North Carolina State University Jeffrey Powell, Samford University Barbara Tozzi, Brookdale Community College Kathryn Turner, Utah State University Cathy Zucco-Tevelof, Arcadia University Previous Edition Reviewers Irfan Altas, Charles Sturt University William Ardis, Collin County Community College Barbara Bath, Colorado School of Mines Neil Berger, University of Illinois at Chicago Jean H. Bevis, Georgia State University Martina Bode, Northwestern University Jay Bourland, Colorado State University Paul Wayne Britt, Louisiana State University Judith Broadwin, Jericho High School (retired) Charles Bu, Wellesley University Meghan Anne Burke, Kennesaw State University Robert Burton, Oregon State University PREFACE Roxanne M. Byrne, University of Colorado at Denver Maria E. Calzada, Loyola University–New Orleans Larry Cannon, Utah State University Deborah Troutman Cantrell, Chattanooga State Technical Community College Bem Cayco, San Jose State University John Chadam, University of Pittsburgh Robert A. Chaffer, Central Michigan University Dan Clegg, Palomar College Camille P. Cochrane, Shelton State Community College James Daly, University of Colorado Richard Davis, Edmonds Community College Susan Dean, DeAnza College Richard DiDio, LaSalle University Robert Dieffenbach, Miami University–Middletown Fred Dodd, University of South Alabama Helmut Doll, Bloomsburg University William Dunham, Muhlenberg College David A. Edwards, The University of Georgia John Ellison, Grove City College Joseph R. Fiedler, California State University–Bakersfield Barbara R. Fink, DeAnza College James P. Fink, Gettysburg College Joe W. Fisher, University of Cincinnati Robert Fontenot, Whitman College Richard L. Ford, California State University Chico Laurette Foster, Prairie View A & M University Ronald C. Freiwald, Washington University in St. Louis Frederick Gass, Miami University Gregory Goodhart, Columbus State Community College John Gosselin, University of Georgia Daniel Grayson, University of Illinois at Urbana–Champaign Raymond Greenwell, Hofstra University Gerrald Gustave Greivel, Colorado School of Mines John R. Griggs, North Carolina State University Barbara Bell Grover, Salt Lake Community College Murli Gupta, The George Washington University John William Hagood, Northern Arizona University Kathy Hann, California State University at Hayward Richard Hitt, University of South Alabama Judy Holdener, United States Air Force Academy Randall R. Holmes, Auburn University Barry D. Hughes, University of Melbourne Mike Hurley, Case Western Reserve University Gary Steven Itzkowitz, Rowan University xix Helmer Junghans, Montgomery College Victor Kaftal, University of Cincinnati Steve Kahn, Anne Arundel Community College Mohammad A. Kazemi, University of North Carolina, Charlotte Harvey Keynes, University of Minnesota Kandace Alyson Kling, Portland Community College Ronald Knill, Tulane University Stephen Kokoska, Bloomsburg University Kevin Kreider, University of Akron Doug Kuhlmann, Phillips Academy David E. Kullman, Miami University Carrie L. Kyser, Clackamas Community College Prem K. Kythe, University of New Orleans James Lang, Valencia Community College–East Campus Carl Leinbach, Gettysburg College William L. Lepowsky, Laney College Kathryn Lesh, University of Toledo Estela Llinas, University of Pittsburgh at Greensburg Beth Turner Long, Pellissippi State Technical Community College Miroslav Lovrić, McMaster University Lou Ann Mahaney, Tarrant County Junior College–Northeast John R. Martin, Tarrant County Junior College Andre Mathurin, Bellarmine College Prep R. J. McKellar, University of New Brunswick Jim McKinney, California State Polytechnic University–Pomona Richard Eugene Mercer, Wright State University David Minda, University of Cincinnati Rennie Mirollo, Boston College Laura J. Moore-Mueller, Green River Community College Scott L. Mortensen, Dixie State College Brian Mortimer, Carleton University Bill Moss, Clemson University Tejinder Singh Neelon, California State University San Marcos Phil Novinger, Florida State University Richard Nowakowski, Dalhousie University Stephen Ott, Lexington Community College Grace Orzech, Queen’s University Jeanette R. Palmiter, Portland State University Bill Paschke, University of Kansas David Patocka, Tulsa Community College–Southeast Campus Paul Patten, North Georgia College Leslie Peek, Mercer University xx PREFACE Mike Pepe, Seattle Central Community College Dan Pritikin, Miami University Fred Prydz, Shoreline Community College Denise Taunton Reid, Valdosta State University James Reynolds, Clarion University Hernan Rivera, Texas Lutheran University Richard Rochberg, Washington University Gil Rodriguez, Los Medanos College David C. Royster, University of North Carolina–Charlotte Daniel Russow, Arizona Western College Dusty Edward Sabo, Southern Oregon University Daniel S. Sage, Louisiana State University N. Paul Schembari, East Stroudsburg University Dr. John Schmeelk, Virginia Commonwealth University Bettina Schmidt, Auburn University at Montgomery Bernd S.W. Schroeder, Louisiana Tech University Jeffrey Scott Scroggs, North Carolina State University James F. Selgrade, North Carolina State University Brad Shelton, University of Oregon Don Small, United States Military Academy–West Point Linda E. Sundbye, The Metropolitan State College of Denver Richard B. Thompson,The University of Arizona William K. Tomhave, Concordia College Lorenzo Traldi, Lafayette College Alan Tucker, State University of New York at Stony Brook Tom Tucker, Colgate University George Van Zwalenberg, Calvin College Dennis Watson, Clark College Paul R. Wenston, The University of Georgia Ruth Williams, University of California–San Diego Clifton Wingard, Delta State University Jianzhong Wang, Sam Houston State University JingLing Wang, Lansing Community College Michael B. Ward, Western Oregon University Stanley Wayment, Southwest Texas State University Barak Weiss, Ben Gurion University–Be’er Sheva, Israel Teri E. Woodington, Colorado School of Mines James Wright, Keuka College In addition, I would like to thank Ari Brodsky, David Cusick, Alfonso Gracia-Saz, Emile LeBlanc, Tanya Leise, Joe May, Romaric Pujol, Norton Starr, Lou Talman, and Gail Wolkowicz for their advice and suggestions; Al Shenk and Dennis Zill for permission to use exercises from their calculus texts; COMAP for permission to use project material; Alfonso Gracia-Saz, B. Hovinen, Y. Kim, Anthony Lam, Romaric Pujol, Felix Recio, and Paul Sally for ideas for exercises; Dan Drucker for the roller derby project; and Tom Farmer, Fred Gass, John Ramsay, Larry Riddle, V. K. Srinivasan, and Philip Straffin for ideas for projects. I’m grateful to Dan Clegg, Jeff Cole, and Tim Flaherty for preparing the answer manuscript and suggesting ways to improve the exercises. As well, I thank those who have contributed to past editions: Ed Barbeau, George Bergman, David Bleecker, Fred Brauer, Andy Bulman-Fleming, Tom DiCiccio, Martin Erickson, Garret Etgen, Chris Fisher, Stuart Goldenberg, Arnold Good, John Hagood, Gene Hecht, Victor Kaftal, Harvey Keynes, E. L. Koh, Zdislav Kovarik, Kevin Kreider, Jamie Lawson, David Leep, Gerald Leibowitz, Larry Peterson, Lothar Redlin, Peter Rosenthal, Carl Riehm, Ira Rosenholtz, Doug Shaw, Dan Silver, Lowell Smylie, Larry Wallen, Saleem Watson, and Alan Weinstein. I also thank Stephanie Kuhns, Rebekah Million, Brian Betsill, and Kathi Townes of TECH-arts for their production services; Marv Riedesel and Mary Johnson for their careful proofing of the pages; Thomas Mayer for the cover image; and the following Brooks/ Cole staff: Cheryll Linthicum, editorial production project manager; Jennifer Jones, Angela Kim, and Mary Anne Payumo, marketing team; Peter Galuardi, media editor; Jay Campbell, senior developmental editor; Jeannine Lawless, associate editor; Elizabeth Neustaetter, editorial assistant; Bob Kauser, permissions editor; Becky Cross, print/media buyer; Vernon Boes, art director; Rob Hugel, creative director; and Irene Morris, cover designer. They have all done an outstanding job. I have been very fortunate to have worked with some of the best mathematics editors in the business over the past three decades: Ron Munro, Harry Campbell, Craig Barth, Jeremy Hayhurst, Gary Ostedt, Bob Pirtle, and now Richard Stratton. Special thanks go to all of them. JAMES STEWART Ancillaries for Instructors PowerLecture CD-ROM with JoinIn and ExamView ISBN 0-495-56049-9 Contains all art from the text in both jpeg and PowerPoint formats, key equations and tables from the text, complete pre-built PowerPoint lectures, and an electronic version of the Instructor’s Guide. Also contains JoinIn on TurningPoint personal response system questions and ExamView algorithmic test generation. See below for complete descriptions. TEC Tools for Enriching™ Calculus by James Stewart, Harvey Keynes, Dan Clegg, and developer Hu Hohn TEC provides a laboratory environment in which students can explore selected topics. TEC also includes homework hints for representative exercises. Available online at www.stewartcalculus.com. Instructor’s Guide by Douglas Shaw and James Stewart ISBN 0-495-56047-2 Each section of the main text is discussed from several viewpoints and contains suggested time to allot, points to stress, text discussion topics, core materials for lecture, workshop/ discussion suggestions, group work exercises in a form suitable for handout, and suggested homework problems. An electronic version is available on the PowerLecture CD-ROM. Instructor’s Guide for AP ® Calculus by Douglas Shaw ExamView Create, deliver, and customize tests and study guides (both print and online) in minutes with this easy-to-use assessment and tutorial software on CD. Includes full algorithmic generation of problems and complete questions from the Printed Test Bank. JoinIn on TurningPoint Enhance how your students interact with you, your lecture, and each other. Brooks/Cole, Cengage Learning is now pleased to offer you book-specific content for Response Systems tailored to Stewart’s Calculus, allowing you to transform your classroom and assess your students’ progress with instant in-class quizzes and polls. Contact your local Cengage representative to learn more about JoinIn on TurningPoint and our exclusive infrared and radio-frequency hardware solutions. Text-Specific DVDs ISBN 0-495-56050-2 Text-specific DVD set, available at no charge to adopters. Each disk features a 10- to 20-minute problem-solving lesson for each section of the chapter. Covers both single- and multivariable calculus. Solution Builder www.cengage.com/solutionbuilder The online Solution Builder lets instructors easily build and save personal solution sets either for printing or posting on password-protected class websites. Contact your local sales representative for more information on obtaining an account for this instructor-only resource. Ancillaries for Instructors and Students ISBN 0-495-56059-6 Taking the perspective of optimizing preparation for the AP exam, each section of the main text is discussed from several viewpoints and contains suggested time to allot, points to stress, daily quizzes, core materials for lecture, workshop/ discussion suggestions, group work exercises in a form suitable for handout, tips for the AP exam, and suggested homework problems. Complete Solutions Manual Single Variable by Jeffery A. Cole and Timothy J. Flaherty ISBN 0-495-56060-X ISBN 0-495-56121-5 Whether you prefer a basic downloadable eBook or a premium multimedia eBook with search, highlighting, and note taking capabilities as well as links to videos and simulations, this new edition offers a range of eBook options to fit how you want to read and interact with the content. Stewart Specialty Website www.stewartcalculus.com Contents: Algebra Review Additional Topics Drill Web Links History of exercises Challenge Problems Mathematics Tools for Enriching Calculus (TEC) N N Multivariable N N N N by Dan Clegg ISBN 0-495-56056-1 Includes worked-out solutions to all exercises in the text. Printed Test Bank by William Tomhave and Xuequi Zeng ISBN 0-495-56123-1 Contains multiple-choice and short-answer test items that key directly to the text. |||| Electronic items eBook Option |||| Printed items Enhanced WebAssign Instant feedback, grading precision, and ease of use are just three reasons why WebAssign is the most widely used homework system in higher education. WebAssign’s homework delivery system lets instructors deliver, collect, grade and record assignments via the web. And now, this proven system has been enhanced to include end-of-section problems from Stewart’s Calculus: Concepts and Contexts—incorporating exercises, (Table continues on page xxii.) xxi Another random document with no related content on Scribd: into the boilers, and accumulated there. It saponified and formed a foam which filled the whole boiler and caused the water to be worked over with the steam as fast as it could be fed in. I have always wondered why the engine, being vertical, should not have exhibited any sign of the water working through it at the upper end of the cylinder. The explanation after all appears simple. The water on entering the steam chest mostly fell to the bottom and little passed through the upper ports. The trouble from oil was not felt at all in the Lancashire boiler. This, I suppose, was due to three causes. The latter held a far greater body of water, had a much larger extent of evaporating surface, and far greater steam capacity. I was always sorry that I did not give the Harrison boiler the better chance it would have had with a jet condenser. In this pair of diagrams, which are copied from the catalogue of Ormerod, Grierson & Co., the low steam pressure, 29 pounds above the atmosphere, will be observed. This was about the pressure commonly carried. The pressure in the exhibition boilers, 75 pounds, was exhibited by Mr. John Hick, of Bolton, as a marked advance on the existing practice. In preparing for the governor manufacture I had my first revelation of the utter emptiness of the Whitworth Works. Iron gear patterns were required, duplicates of those which had been cut for me at home by Mr. Pratt. The blanks for these gears were turned as soon as possible after I reached Manchester, and sent to the Whitworth Works to be cut. It seemed as though we should never get them. Finally, after repeated urging, the patterns came. I was sent for to come into the shop and see them. They were in the hands of the best fitter we had, who, by the way, was a Swedenborgian preacher and preached every Sunday. The foreman told me he had given them to this man to see if it was possible to do anything with them, and he thought I ought to see them before he set about it. I could hardly believe my eyes. There was no truth about them. The spaces and the teeth differed so much that the same tooth would be too small for some spaces and could not be wedged into others; some would be too thick or too thin at one end. They were all alike bad, and presented all kinds of badness. It was finally concluded to make the best of them, and this careful man worked on them more than two days to make them passable. The first governor order that was booked was the only case that ever beat me. I went to see the engine. It was a condensing beamengine of good size, made by Ormerod, Grierson & Co. to maintain the vacuum in a tube connecting two telegraph offices in Manchester, and had been built to the plans and specifications of the telegraph company’s engineer. The engine had literally nothing to do. A little steam air-pump that two men could have lifted and set on a bench would have been just suitable for the work. They could not carry low enough pressure nor run slowly enough. On inspection I reported that we should have nothing to do with it. The custom of making whatever customers order and taking no responsibility was first illustrated to me in this curious way. I saw a queer-looking boiler being finished in the boiler-shop. In reply to my question the foreman told me they were making it for a cottonspinner, according to a plan of his own. It consisted of two boilers, one within the other. The owner’s purpose was to carry the ordinary steam pressure in the outer boiler, and a pressure twice as great in the inner one, when the inner boiler would have to suffer the stress of only one half the pressure it was carrying. I asked the superintendent afterwards why they did not tell that man that he could not maintain steam at two different temperatures on the opposite sides of the same sheets. He replied: “Because we do not find it profitable to quarrel with our customers. That is his idea. If we had told him there was nothing in it, he would not have believed us, but would have got his boiler made somewhere else.” Perhaps the most curious experience I ever had was that of getting the governor into cotton-mills. There was a vast field all around us, and we looked for plenty of orders. This was the reception I met with every time. After listening to the winning story I had to tell, the cotton lord would wind up with this question: “Well, sir, have you got a governor in a large cotton-mill?” After my answer in the negative I was bowed out. I early got an order from Titus Salt & Son, of Saltaire, for two large governors but these did not weigh at all with a cotton-spinner; they made alpaca goods. The way the governor was finally got into cotton-mills, where afterwards its use became general, was the most curious part. A mill in the city of Manchester was troubled by having its governor fly in pieces once in a while. After one of these experiences the owners thought that they might cure the difficulty by getting one of my governors. That flew in pieces in a week. I went to see the engine. The cause of all the trouble appeared at a glance. The fly-wheel was on the second-motion shaft which ran at twice the speed of the main shaft, and the gearing between them was roaring away enough to deafen one. The governor was driven by gearing. The vibrations transmitted to the governor soon tired the arms out. I saw the son of the principal owner, and explained the cause of the failure of every governor they had tried, and told him the only remedy, which would be a complete one, would be to drive the governor by a belt. That, he replied, was not to be thought of for an instant. I told him he knew himself that a governor could not endure if driven in any other way, and that I had hundreds of governors driven by belts, which were entirely reliable in all cases. “But,” said he, “supposing the belt runs off the pulley.” “The consequence,” I replied, “cannot be worse than when the governor flies in pieces.” After wasting considerable time in talk, he said, “Well, leave it till my father comes home; he is absent for a few days.” “No,” said I, “if I can’t convince a young man, I shall not try to convince an old man.” Finally, with every possible stipulation to make it impossible for the belt to come off, he yielded his assent, and I had the governor on in short order, lacing the belt myself, to make sure that it was butt-jointed and laced in the American fashion. More than three years afterwards, two days before I was to sail for home, I met this man on High Street, in Manchester. It was during the Whitsuntide holidays, and the street was almost deserted. He came up to me, holding out both hands and grasping mine most cordially. “Do you know,” said he, “that we have increased our product 10 per cent., and don’t have half as many broken threads as we had before, and it’s all that belt.” Condenser and Air-pump designed by Mr. Porter. (Cross-section) The tendency towards the horizontal type of engine, in place of the beam-engine, began to be quite marked in England about that time. This was favorable to the use of the Allen engine. The only thing that seemed wanting to its success was a directly connected jet condenser. No one believed that an air-pump could be made to run successfully at the speed of 150 double strokes per minute. Yet this had to be done, or I could not look for any considerable adoption of the high-speed engine. This subject occupied my mind continually. When I returned from Oporto, I had thought out the plan of this condenser, and at once set about the drawings for it. No alteration was ever made from the first design of the condenser, which I intended to show with the engine at the coming Paris Exposition in 1867, and which I finally did succeed in showing there, but under very different and unexpected relations. The philosophy of this condenser is sufficiently shown in the accompanying vertical cross-section. A hollow ram, only equal in weight to the water which it displaced, ran through a stuffing-box at the front end of the chamber, and was connected with an extension of the piston-rod of the engine. So the center line of the engine extended through this single-acting ram, which had the full motion of the piston. It ran through the middle of a body of water, the surface of which fell as the ram was withdrawn, and rose as it returned. A quiet movement of the water was assured by three means: First, the motion of the ram was controlled by the crank of the engine, and so began and ceased insensibly. Second, the motion of the ram, of two feet, produced a rise or fall of the surface of the water of only about one inch. Third, the end of the ram was pointed, a construction which does not appear in this sectional view, permitting it to enter and leave the water at every point gradually. Both the condenser and the hot-well were located above the chamber in which the ram worked. The problem was to obtain complete displacement by means of solid water without any admixture of free air, the expansion of which as the plunger was withdrawn would reduce the efficiency of the airpump. To effect this object the air must be prevented from mingling with the water, and must be delivered into the hot-well first. This was accomplished by two means: First, placing the condenser as well as the hot-well above the air-pump chamber, as already stated, and secondly, inclining the bottom of the condenser, so that the water would pass through the inlet valves at the side farthest from, and the air at the side nearest to, the hot-well. Thus the air remained above the water, and as the latter rose it sent the air before it quite to the delivery valves. Pains were taken to avoid any place where air could be trapped, so it was certain that on every stroke the air would be sent through the delivery valves first, mingled air and water, if there were any, next, and the solid water last, insuring perfect displacement. I have a friend who has often asked me, with a manner showing his conviction that the question could not be answered, “How can you know that anything will work until you have tried it?” In this case I did know that this condenser would work at rapid speed before I tried it. The event proved it, and any engineer could have seen that it must have worked. The only question in my mind was as to the necessity of the springs behind the delivery valves. Experiment was needed to settle that question, which it did in short order. At the speed at which the engine ran, the light springs improved the vacuum a full pound, showing that without them these valves did not close promptly. The following important detail must not be overlooked. The rubber disk valves were backed by cast-iron plates, which effectually preserved them from being cut or even marked by the brass gratings. These plates were made with tubes standing in the middle of them, as shown. These tubes afforded long guides on the stems, and a projection of them on the under side held the valves in place without any wear. They also determined the rise of the valves. The chambers, being long and narrow, accommodated three inlet and three outlet valves. The jet of water struck the opposite wall with sufficient force to fill the chamber with spray. When the plans for this condenser were completed, and the Evan Leigh engine had been vindicated, I felt that the success of the highspeed system was assured, and looked forward to a rapidly growing demand for the engines. We got out an illustrated catalogue of sizes, in which I would have put the condenser, but the firm decided that it would be better to wait for that until it should be on the same footing with the engine, as an accomplished fact. Suddenly, like thunder from a clear sky, I received notice that Ormerod, Grierson & Co. were in difficulties, had stopped payment, placed their books in the hands of a firm of accountants, and called a meeting of their creditors, and the works were closed. Some of their enormous contracts had proved losing ones. I had made such provision in my contract with them that on their failure my license to them became void. Otherwise it would have been classed among their assets. CHAPTER XII Introduction to the Whitworth Works. Sketch of Mr. Whitworth. Experience in the Whitworth Works. Our Agreement which was never Executed. First Engine in England Transmitting Power by a Belt. was still debating with myself what course to take, when I received a note from Mr. W. J. Hoyle, secretary of the Whitworth Company, inquiring if I were free from any entanglement with the affairs of Ormerod, Grierson & Co., to which I was able to make a satisfactory reply. Mr. Hoyle was then a stranger to me. It appeared that he was an accomplished steam engineer, and had been employed as an expert to test one of my engines in operation, an engine which we had made for a mill-owner in Bradford. He had been very favorably impressed by the engine, so much so as to form this scheme. He had been with the Whitworth Company only a short time, and was struck with the small amount of work they were doing in their tool department; and after his observation of the engine at Bradford, learning of the stoppage of Ormerod, Grierson & Co., it occurred to him that it would be a good thing for his company to undertake the manufacture of these engines. After receiving my answer to his preliminary inquiry, having Mr. Whitworth, as he afterwards told me, where he could not get away, on a trip from London to Manchester, he laid the plan before him and talked him into it. I directly after received an invitation to meet Mr. Whitworth at his office, and here commenced what I verily believed was one of the most remarkable experiences that any man ever had. William J. Hoyle In the course of our pretty long interview, which terminated with the conclusion of a verbal agreement, Mr. Whitworth talked with me quite freely, and told me several things that surprised me. One was the frank statement that he divided all other toolmakers in the world into two classes, one class who copied him without giving him any credit, and the other class who had the presumption to imagine that they could improve on him. His feelings towards both these classes evidently did not tend to make him happy. Another thing, which I heard without any sign of my amazement, was that he had long entertained the purpose of giving to the world the perfect steamengine. “That is,” he explained, “an engine embodying all those essential principles to which steam-engine builders must sooner or later come.” This, he stated, had been necessarily postponed while he was engaged in developing his system of artillery, but he was nearing the completion of that work and should then be able to devote himself to it. I cannot perhaps do better than stop here and give my impressions of Mr. Whitworth. He was in all respects a phenomenal man. As an engineer, or rather a toolmaker, he addressed himself to all fundamental constructive requirements and problems, and comprehended everything in his range and grasp of thought, continually seeking new fields to conquer. Long after the period here referred to he closed his long and wonderful career by giving to the world the hollow engine shaft and the system of hydraulic forging. At that time he was confidently anticipating the adoption by all nations of his system of artillery. He had made an immense advance, from spherical shot, incapable of accurate aim and having a high trajectory, to elongated shot, swiftly rotating in its flight and having a comparatively flat trajectory, and which could hit the mark and penetrate with destructive effect at distances of several miles. These fundamental features of modern artillery thus originated with Mr. Whitworth. All his other features have been superseded, but his elongated pointed rotating projectile will remain until nations shall learn war no more; a time which in the gradual development of humanity cannot be far away. Before I left England, however, he had abandoned his artillery plans in most bitter disappointment. He had met the English official mind. By the authorities of the war and navy departments it had been unanimously decided that what England wanted was, not accuracy of aim and penetration at long range, but smashing effects at close quarters. The record of that is to be found in the proceedings of the House of Commons in 1868, only thirtynine years ago. Think of that! Mr. Whitworth was not only the most original engineering genius that ever lived. He was also a monumental egotist. His fundamental idea was always prominent, that he had taught the world not only all that it knew mechanically, but all it ever could know. His fury against tool-builders who improved on his plans was most ludicrous. He drew no distinction between principles and details. He must not be departed from even in a single line. No one in his works dared to think. This disposition had a striking illustration only a short time— less than a year—before I went there. He had no children. His nearest relatives were two nephews, W. W. and J. E. Hulse. The latter was a tool-manufacturer in Salford. W. W. Hulse was Mr. Whitworth’s superintendent, and had been associated with him for twenty-four years, for a long time as his partner, the firm being Joseph Whitworth & Company. Lately the business had been taken over by a corporation formed under the style of the Whitworth Company, and Mr. Hulse became the general superintendent. Mr. Whitworth was taken sick, and for a while was not expected to live, and no one thought, even if he did get better, that he would ever be able to visit his works again. Mr. Hulse had been chafing under his restraint, and during Mr. Whitworth’s absence proceeded to make a few obvious improvements in their tools, such, for example, as supporting the table of their shaper, so that it would not yield under the cut. To the surprise of every one, Mr. Whitworth got well, and after more than six months’ absence, he appeared again at the works. Walking through, he noted the changes that had been made, sent for Mr. Hulse, discharged him on the spot, and ordered everything restored to its original form. To return now to my own experience. Since Mr. Whitworth had been absorbed in his artillery development he had given only a cursory oversight to the tool manufacture. Mr. Hulse had been succeeded as superintendent by a man named Widdowson, whose only qualification for his position was entire subserviency to Mr. Whitworth. Sir Joseph Whitworth My drawings and patterns were purchased by the Whitworth Company, and I was installed with one draftsman in a separate office, and prepared to put the work in hand at once for a 12×24-inch engine for the Paris Exposition, where Ormerod, Grierson & Co. had secured the space, and the drawings for which I had completed. If I remember rightly, the patterns were finished also. While I was getting things in order, Mr. Widdowson came into my office, and in a very important manner said to me: “You must understand, sir, that we work here to the decimal system and all drawings must be conformed to it.” I received this order meekly, and we went to work to make our drawings all over, for the single purpose of changing their dimensions from binary to decimal divisions of the inch. There was of course quite a body of detail drawings, and to make these over, with the pains required to make these changes to an unaccustomed system, and make and mount the tracings, took us nearly three weeks. When finished I took the roll of tracings to Mr. Widdowson’s office. He was not in, and I left them for him. An hour or so later he came puffing and blowing into my office with the drawings. He was a heavy man, and climbing upstairs exhausted him. When he got his breath, he broke out: “We can’t do anything with these. Haven’t got a decimal gauge in the shop.” “You gave me express orders to make my drawings to the decimal system.” “Damn it, I meant in halves and quarters and all that, and write them decimals.” So all that work and time were thrown away, and we had to make a new set of tracings from the drawings I had brought, in order to figure the dimensions in decimals. He told me afterwards that when Mr. Whitworth commenced the manufacture of cylindrical gauges he made them to the decimal divisions of the inch, imagining that was a better mode of division than that by continual bisection, and supposing that he had influence enough to effect the change. But nobody would buy his gauges. He had to call them in and make what people wanted. “And now,” said Mr. Widdowson, “there is not a decimal gauge in the world.” He knew, too, for up to that time they made them all. So Mr. Whitworth could make a mistake, and I found that this was not the worst one that he had made. While time was being wasted in this manner, the subject of manufacturing the governors came up. Mr. Whitworth concluded that he would first try one on his own shop engine, so one was bought from Ormerod, Grierson & Co. I had a message from Mr. Widdowson to come to the shop and see my governor. It was acting in a manner that I had seen before, the counterpoise rising and dropping to its seat twice every time the belt lap came around. “Total failure, you see,” said Mr. Widdowson, “and I got a new belt for it, too.” I saw a chance to make an interesting observation, and asked him if he would get an old belt and try that. This he did, lapping the ends as before about 18 inches, according to the universal English custom, which I had long before found it necessary carefully to avoid. As I knew would be the case, the action was not improved at all. I then cut off the lap, butted the ends of the belt, and laced them in the American style, and lo! the trouble vanished. The governor stood motionless, only floating up and down slightly with the more important changes of load. Mr. Whitworth was greatly pleased, and at once set about their manufacture, in a full line of sizes. He made the change, to which I have referred already, from the urn shape to the semi-spherical form of the counterpoise. In this connection he laid the law down to me in this dogmatic fashion: “Let no man show me a mechanical form for which he cannot give me a mechanical reason.” But Jove sometimes nods. They were to exhibit in Paris a large slotting-machine. The form of the upright did not suit Mr. Whitworth exactly. He had the pattern set up in the erectingshop, and a board tacked on the side, cut to an outline that he directed. He came to look at it every day for a week, and ordered some change or other. Finally it was gotten to his mind, the pattern was altered accordingly, and a new casting made. This was set up in the shop, and I happened to be present when he came to see it. “Looks like a horse that has been taught to hold his head up,” said he. “Mechanical reason,” thought I, fresh from my lesson. When finished the slotting-machine was tried in the shop, and found to yield in the back. The tool sprang away from its work and rounded the corner. Mr. Whitworth had whittled the pattern away and ruined it. Instead of being sent to Paris, it was broken up. My experiment with the governor proved the defect in the English system of lacing belts. Every machine in the land, of whatever kind, tool or loom or spinning or drawing frame, or whatever it was, driven by a belt, halted in its motion every time the lap in the belt passed over a pulley, sufficiently to drop my governor, when the same motion was given to it, and no one had ever observed this irregularity. I thought they would never be ready to set about work on the engine. First, Mr. Widdowson ordered that every casting and forging, large and small, must be in the shop before one of them was put in hand. After this was done I found a number of men at work making sheet-iron templets of everything. I saw one man filing the threads in the edges of a templet for a ³⁄₈-inch bolt. When these were all finished and stamped, an operation that took quite a week, a great fuss was made about commencing work on everything simultaneously. I went into the shop to see what was going on. The first thing to attract my attention was the steam-chest, then made separate from the cylinder. A workman—their best fitter, as I afterwards learned— was engaged in planing out the cavities in which the exhaust valves worked. I saw no center line, and asked him where it was. He had never heard of such a thing. “What do you measure from?” “From the side of the casting.” I called his attention to the center line on the drawing, from which all the measurements were taken, and told him all about it. He seemed very intelligent, and under my direction set the chest up on a plane table and made a center line around it and another across it, and set out everything from these lines, and I left him going on finely. An hour later I looked in again. He was about his job in the old way. To my question he explained that his foreman had come around and told him I had no business in the shop, that he gave him his directions, and he must finish his job just as he began it. I made no reply but went to Mr. Hoyle’s office, and asked him if he knew what they were doing in the shop. He smiled and said, “I suppose they are finally making an engine for you.” “No, they are not.” “What are they doing?” “Making scrap iron.” “What do you mean?” I told him the situation. He took his hat and went out, saying, “I must see this myself.” A couple of hours later he sent for me, and told me this. “I have been all around the works and seen all that is doing. It is all of the same piece. I have had a long interview with Mr. Widdowson, and am sorry to tell you that we can’t make your engine; we don’t know how. It seems to be entirely out of our line. The intelligence does not exist in these works to make a steam-engine. Nobody knows how to set about anything. I have stopped the work, and want to know what you think had better be done about it?” I asked him to let me think the matter over till the next morning. I then went to him and suggested to him to let me find a skilled locomotive-erecter who was also a trained draftsman, and to organize a separate department for the engine and governor manufacture, and put this man at the head of it, to direct it without interference. This was gladly agreed to. I found a young man, Mr. John Watts, who proved to be the very man for the place. In a week we were running under Mr. Watts’ direction, and the engine was saved. But what a time the poor man had! Everything seemed to be done wrong. It is hardly to be believed. He could not get a rod turned round, or a hole bored round. In their toolmaking they relied entirely on grinding with “Turkey dust.” I once saw a gang of a dozen laborers working a long grinding-bar, in the bore, 10 inches diameter by 8 feet long, in the tailstock of an enormous lathe. I peered through this hole when the bar was withdrawn. It looked like a ploughed field. Scattered over it here and there were projections which had been ground off by these laborers. On the other hand, the planing done in these works was magnificent. I never saw anything to equal it. But circular work beat them entirely. I found that the lathe hands never thought of such a thing as getting any truth by the sliding cut. After that they went for the surface with coarse files, and relied for such approximate truth as they did get upon grinding with the everlasting Turkey dust. Mr. Whitworth invented the duplex lathe tool, but I observed that they never used it. I asked Mr. Widdowson why this was. “Because,” said he, “the duplex tool will not turn round.” After a while I found out why. When our engine was finished, Mr. Widdowson set it upon two lathe beds and ran it. Lucky that he did. The bottom of the engine bed was planed, and it could be leveled nicely on the flat surfaces of their lathe beds. The fly-wheel ran nearly a quarter of an inch out of truth. He set up some tool-boxes on one of the lathe beds, and turned the rim off in place, both sides and face being out. That, of course, made it run perfectly true. I asked the lathe hand how he could turn out such a job. He replied, “Come and see my lathe.” I found the spindle quite an eighth of an inch loose in the main bearing, the wear of twenty or thirty years. He told me all of the lathes in the works were in a similar condition. That explained many things. The mystery of those gear patterns was solved. Every spindle in the gear-cutting machine was wabbling loose in its holes. I can’t call them bearings. Now it appeared why they could not use the duplex tools. With a tool cutting on one side, they relied on the pressure of the cut to keep the lathe spindle in contact with the opposite side of its main bearing, and a poor reliance that was, but with a tool cutting on each side, fancy the situation. Then boring a true hole was obviously impossible. The workmen became indifferent; they had no reamers, relied entirely on grinding. I asked, Why do you not renew these worn-out bushings? but could never get an answer to the question. Some power evidently forbade it, and the fact is that no man about the place dared to think of such a thing as intimating to Mr. Whitworth that one of his lathe bearings required any fixing up, or that it was or could be anything short of perfect. He (Mr. Whitworth) had designed it as a perfect thing; ergo, it was perfect, and no man dared say otherwise. Our engine work was finally, as a last resort, done by Mr. Watts on new lathes, made for customers and used for a month or two before they were sent out. Not only in England, but on the Continent and in America, the Whitworth Works were regarded as the perfect machine-shop. I remember a visit I had at the Paris Exposition from Mr. Elwell, of the firm of Varrell, Elwell & Poulot, proprietors of the largest mechanical establishment in Paris. After expressing his unbounded admiration of the running of the engine, he said, “I warrant your fly-wheel runs true.” After observing it critically, he exclaimed, “Ah, they do those things at Whitworth’s!” The fact was Mr. Whitworth had cursed the British nation with the solid conical lathe-spindle bearing, a perfect bearing for ordinary- sized lathes and a most captivating thing—when new. These hardened steel cones, in hardened steel seats, ran in the most charming manner. But they wore more loose in the main bearing every day they ran, and there were no means for taking up the wear. It came on insensibly, and no one paid any attention to it. The cream of the joke was that people were so fascinated with this bearing that at that time no other could be sold in England, except for very large lathes. All toolmakers had to make it. I remember afterwards that Mr. Freeland, our best American toolmaker, who, as I have already mentioned, went to England and worked for some years as a journeyman in the Whitworth Works for the purpose of learning everything there that he could, did not bring back to America the conical bearing. The firm of Smith & Coventry were the first to fit their lathes with the means for taking up this wear, which took place only in the main bearing, where both the force of the cut and the weight of the piece were received. They made the conical seat for the back end of the spindle adjustable in the headstock and secured it by a thin nut on each end. This then could be moved backward sufficiently to let the forward cone up to its seat. This made it possible to use the solid bearing, but it involved this error, that after this adjustment the axis of the spindle did not coincide with the line connecting the lathe centers; but the two lines formed an angle with each other, which grew more decided every time the wear was taken up. This, however, was infinitely better than not to take up the wear at all. At that time the Whitworth Works were divided into four departments. These were screwing machinery, gauges, guns and machine tools. The first three of these were locked. I never entered either of them. The latter also, like most works in England, was closed to outsiders. No customer could see his work in progress. This department was without a head or a drawing-office. It seemed to be running it on its traditions. I once said to Mr. Hoyle, “There must at some time have been here mechanical intelligence of the highest order, but where is it?” They had occasionally an order for something out of their ancient styles, and their attempts to fill such orders were always ruinous. The following is a fair illustration. They had an order for a radial drill to be back-geared and strong enough to bore an 8-inch hole. Mr. Widdowson had the pattern for the upright fitted with the necessary brackets, and thought it was such a good thing that he would make two. The first one finished was tried in the shop, and all the gears in the arm were stripped. He woke up to the fact that he had forgotten to strengthen the transmitting parts, and moreover that the construction would not admit anything stronger. There was nothing to be done but to decline the order, chip off the brackets, and make these into single-speed drills. This I saw being done. Mr. Widdowson told me the following amusing story. The London Times had heard of the wonderful performance of Mr. Hoe’s multiplecylinder press, and concluded to have one of them of the largest size, ten cylinders. But, of course, Mr. Hoe did not know how to make his own presses. His work would do well enough for ignorant Americans, but not for an English Journal. The press must be made in England in the world-renowned Whitworth Works. Mr. Hoe sent over one of his experts to give them the information they might need, but they would not let him in the shop. Mr. Hulse told him they had the drawings and specifications and that was all they needed. When the press was finished they set it up in the shop and attempted to run it. The instant it started every tape ran off its pulleys, and an investigation showed that not a spindle or shaft was parallel with any other. They had no idea of the method that must be employed to ensure this universal alignment. After enormous labor they got these so that they were encouraged to make another trial, when after a few revolutions every spindle stuck fast in its bearings. Mr. Whitworth, absorbed in his artillery and spending most of his time in London, of course had no knowledge of how things were going on in his shop, of the utter want of ordinary intelligence. I formed a scheme for an application of Mr. Whitworth’s system of end measurement to the production of an ideally perfect dividingwheel. In this system Mr. Whitworth employed what he termed “the gravity piece.” This was a small steel plate about ¹⁄₈ of an inch in thickness, the opposite sides of which were parallel and had the most perfectly true and smooth surfaces that could be produced by scraping. The ends of the piece to be tested were perfectly squared, by a method which I will not stop here to describe, and were finished