9. Do labor-saving inventions help or harm workmen? Explain why the iron-puddlers were delighted when Kelly's first experiment in Johnstown failed. Was it for the same reason that the farm laborers looked upon McCormick's reaper with hostile eyes? Is the attitude of the workers in such cases natural? Is it justifiable? Give other examples of hostility to new inventions.

10. Make a list of six or eight questions which need to be answered in order to understand fully the poem, "The Conquest of the Air." 11. Explain the chief change which would take place in cities if it were impossible to build skyscrapers. What problems would be increased by such a change? What ones would be lessened?

12. Explain why skyscrapers would be impossible without elevators. 13. What is the most difficult problem of the builder of a skyscraper? 14. Why are skyscrapers prohibited in Paris? Is the height of buildings. limited in your community? Should it be limited? Give reasons. 15. Read again "The Thinker,” p. 153. Explain how the main idea of the poem is illustrated by each of the selections under discussion.

16. Write sentences in which you state the chief contribution to human welfare made by each of these inventions: reaper, steel converter, airplane, skyscraper.

17. Talks by volunteers: Tell about the most interesting skyscraper you have ever seen: the appearance of the building, its size, height, use, and the number of people it accommodates. If possible, illustrate your talk with pictures of both the exterior and the interior. Perhaps you can bring for comparison pictures (postals or magazine cuts) of other large skyscrapers.

18. Volunteer project: Which invention brought the inventor the largest fortune? (To answer this question you will need to look up the inventors or the inventions in the encyclopedia or in some of the references given on p. 134.)

Figures of Speech

A poet usually uses figures of speech — likenesses, comparisons, pictures to explain his thought. In the first stanza of "The Conquest of the Air," for example, Pulsifer compares the engine in an airplane to a "heart," the sound of the motor to "thunder," and the aviator to a "worm" which has just come from its chrysalis with "new wings" and has thus become "king of kings." One mark of a good poem is the beauty and appropriateness of the figures of speech it contains. Tell whether the figures of speech in the first stanza are beautiful and fitting. Read the poem again and make a list of the figures of speech which you like.

Judging the Value of Inventions

Two pupils collect the votes of the class on the relative value to man of the four inventions (p. 155) and score the results as follows:

1. For a first place...

2. For a second place

5 points -3 points I point

3. For a third place.

Report the result and ask the pupils who disagreed with the class decision on first place to explain their choice for first place.

ADDITIONAL READINGS. 1. "Industry's Greatest Asset Steel," W. J. Showalter, in National Geographic Magazine, 32:121–156. 2.“Foundations of Lofty Buildings," W. Skinner, in Century Magazine, 55: 771781. 3. "Wright Brothers," M. H. Wade, Light Bringers, 112–141. 4. "Manhattan," Walt Whitman. 5. "The Wright Brothers' Aeroplane," O. Wright and W. Wright, in C. L. Barstow's Progress of a United People, 125-134. 6. "When Reapers Were New," A. H. Sanford, Story of Agriculture in the United States, 144–158. 7. “Airships and Flying Machines," A. Williams, How It Works, 456-474. 8. "The Conquest of the Air," H. Thompson, Age of Invention, 220-245. 9. “Making the World's Agricultural Machinery," B. J. Hendrick, Age of Big Business, 149-169.

CLASS-LIBRARY READINGS

INVENTIONS OF MODERN MEN

1. "The Story of the Heavy-Gun Pointer," G. Flint, in Vocational Reader, 157-161.

2. "Eli Whitney, Inventor of the Cotton Gin," Makers of Our History, 123-134.

3. "Cyrus Hall McCormick, Inventor of the Reaper," ibid., 254-265. 4. "The Story in the Talking Machine," Wonder Book of Knowledge,

43-49.

5. "The Story in Elevators and Escalators," ibid., 232–241.

6. "The Reaper," Stories of Useful Inventions, 85–96.

7. "The Most Ingenious of Americans," Compton's Pictured Encyclopedia, 3 1083-1084.

8. "The Machines that Lift You Upstairs," ibid., 3: 1132–1134.

9. "Harnessing Explosions- the Story of the Gas Engine," ibid.,

4:1403-1406.

IO. How Cyrus McCormick Rode to Fame on a Reaper," ibid., 5:2095. II. "Six Principles that Rule All Machines," ibid., 5: 2187–2190.

12. "How the Phonograph Was Taught to Talk," ibid., 7: 2774-2776.

13. "Tools, the Builders of Civilization,” ibid., 8:3514-3516.

14. "The Story of Architecture," World Book, 1:322-329.

This selection describes the way a watch runs and how it is made. As you read, select the important details and try to keep them in mind.

If an electric automobile could be charged in fifteen seconds and then would run for forty hours without recharging, it would be looked upon as a great wonder; but to wind a watch in fifteen seconds and have it run for forty hours is so common that we forget what a wonder it is. When you wind your watch, you put some of the strength of your own right hand into it, and that is what makes it go. Every turn of the key or the stem winds up tighter and tighter a spring from one to two feet long, but so slender that it would take thousands to weigh a pound. This is the main spring. It is coiled up in a cup-shaped piece of metal called a "barrel"; so your own energy is literally barreled up in your watch.

This spring has three things to do. It must send the "short hand," or hour hand, around the dial or face of the watch once in twelve hours; it must send the "long hand," or minute hand, around once an hour; and it must also send the little "second hand" around its own tiny circle once a minute. To do this work requires four wheels. The first, or main, wheel is connected with the winding arrangements, and sets in motion the second, or

center, wheel, so called because it is usually in the center of the watch. This center wheel revolves once an hour and turns the minute hand. By skillful arrangement of cogs it also moves the hour hand around the dial once in twelve hours. The center wheel moves the third wheel. The chief business of the third wheel is to make the fourth turn in the same direction as the center wheel. The fourth wheel revolves once a minute, and with it turns the tiny second hand.

Suppose that a watch has been made with only the main spring, the four wheels, and the three hands, what would happen when it was wound? You can tell very easily by winding up a mechanical mouse or a train of cars or any other toy that goes by a spring. The toy will go fast at first, then more and more slowly, then it will stop. This sort of motion might do for a mouse, but it would not answer for a watch. A watch must move with steadiness and regularity. To bring this about, there is a fifth wheel. Its fifteen teeth are shaped like hooks, and it has seven accompaniments, the balance wheel, the hair spring, and five others. This wheel, together with its accompaniments, is able to stop the motion of the watch five times a second and start it again so quickly that we do not realize its having been stopped at all. A tiny arm holds the wheel firmly, and then lets it escape. Therefore, the fifth wheel and its accompaniments are called the "escapement." This catching and letting go is what makes the ticking.

A watch made in this way would run very well until a hot or a cold day came; then there would be trouble. Heat makes metals expand and makes springs less elastic. Therefore on a hot day the watch would go more slowly and so lose time; while on a cold day it would go too fast and would gain time. This fault is corrected by the balance, a wheel whose rim is not one circle, but two halfcircles, so cunningly made that the hotter this rim grows, the smaller its diameter becomes.

All this would be difficult enough to manage if a watch was as large as a cartwheel, with wheels a foot in diameter; but it is a marvel how so many kinds of wheels and screws and springs, one hundred and fifty in all, can be put into a case sometimes not more than an inch in diameter, and can find room to work. It is

quite as much of a marvel how they can be manufactured and handled.

Remembering how accurate every piece must be, it is no wonder that in Switzerland, where all this work used to be done by hand, a boy had to go to a "watch school" for fourteen years before he was considered able to make a really fine watch. He began at the beginning and was taught to make, first, wooden handles for his tools, then the tools themselves, such as files and screw drivers. His next work was to make wooden watchcases as large as dinner-plates. After this, he was given the frame to which the various wheels of a watch are fastened and was taught how and where to drill the holes for wheels and screws. After lessons in making the finer tools to be used, he was allowed to make a watch frame. All this took several years, for he had to do the same work over and over until his teachers were satisfied with it.

Then he was promoted to the second room. Here he learned to adjust the stem-winding parts, to do fine cutting and filing, and to make watches that would strike the hour and even the minute. Room three was called the "train room," because the wheels of a watch are spoken of as "the train." The model watch in this room was as large as a saucer. The young man had to study every detail of this watch, and also to learn the use of a delicate little machine doing such fine work that it could cut twenty-four hundred tiny cogs on one of the little wheels of a watch. In the fourth room he learned to make the escapement wheel and some other parts; and he had to make them, not merely passably, but excellently.

In the fifth and last room, he was required to do the careful, patient work that makes a watch go perfectly. Special curves must be given to the hair spring, and the screws on the balance wheel must be carefully adjusted. If the watch ran faster when it was lying down than when it was hanging up, he learned that certain bearings were too coarse and must be made finer. In short, he must be able to make a watch that, whether hanging up or lying down, whether the weather was hot or cold, would not vary from correct time more than two and a half seconds a day at the most. Then, and not till then, was the student regarded as a firstclass watchmaker.