276 SIR RODERICK I. MURCHISON’S ADDRESS— RUSSIA. [May 24, 1858. 
meridian was extended to one of 25° 20' 8"*2, reaching from Ismail 
on the Danube to Hammerfest on the northern shores of Europe. 
The length of this line, according to Struve’s calculations, amounts 
to 1,447,786*78 toises. The chief meridian of the whole arc is that 
of Dorpat, which was accurately connected by chronometrical expe- 
ditions in 1854 with Pulkowa ; the latter place having been pre- 
viously connected by Struve in the years 1843 and 1844 with the 
observatory of Greenwich. The longitude of Dorpat Observatory 
thus obtained is l h 46 m 53 s, 53 east of Greenwich. 
One of the results of these operations is the very exact determi- 
nation of a line of altitudes through Europe from South to North ; 
and not the least striking fact among them is, that the Black Sea, 
the Baltic, and the Polar or North Atlantic Sea at Hammerfest, 
occupy exactly the same level. 
Not less interesting is the Eussian measurement of the arc of 
parallel or latitude extending from Bessarabia in the west, to the 
mouth of the Volga on the east. Of this work very little is known 
out of Eussia ; but the following reliable remarks have been fur- 
nished by Mr. Petermann, who obtained them from correspond- 
ents in that country. The mean parallel of these measurements is 
that of Ziiganesht, or 47° 30 1 North latitude, extending from Bes- 
sarabia, west of the Dniestr, by Vosnezensk on the Bug ; ITshkalka 
on the Dniepr to Melekhovsk on the Donetz ; thence it turns more 
towards north-east, reaches the left bank of the Volga at Sarepta, and 
extends along that river as far as Astrakhan. The elevations of this 
line are of great interest : from Ziiganesht, which is 1004 feet above 
the sea, the ground gradually descends as far as the Dniepr, on 
which Snamenka has an altitude only of 223 feet. Between this 
point and Kuznetsow the country rises to 825 feet at Medwad, and 
beyond Kuznetsow presents a general level of 400 to 560 feet, till at 
Sarepta it suddenly descends from 427 feet to 63 feet, which re- 
markable descent was already shown by myself and colleagues in our 
work on the Geology of Eussia. The line of measurement along the 
Volga first descends below the level of the Black Sea at Prishivinsk. 
This work being in connexion on the west with the Trigonometrical 
Surveys of Austria, Prussia, and France, the determination of a 
very considerable arc of parallel between the Atlantic shores and the 
Caspian Sea is thus established. 
Along with these operations may be mentioned the recent con- 
clusion of a very important line of trigonometrical observations 
extending from Stavropol across the Caucasus to Tiflis, Bayazid, 
