366 On the relative Heights of the Levels 
always made between six in the morning and eight in thé 
evening. 
It may be easily supposed from all these precautions that M. 
Parrot must have calculated his operation with great care: thus 
he made use of the formula of M. Laplace aud of the coefficient 
18393 metres which M. Ramond had found in the Pyrenees, 
almost under the very same parallel with the Caucasus, having 
in view at the same time the capillary depression of the mercury. 
"Phe only correction of which he could not keep an account was 
that of the diminution of gravity. 
The number of stations comprehended between the mouth of 
the Kuban and that of the Terek is 51; they w ere,'therefore, 
distant from each other about 18 wersts or 13 miles. The first 
measurement commenced on the 13th of July, beginning with 
the island of Taman*, and proceeding eastward, ascending the 
Kuban to Batal-Paschiisk near Constantinogorks, where the 
29th station was. Our travellers set out from this point to 
* The isle of Laman is remarkable by its springs of asphaltus, and its 
foaming volcanoes, which have been partly described sby Pallas in his 
Travels of 1793 and 1794. >Messrs. Parrot and Engelbardt visited the 
small volcanoes situated between the city of Taman and the lake Sucur. 
On the slope of a hill they discovered two basins of 16 metres aperture 
and two metres and a half deep, and which were filled with a frothy mass 
formed of argil and water. From time to time they saw rise to the sur- 
face of cach crater a bubble of air about a foot in diameter: the instant 
it burst a great number of similar small balls took its place. This pheno- 
menon was repeated every $0 or 40 seconds. The temperature of the 
water differed little from that of the air: the water at 29°49 of the centi- 
grade thermometer, the thermometer in the sun marked 2°999, and in the 
shade 26°9°. The travellers wanted proper instruments for examining the 
nature of the air extricated by the crater; they merely ascertained “that 
a was not inflammable, and that it did not keep up combustion. ‘She water, 
which was yellowish, had a saltish taste: in the bottom were found frag- 
ments cf bituminous limestone, selenite, and quartzous freestone. It seems 
that these small basins underwent some considerable changes at the time 
of the great eruption which took place in 1794 in the northern part of the 
bay of Taman. In 1807 near Kurgan the Cossacks heard a subterraneous 
noise similar to a discharge of artillery. The mountain was enveloped 
with a thick smoke; but speedily they saw issue s/owly from the bowels of 
the yawning earth a new hill, as large as a house. Large masses of cal- 
careous stone were thrown about here and there, but no flame was per- 
ceived. In the vicinity near Bugos, fountains of asphaltus or liquid mi-+ 
neral tar were found, which issue from secondary layers of freestone aud 
schistous limestone. 
These phenomena of frothy volcanoes put us in mind of that of Cuma- 
eatar, on the coast of Paria; the argillaceous and impregnated plains of 
Chapapote (asphaltus and petroleum) of the Island of Trinity; the foaming 
volcanoes of Girgenti in Sicily, celebrated by the ancients; and particularly 
the volcanoes of Turbace, near Carthagena in New Spain, and which 
according to M. Humboldt send forth azotic gas much purer thau is 
generally obtained in the laboratories of the chemists. 
make 
