304 Royal Astronomical Society. 
the difficulty of the problem, that up to the present time no person 
since Lagrange seems to have suggested or hoped for any means of 
removing it. M. Hansen has laid before us the result of his first 
trial in the case of the comet of Encke, and the comparison of his 
computed perturbations with those made by Encke by mechanical 
quadratures, proves the accuracy of the method as well as the easy 
application of it. We may be allowed to express a hope that we 
shall be soon in possession of the method itself, which we are thus 
far entitled to regard as a most brilliant conquest over one of 
the residual difficulties of physical astronomy. ‘The Council cannot 
refrain from congratulating the meeting on the above proofs that 
the science which we especially cultivate is still advancing ; that 
each year adds something to our stock of previous knowledge of 
the constitution of the universe, and that, too, of an importance 
that marks the zeal and the talent with which, both at home and 
abroad, preparations are making for the complete solution of the 
few most interesting problems which yet remain to us. 
The Council have great pleasure in drawing the attention of the 
meeting to the very valuable present which the Society has recently 
received from Admiral Greig, one of our members, and a distin- 
guished officer in the Russian navy. This consists of an altitude 
and azimuth instrument, by M. Reichenbach* of Munich. The 
diameter of the azimuth circle is 15, and of the altitude circle 12 
inches. The divisions, which are upon silver, read to 4!’ of space 
by 4 verniers upon each circle. The instrument is one of the kind 
which admits of repetition both in the horizontal and vertical 
planes, and is furnished with two telescopes ; the principal one 
resting in Ys attached to the azimuth index, and the other placed 
below the azimuth circle, according to the ordinary arrange- 
ment. But a peculiarity deserving especial notice is the manner in 
which the usual difficulty of observing near the zenith is obviated. 
A diagonal reflector, in this case a prism, directs the rays through 
one of the pivots of the transit axis, in which the diaphragm and 
eye-piece are consequently placed, and thus the observer remains 
in an easy, unaltered position, whatever may be the altitude of the 
object observed. It is almost superfiuous to add, that the gradua- 
tion, axes, tangent screws, and other delicate parts of this instru- 
ment, exhibit all the proofs of care and skill for which the maker 
was so long celebrated. 
The Council feel confident that the meeting will unite with 
them in a warm expression of their thanks to Admiral Greig, not 
only for his munificent present, but also for the proof he has thus 
given, that, though at a distance, he still looks upon us and our 
proceedings with that interest and regard which are doubly grate- 
ful as coming from an absent friend. 
* In the Notice for January 1843, Article IIL, [Phil. Mag. pres. vol. 
E 231.] the instrument is erroneously stated to haye been made by M. 
rtel. 
