Pike's illustrated descriptive catalogue of optical, mathematical and philosophical instruments Volume 1; manufactured, imported, and sold by the ... affixed at which they are offered in 1848 ... - Softcover

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. 1848 Excerpt: ...would furnish us with rules for finding a weight, which, being accumulated uniformly in the circumference, a b c d, would exert an inertia equal to that of the wheels. But as the figures are wholly irregular, recourse must be had to experiment for the discovery of such a weight. For this purpose a weight of thirty grains was affixed to a silk line which did not weigh one-quarter of a grain; this line being wound round the wheel, the weight of thirty grains, by descending from rest, communicated motion to the wheel, and, by many trials, was observed to describe a space of thirty-eight and a half inches in three seconds. From these data we find the mass equivalent to the inertia to be two ounces and three quarters. This is a mass equivalent to the inertia of the wheel, abed, and the frictipnwheels together. The resistance to motion, therefore, arising from the wheel's inertion will be the same as if it were absolutely removed, and a mass of 2f were accumulated in the circumference of the wheel, abed. This being premised, suspend the pieces, or brass boxes, A, B, by a silk line passing over the wheel, abed, and make them balance each other; now, if I add any weight, To, to A, so that it shall descend, the exact quantity of matter moved will be ascertained, for it will Be A added to B, added to To, added to 2J oz. Mr. Atwood proves in his work, t that the following formula will give the required mass.£--=P x where p signifies the weight, 30 gr.; t the time, 3 seconds; d the space described by a body in a second, 16 feet 1 inch, or 193 inches; s the space described by the body, 38.5 inches; and x the iuertia sought. That is in figures for the present case, 3 o m H I 9--30 equal to 1323 grains, or 2 3-4 oz. »s In order to avoid troublesome computations ...