Notices respecting New Books. 233 



to examine how far the induction before alluded to is borne out by 

 the observations, for which purpose the following process was insti- 

 tuted. The poles of the great circle marking the medial line of the 

 Milky Way were first found, their places being ascertained to be 

 in h 47 m R.A. and 116° 0' N.P.D. for the southern pole, and 12 h 

 47 m R.A. and 64° 0' N.P.D. for the northern. To this great circle, 

 which Sir John happily designates the Galactic circle, a series of 

 parallels were drawn on an 18-inch globe, dividing the heavens 

 into zones of 15° each in breadth, and the points of intersection of 

 these with the meridians, taken at intervals of twenty minutes, were 

 read off in N.P.D. by the aid of the brass meridian arc, and trans- 

 ferred to a chart containing the actual projections of all the observed 

 gauges. These points were then connected by regular curves, which 

 are consequently the projections of the series of parallels above- 

 mentioned, or the galactic parallels, the spaces between them being 

 the projections of the zones into which they divide the surface of the 

 sphere. This done, the next step consisted in counting the number 

 of fields of view actually laid down on the charts, and in adding 

 into one sum the number of stars observed. The following are the 

 results obtained : — 



" In the oval representing the circle of 15° radius surrounding the 

 southern pole of the galactic circle were found to have been observed 

 43 fields, containing in all 260 stars, which gives for the average 

 density of stars in this region of the heavens, 6*05 stars to a field of 

 15' in diameter, visible in the 20-foot reflector with the usual sweep- 

 ing power 180. 



" In the zone comprised between the parallels of 15° and 30° ga- 

 lactic south polar distance 144 gauges were found to occur, con- 

 taining an aggregate of 953 stars, or 6*62 stars to a field. 



" In the zone comprised between 30° and 45° were observed 218 

 gauges, containing 1980 stars, which gives an average of 9*08 stars 

 to a field. 



" In the zone from 45° to 60° were found 375 gauges containing 

 5060 stars, being 13*49 stars to a field. 



"From 60° to 75° were found to have been observed 472 gauges 

 containing 12409 counted stars, whence the average of 26*29 stars 

 to a field. 



" From 75° to 90°, being the zone immediately adjacent to the 

 Milky Way on the south side, and containing half its breadth, 442 

 gauges are registered containing 26105 stars. Among these occur 

 some gauges in which the stars are set down as * innumerable ' or so 

 crowded as to be impossible to count them without bestowing more 

 time and care than the nature of the object in view was judged to 

 require. These are taken when they occur at 200 stars to the field, 

 which is certainly not an excessive estimate. There are, however, 

 not above five or six gauges in this predicament. The average den- 

 sity of stars in this zone, according to the numbers above stated, is 

 59 : 06 to a field. 



" A zone of 3° in breadth bisected throughout by the galactic 

 circle, or extending 14 on its north and as much on its south side, 



Phil. Mag. S. 3. Vol. 33. No. 221. Sept. 1848. R 



