Annals of philosophy Volume 28 - Softcover

Reseña del editor

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. 1826 edition. Excerpt: ...would allow. But the micrometric measurement proved that that was not the case. That evening the major axis, A, was 44".75; the minor axis, B, was 41".72; and the diameter in question taken with the same micrometer was 42"-34. Calling this diameter x, and the latitude on the planet, I, we have x = r-r aQd the numerical result is x = 42"-38, (A" sin.2 J+ B« cos." I) differing only 0".04 from the measurement. Most probably it is the slanting position of the axes of the ellipse, with regard to the vertical circle, which causes this illusion. Lastly, there was terminated on the same evening, an "Account of some Observations made with a Twenty-feet Reflecting Telescope, by J. F. W. Herschel, Esq. Sec. RS. and For. Sec. of this Society." This valuable communication is divided into four sections. The first contains descriptions and approximate places of 300 new double and triple stars. The telescope with which the observations were made, is one of the "front view" construction; aperture 18 inches, focal length 20 feet. It was constructed in the year 1820, under the joint superintendence of Mr. Herschel and his venerable father. Its light, with its full aperture, enables it to reach the faintest nebulae of the third class, while, with an aperture of 10 or 12 inches, it serves to define double stars of the first class of an average degree of closeness. Mr. Herschel briefly describes the method of differences employed in sweeps of the heavens, the modifications introduced into the process on account of Mr. Herschel's being deprived of the valuable assistance of his aunt, Miss Caroline Herschel, his classification and characteristics of the magnitudes of the stars from the 7th to the 20th...