"One thing more," added Mr Barlow, "as we are upon this subject, I will show you." So he led them into the yard, to the bottom of his granary, where stood a heavy sack of corn. "Now," said Mr Barlow, "if you are so stout a fellow as you imagine, take up this sack of corn, and carry it up the ladder into the granary." "That," replied Tommy, laughing, "is impossible; and I doubt, sir, whether you
could do it yourself." "Well," said Mr Barlow, "we will, at least try what is to be done." He then led them up into the granary, and, showing them a middle-sized wheel, with a handle fixed upon it, desired the little boys to turn it round. They began to turn it with some little difficulty, and Tommy could hardly believe his eyes, when, presently after, he saw the sack of corn, which he had despaired of moving, mounted up into the granary, and safely landed upon the floor. "You see," said Mr Barlow, "here is another ingenious contrivance, by which the weakest person may perform the work of the strongest. This is called the wheel and axle. You see this wheel, which is not very large, turns round an axle which goes into it, and is much smaller; and at every turn, the rope to which the weight is fixed that you want to move, is twisted round the axle. Now, just as much as the breadth of the whole wheel is greater than that of the axle which it turns round, so much greater is the weight that the person who turns it can move, than he could do without it." "Well," said Tommy, "I see it is a fine thing indeed to acquire knowledge, for by these means one not only increases one's understanding, but one's bodily strength. But are there no more, sir, of these ingenious contrivances, for I should like to understand them all?" "Yes," answered Mr Barlow, "there are more, and all of them you shall be perfectly acquainted with in time; but for this purpose you should be able to write, and comprehend something of arithmetic."
Tommy.—What is arithmetic, sir?
Mr Barlow.—That is not so easy to make you
understand at once; I will, however, try to explain it. Do you see the grains of wheat which he scattered in the window?
Tommy.—Yes, sir.
Mr Barlow.—Can you count how many there are?
Tommy.—There are just five-and-twenty of them.
Mr Barlow.—Very well. Here is another parcel; how many grains are there?
Tommy.—Just fourteen.