232 Notices respecting New Books. 



" That the comparative abundance or paucity of stars in any par- 

 ticular region of the northern hemisphere, so far as visible in our 

 latitudes, has reference to its situation in respect of the Milky Way, 

 is a proposition which the researches of Sir William Herschel have 

 sufficiently established, not merely by the general aspect of the heavens 

 when viewed with the naked eye, but also when examined with 

 powerful telescopes in a mode which may properly be called statis- 

 tical, — that is to say, by counting the number of stars in the field of 

 view of one and the same telescope at a great number of given points 

 in the concave of the heavens, and so estimating their comparative 

 populousness in stars, in their different districts. The results of a 

 system of observation of this nature have, as is well known, con- 

 ducted him to the highly remarkable and interesting conclusion 

 above-mentioned, and to this further consequence, that all the stars 

 visible to us, whether by unassisted vision, or through the best tele- 

 scopes (such at least as are scattered, or not congregated in resolvable 

 nebulse, or globular or similar highly condensed clusters), belong to 

 and form a part of a vast stratum, or considerably flattened and un- 

 symmetrical congeries of stars in which our system is deeply, though 

 excentrically plunged, and, moreover, situated near a point where 

 the stratum bifurcates or spreads itself out into two sheets." 



It may be readily supposed that the opportunity of carrying out 

 this great induction by similar observations in the southern hemi- 

 sphere was not neglected ; and accordingly, so soon as a knowledge 

 of the regions where nebula? might more especially be expected had 

 been acquired, or where, without too much risk of missing such ob- 

 jects the sweeps might be interrupted for the purpose of gauging, — 

 i. e. of counting the number of visible stars in determinate fields of 

 view, — a system of star- gauges was set on foot, " so as to dot over 

 the surface of the heavens as it were with a regular tesseration of 

 gauged or counted fields, disposed at regular and equal intervals of 

 right ascension and polar distance." According to the plan laid 

 down, the gauges were taken when the telescope, in the regular course 

 of sweeping, arrived at either extremity and at the middle of the zone 

 under examination, so that the intervals were 10 m of time in R.A., 

 and 1° 30' of arc in P.D. It was not indeed expected, or even con- 

 sidered possible, that so great a multitude of fields as this plan sup- 

 poses could be actually counted ; but a system of some sort was 

 absolutely necessary to prevent confusion and unequal observing, 

 and more especially to ensure an absolute impartiality in the selec- 

 tion of the gauge-points ; and it was also foreseen that many of the 

 fields would inevitably be passed over from the interference of the 

 regular and more important business of the sweep. On the whole 

 about 2300 gauges were obtained in this manner, which, though 

 leaving some blanks, afford ample materials " for testing the validity 

 of the induction in question, and for estimating the comparative rich- 

 ness of every considerable district in the southern heavens." 



After some further details relative to the mode of observing and 

 arranging the results, the author gives a " synoptic table of southern 

 star-gauges, arranged on meridians and parallels." He then proceeds 



