Page:Sir William Herschel, his life and works (1881).djvu/180

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158
Life and Works

greater or less number of stars were visible. These were counted, and the direction in which the telescope pointed was noted. Gauges of this kind were made in all parts of the sky, and the results were tabulated in the order of right ascension.

The following is an extract from the gauges, and gives the average number of stars in each field at the points noted in right ascension and north polar distance:

R.A. N.P.D.
78° to 80°
No. of Stars.
R.A. N.P.D.
92° to 94°
No. of Stars.
h. m. h. m.
11 6 3.1 15 10 9.4
12 31 3.4 15 22 10.6
12 44 4.6 15 47 10.6
12 49 3.9 16 8 12.1
13 5 3.8 16 25 13.6
14 30 3.6 16 37 18.6


In this small table, it is plain that a different law of clustering or of distribution obtains in the two regions. Such differences are still more marked, if we compare the extreme cases found by Herschel, as R. A.