52 Onthe Transit Instrument in determining Latitude. 
are in the meridian of Irkutsk and extending through Mant- 
chooria southwards, through the Chinese empire, as well as the 
Atlantic States of the American Union* will give us the smallest 
meridian of the earth with the same accuracy, corresponding to 
the determination of the greatest, which passes through Hastern 
Europe (Kostromo, Stawropol, Erzerfim). Still, much requires 
to be done. The continuation of the Russian Survey through 
Turkey, and if possible to Hastern Africa, would be most import- 
ant; and Struve has already (in 1857) advocated it in the Paris 
Academy. The opposite part of this greatest meridian passes 
over the icy deserts of North Western America and the group 
of islands known as the Marquesas, and hence afford no possi- 
bility of its completion on that side. 
After this article was printed, the writer received the account 
of the New British Survey and notice of the correction of a 
small error of computation. This induced him to reprint some 
of the sheets on which the numerical results are given as above. 
It will hardly be necessary to add anything in praise of the 
author. |T'o bring up a question of such importance is suffi- 
ciently praiseworthy in itself, but the writer has done more; he 
has opened the way to a final determination and has given it, at 
least in its general aspect. We shall rejoice if this interesting 
subject calls other powers into the field to labor further in this 
direction. Corrections like those which the writer has made for 
Dorpat and Warsaw will be required for many other places, and — 
each comparison of this kind furnishes its share to the final de- 
termination. MADLER, 
“ays 
Art. VIL—On the Transit Instrument as a substitute for the 
Zenith Telescope in determining Latitude, and on the Latitude of — 
New Haven ; by Prof. C. 8. Lyman. 
THE method of determining latitude by measuring micromet- : 
rically the difference of meridional zenith distances of stars on — 
