of the Black Sea and Caspian Sea. 367 
take excursions in the Caucasus, which lasted from the 17th of 
August to the 3d of October, and during which they measured 
the Kasbeck, a peak as high as Mount Blane. They resumed 
their labours on the 4th of October, and continued them follow- 
ing the 'Terek to the delta which it forms in throwing itself into 
the Caspian Sea. The highest point in this operation was 
only 594 metres above the Taman Island. In the vicinity of 
Mosdock, one of the stations, and 250 wersts from the Caspian 
Sea, the plain was on the level of the Black Sea. 
This first measurement was made under very favourable cir- 
cumstances, and gave for the difference of level 105 metres by 
which the Caspian Sea is lower than the Black Sea. 
Struck with the singularity of this result, Messrs. Parrot and 
Engelhardt recommenced the operation of the 10th of October, 
but proceeding on this occasion from east to west and following 
the same stations, withoit turning towards the Caucasus. On 
the 14th of October they had already gained the mouth of the 
Kubar. The weather during this second measurement was 
much less favourable, the barometer and thermometer were in- 
constant, the changes more sudden, the winds more variable 
and of more unequal strength. . Snow also fell at various times ¢ 
the sky was generally stormy, cold, and rainy, circumstances 
which usually render the altitudes too small. Now it is remark- 
able that it is in fact in this respect that the second determina- 
tion is erroneous, for it gives 92 metres for the elevation of the 
level of the Black Sea over that of the Caspian Sea. i 
After having thus twice traversed the great Steppe, M. Par- 
rot had the patience to make a third Journey. He set out from 
Taman on the 24th of November, and ought to have arrived at 
the mouth of the Terek on the 10th of December. The want 
of post horses produced so many delays, however, that he did 
_ not reach the banks of the Caspian Sea until the 20th of De- 
cember at 15 minutes past 11 A.M. M. Engelhardt had finished 
his observation on the Black Sea the night before: thus this’ 
operation presents no corresponding observations, and may mere- 
ly serve as a verification. On combining the observation of 
Taman of the 19th at 15 minutes past 11 with the ebservation 
made next day at the same hour in the Caspian Sea, we find 99 
metres for the difference of level. Another observation made 
at Taman in the afternoon of the 19th of December gave 102 
metres. On comparing the observation of M. Parrot of the 20th 
with the mean of all the observations of the 19th on the Black 
Sea, we shall obtain almost the sanie difference. There isin 
short no barometrical observation from that of 15 minutes past 
11 made at Taman from the 11th to the 19th of December, 
which combined with the single observation of M. Parrot of 
the 
