"You are altogether too literal, and the letter killeth in carpentry as well as in Scripture," replied Mr. Brookbine. "You must apply common sense to the figures. Now look at the outside measure on the blade: find the figure for one inch. That one means one inch in length, without regard to breadth, as you define a line in geometry. Hold up the square with the tongue down. Now does the inch of length lie on the right or the left of the point marked one."
"On the right," replied a dozen.
"Now look at the point marked twenty-three: is the inch marked with this number on the right or the left of it?"
"On the right."
"But there is another inch on the left of the mark, which is the twenty-fourth inch, though there is no room to mark it uniformly with the other numbers. Now, boys, look the thing over a little before you raise an objection. I repeat that, on the outside, the blade is two feet long. The student who said his blade was marked twenty-two in one place was wrong in his fact, and if he looks again he will see that the inside length of the blade is twenty-two and a half inches, which is the outside width less the width of the tongue.
"In these squares the tongue is sixteen inches long, on the outside, and fourteen on the inside, marked in the same manner as the blade. The inside length is two inches less than the outside, for the blade is two inches wide, while the tongue is only an inch and a half. You must know the square so that you can use it without stopping to study out its meaning.
"The tongue is sixteen inches long in this instance because it furnishes a convenient measure for the placing of studs and furrings. The rule is to put studs and furrings sixteen inches apart; but there is no law which compels any carpenter or architect to follow it. Floor-joists are usually placed at the same distance apart, though the rule is often varied to meet the circumstances."
"I don't know what a furring is," said one of the boys.
"Furring a house is nailing strips of board, usually sawed at the mill three inches wide, to the posts and studs for the sides, and the floor-joist for the ceiling, on a room, at a distance of sixteen inches apart, on which the laths are nailed for the plastering. If they were placed at any other distance from each other, it would make great confusion and waste in lathing. Laths are sawed four feet in length, so as to cover the space from the middle of one furring to the middle of the third one from it. Each lath is nailed to four furrings."
"But every room can not be exactly divided into spaces of sixteen inches in its length or breadth," suggested Harry Franklin.