200 Miscellanies. 
By a letter from Sig. Murio Gemellaro to the Editor, dated, Ni- 
olosi upon Etna, March 24, 1834, it appears that ‘‘ Etna continued 
silent.” 
13. A new Observatory at St. Petersburgh.—An observatory, 
far surpassing in magnitude every similar establishment, is about to 
be built at St. Petersburgh, by command of the Emperor. The 
observatory itself will consist of three towers with moveable cu- 
polas. ‘Two of these towers are to be appropriated to the Ko- 
nigsberg heliometer, and the Dorpat refractor ; but the center tower 
is destined for the reception of an instrument exceeding in size all 
others of the kind. In the lower part of the towers, the meridian 
and transportable instruments will be placed. Spacious habitations 
for five astronomers will be connected by two corridors with these 
towers ; so that the whole will form a continuous building, five hun- 
dred and ten feet in length. Smaller subordinate buildings for vari- 
ous purposes, will increase the establishment, for the site of which, 
an eminence, between six and seven miles from St. Petersburgh, has 
been selected.—Atheneum, Sept. 1834. 
Information requested respecting the variation of the Magnetic 
Needle.—lIt is a matter of very considerable importance to the cause 
of science, that the variation of the magnetic needle in every part of 
the globe should be accurately known. The labors of Halley, Yates, 
_Hansteen and Barlow have added much to our knowledge on this 
subject ; but it must have been observed by every one who has ex- 
amined their charts, that the lines of equal variation through this 
country are laid down with little attention to minute accuracy. In- 
deed it is believed that sufficient observations have never been pub- 
lished to furnish the materials for a complete magnetic chart of the 
United States. An effort is now making to supply this deficiency ; 
and it is urgently requested of Surveyors, of Philosophers, and all in 
this country who are interested in the subject of magnetism, to com- 
municate for this Journal any observations they have made for deter- 
mining the present variation of the needle at their respective places. 
Any observations made in former years at the same places, will also 
be valuable for determining whether the variation is increasing or di- 
minishing, and at what rate. 
