Symud i'r prif gynnwys

458 Old Price's Remains. halves of the same thing are equal" by Axiom 7th, as sure as every half of a penny will be a halfpenny. But the question is, what is the thing we have divided ? One of the Marys has just told me that all the right angles in the world are the halves of 130 degrees. This is true; but must be explained before it can be understood by tvery one of you. Some one hit upon a very nice method of measuring all angles, i.e., expressing their comparative extent, width, stride, or "value." This was, to fix a com¬ pass into the point of the angle, and make a circle cutting its legs ; which it is sure to do, whether it is a large or small circle, because you already know the said legs are much longer than even those of that naughty Edward the First, who used them to kick the poor Bards out of Wales. He (the Geometer, mind, not his Majesty) then graduated the circle, or divided it into degress ; so that the number of degrees between the legs would shew how big one angle was compared with another. Thus, an angle whose legs took in 20°, would be double one of only facing lo°, and so on. But, how many degrees must he have ? There is no " must" in the case; and it would not signify so very much how many, if all the world would only agree to use the same number. Now, suppose it was divided, as the face of a watch and clock are, into 60 degrees. Then, if the circle was cut into two halves by a horizon¬ tal line, there would be 30 degrees in each half; and if a line were drawn upwards, from the middle of this line "perpendicular" to it—i.e., so as to make the angles on each side equal—they would be what are called " right angles"; and, each of them would be half of 30, i.e., 15 de¬ grees. And, of course you would also have two right angles below the line, which would be halves of the other 30 : So the four right angles would take up the whole circle, and