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A Celestial Atlas. a Companion to the Celestial Atlas
A Celestial Atlas a Companion to the Celestial Atlas Author:James Middleton General Books publication date: 2009 Original publication date: 1842 Notes: This is a black and white OCR reprint of the original. It has no illustrations and there may be typos or missing text. When you buy the General Books edition of this book you get free trial access to Million-Books.com where you can select from more than a million book... more »s for free. Excerpt: This change is called their proper motion, to distinguish it from their apparent diurnal revolution, caused by the earth's motion on its axis. The fixed stars, visible to the naked eye, are divided into six classes, according to their apparent magnitudes. The largest are called of the first magnitude, the next in size of the second, and so on to the sixth, which are the smallest that can usually be perceived without the aid of glasses. Those minute objects called telescopic stars, however, are likewise arranged according to their apparent size, to about the sixteenth or seventeenth magnitudes. They are immensely numerous, some hundreds, in the brightest parts of the heavens, appearing in the field of view of a telescope at one -time; and even with the most powerful instruments, which have yet been constructed, there are myriads only just perceptible ; from which we are justified in concluding, that there are vast numbers, which no instrument has yet enabled us to behold. chapter{Section 4 There are about 20 of the first magnitude, 76 of the second, 220 of the third, and the remainder of the fourth, fifth and sixth, increasing in number as they diminish in size; the whole number visible to the naked eye being about 2000. All the stars of the same class are not exactly of the same size, there being very little difference between a small star of the first magnitude and a large one of the second,« less