weight which he supports himself." Harry replied, "that Tommy had
chosen that himself; and that he should directly have informed him of
his mistake, but that he had been so surprised at seeing the common
effects of a lever, that he wished to teach him some other facts about
it;" then shifting the ends of the pole, so as to support that part
which Tommy had done before, he asked him, "if he found his shoulder
anything easier than before." "Indeed, I do," replied Tommy, "but I
cannot conceive how; for we carry the same weight between us which we
did before, and just in the same manner." "Not quite in the same
manner," answered Mr Barlow; "for, if you observe, the log is a great
deal farther from your shoulder than from Harry's, by which means he
now supports just as much as you did before, and you, on the contrary,
as little as he did when I met you." "This is very extraordinary
indeed," said Tommy; "I find there are a great many things which I did
not know, nor even my mamma, nor any of the fine ladies that come to our
house." "Well," replied Mr Barlow, "if you have acquired so much useful
knowledge already, what may you expect to do in a few years more?"

Mr Barlow then led Tommy into the house, and showed him a stick of about
four feet long, with a scale hung at each end. "Now," said he, "if you
place this stick over the back of a chair, so that it may rest exactly
upon the middle, you see the two scales will just balance each other.
So, if I put into each of them an equal weight, they will still remain
suspended. In this method we weigh every thing which is bought, only,
for the greater convenience, the beam of the scale, which is the same
thing as this stick, is generally hung up to something else by its
middle. But let us now move the stick, and see what will be the
consequence." Mr Barlow then pushed the stick along in such a manner,
that when it rested upon the back of the chair, there were three feet of
it on one side, and only one on the other. That side which was longest
instantly came to the ground as heaviest. "You see," said Mr Barlow, "if
we would now balance them, we must put a greater weight on the shortest
side; so he kept adding weights, till Tommy found that one pound on the
longest side would exactly balance three on the shortest; for, as much
as the longer side exceeded the shorter in length, so much did the
weight which was hung at that end require to exceed that on the longest
side."

"This," said