Letters of Euler to a German Princess, on Different Subjects in Physics and Philosophy Volume 1
Leonhard Euler
Paperback
(RareBooksClub.com, May 9, 2012)
This historic book may have numerous typos and missing text. Purchasers can download a free scanned copy of the original book (without typos) from the publisher. Not indexed. Not illustrated. 1802 Excerpt: ...it is said, that gold is 19 times heavier than water, we mean, that having two equal masses, the one of gold, the other of water, that which is of gold will have 19 times the weight of that which is of water. When we thus express ourselves, we fay nothing of the absolute weight of bodies, we only speak by way of comparison, and with a reference always to masses of an equal size. Neither is it of importance, whether the size be great or small, provided they be equal. 35/A Aug, 1760. LETTER XLVII. Terms relative to Gravity, and their true Import. f? RAVITY, or weight, seems, so essential to the-nature of bodies, that it is almost impossible to form the idea of a body divested of this quality. And it's influence is so universal, in all our operations upon body, that we must, in every instance, pay attention to it's gravity, or weight. As to our own persons, whether we stand, sit, or lie, we continually feel the effect of the gravity of our own body; we could never fall, if the body were not, as well as all it's parts, endowed with this force. Language itself is regulated according to this property of bodies. The place toward which a body tends ia it's descent, we term low; and the opposite direction from the body, we term high. It must be remarked, that when a body, in falling, is at perfect liberty, it always descends in a straight line, pursuing which, it's direction is said to be downward. This line is likewise called vertical, by which term we always mean a straight line, drawn from high to low; and if we conceive this line produced upward, till it reaches heaven, we call that point in the heavens our zenith, an Arabian word, denoting that point in the heavens which is directly over our head. You comprehend, then, that a vertical line, is that straight lin...