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FRANK M. MCMURRY, PH.D.
TEACHERS COLLEGE, COLUMBIA UNIVERSITY
C. BEVERLEY BENSON, C.E.
THE MACMILLAN COMPANY
All rights reserved
TO THE BOYS AND GIRLS WHO USE THIS BOOK:
Many of the most interesting questions that boys and girls ask are about how much and how many. They want to know how many pounds they weigh; how tall they are; how many miles an hour an airplane can travel; how much a pair of skates costs; how deep the ocean is; and how big coal mines are.
The questions in this book are of that kind. For instance, most of our bread is now made in large bakeries, and some of the questions are: How big is an oven that bakes 5000 loaves in an hour? How many barrels of flour does such a factory use in a day and in a year? How many acres of farm land does it take to raise enough wheat for such a factory? How many men are employed in it, and how many women would it take to make the same amount of bread at home? How much more or less expensive is baker's bread than homemade bread? And when you pay 6 cents for a loaf, how much of the money goes to the farmer; how much to the railroad, to the miller, and to the grocer?
The answers to these questions are worth knowing, but you must find them yourself, by figuring, just as the men who are interested in bread making have found them. And enough facts are always given for you to do that. You may often be surprised at the answers; and there will be so many about bread that they will tell you a long story. That is the reason Chapter Two in this book is called "The Story of Bread."
Chapter Six is "The Story of Coal." In this chapter you will learn the size of a certain mine in Illinois, which you will find by studying a map of the mine drawn to scale; the amount of coal in that mine where the vein of coal is 7 feet thick; the number of tons mined from it in one day and in a year; the amount of coal that must be left in the mine to support the weight of the earth above it; the probable life of the mine; the wages paid to the miners and the small number of days they work in a year; and the amount of money the railroads receive for hauling this coal, the distances they carry it, and the money they lose when there is a strike.
In other chapters you will learn some of the ways in which boys and girls in the city earn money and what careful records they keep in order to know how much their profit is; the many ways of earning that country children have in their Pig Clubs, Corn Clubs, Dairy Clubs, and Poultry Clubs; the remarkable experiments they carry on, the records they keep, and the surprising results they reach; and the cost of your schooling, the amount that each person, on the average, pays for our schools, and the number of cents lost each day that a child is absent.
As you find the answers to these problems you may decide whether your family ought to buy its bread or make it at home, and whether or not the price of beef is too high, considering what the packers must pay for live steers. You will learn how much a good cow and a good hen should produce, and you will be able to prove the worth of such knowledge by showing the astonishing number of cows and hens that should be called only "boarders," because they produce too little to pay their way. You will see what you yourself can do toward giving coal miners more regular employment, and you will be able to convince the
people about you of the wonderful importance of vaccination.
You will have to learn much more about adding, subtracting, multiplying, and dividing before you can know and do all these things; and you will need to drill yourself a great deal on the steps that cause you trouble before your work will be quick and accurate. But you will wish to give a good deal of time to the processes of Arithmetic when they are the means by which you can discover so many interesting facts. You should master the processes so well that you will remember them the rest of your life. You may also want to remember many of the facts found in the answers to the problems. Watch to see how they compare in interest and value with those you learn in history and geography.
FRANK M. MCMURRY