226 Analyses of Books. [Sepr. 
substantiated by their superior steadiness ; by the unerring cer- 
tainty with which they may be directed to the wished-for star; 
by the opportunity they afford us of examining any star at its 
most advantageous situation ; by the uniformity in the appear- 
ance of the compound stars, which they present to the eye and 
position of the observer, thereby materially assisting him in sub- 
sequent observations ; and, lastly, by the facility which they 
afford to the dispatch of business.” 
A letter from Professor Gauss, dated Observatory, Gottingen, 
and addressed to Mr. Herschell, the Foreign Secretary, gives an 
account of “ the new Meridian Circle at Gottingen,” constructed 
by the celebrated artist Reichenbach. It is adapted at once for 
a transit, and for the measurement of altitudes, and possesses (in 
common with the most perfect meridian telescopes) all the 
adjustments requisite for their purpose. The telescope is tive 
Paris feet in focal length, and four Paris inches in aperture. The 
four eye-pieces magnify respectively 68, 86, 120, and 170 times. 
The cross wires consist of seven vertical and two horizontal 
spider-threads. The intervals between the former are each tra- 
versed by an equatorial star in 14”. The horizontal onés are 
only 76 asunder. The axis, 35 Paris inches in length, carries 
on one side two concentric circles whose outer surfaces (or those 
furthest from the telescope) lie nearly in one plane. The exte- 
rior circle (which being fastened on the axis, revolves with the 
telescope), bears the divisions which are to every three minutes. 
The inner, or altdade circle, would turn freely about the axis, 
were it not for a clamp fastened on the pillar. This allows it 
only a small delicate motion for the purpose of adjusting the level 
fastened upon it. On this alidade circle are the four indices, 
each 45° from the vertical line, with their verniers ; which sub- 
divide the principal division into 90 parts each, and consequently 
from 2” to 2”, and yet smaller parts admit of estimation, The 
diameter of the circle where the reading-off takes place is 35 
Paris inches. That both circles, without being in actual con- 
tact, are yet separated by an interval scarce perceptible, and that 
in consequence, the microscopes for reading-off are purposely 
set somewhat obliquely, the surface of the dividing circle stand- 
ing out alittle, although but extremely little beyond that of the 
alidade circle, are adjustments which this instrument possesses 
in common with others by the same artist. Such, with the addi- 
tion of a few unimportant particulars, is the account of this valu- 
able instrument. Ofits great correctness striking instances are 
furnished by tne observations of M. Gauss ; but we think it right 
not to extend this article further than to insert the following 
notice, by the Foreign Secretary: “‘ A point which has occu- 
pied the attention of astronomers for some years, though it 
involves only a few seconds, is yet of the highest importance, 
both in reference to the art of astronomical observation, and on 
account of the numerous astronomical elements, whose exact 
