368 On the relative Heights of the Levels 
the 20th of December indicates a sensible difference of level 
between the two seas: the least of these determinations will not 
be less than 41 metres. 
After having ascertained this grand difference of level, eur 
travellers thought they should inquire if it had always existed. 
Now Pallas thought he recognised by the form of the strata and 
the shells of the Caspian Sea scattered throughout the Steppe 
the ancient shores of that sea. ‘The operations of Messrs. 
Parrot and Engelhardt place these shores, which have an im- 
mense development, and in which we find gnifs and bays very 
cleaily defined, at 234 metres above the present Jevel; 1t must 
therefore be admitted that a mass of water has been lost of about 
30,000 square sea leagues in surface and 100 metres in depth. 
M. Parrot does not think that this was by evaporation; for, ac- 
cording to Gmelin, the waters of the Caspian Sea are so little 
salt that they do not contain one fourth of the muriate of soda 
which is found in those of the Atlantic Ocean: he rather thinks 
that this water must have run off by rents which have been suc- 
cessively opened and closed, the bottom of the sea being agi- 
tated by the volcanic action, the effects of which are still seen 
in the Island of Taman on the Bosphorus, and at Baka on the 
Caspian Sea. ‘The enormous differences between the soundings 
observed since 1556 and the time of Peter the Great to the pre- 
sent time give some probability to this opinion *. 
Let us now refer these results to the operations of the same 
kind which have been made at different epochs in order to com- 
pare the Red Sea with the Mediterranean, the Mediterranean 
with the Atlantic Ocean, and this Ocean with the South Sea. 
During the French expedition in Egypt, a commission of 
engineers of roads and bridges was charged under the direction 
of M. Je Pere to execute the levelling of the Isthmus of Suez : 
thereby they resolved the celebrated question agitated from the 
most remote antiquity, of the elevation of the Red Sea above 
the Mediterranean and the soil of Lower Egypt. It results, in 
fact, from the labours of the commission, that the level of the 
* On taking the mean between the results of the two measurements we 
shall find 9&4 millimetres (near 200 feet) for the quantity by which the 
Jevel of the Black Sea is more elevated than that of the Caspian Sea. 
tence it results that Astracan, the adjacent plains, and a very great num- 
ber of other inhabited places as well in Persia as in Russia, are-much in- 
ferior to the level of the Black Sea and the Mediterranean :—the singularity 
of this result will justify the details into which we have entered. ‘To cove 
clude: Before the voyage of Messrs. Parrot and Engelhardt, it had been 
suspected that the two seas had always one and the same level. M. Par- 
yot’s measurement corresponds perfectly with that given by Dr. Thos. 
Young in bis Natural Philosophy. The barometrical heights of Kamyehjn 
give for the Wolga 50° 4’ of latitude, and 54} millimetres below the level 
of &t. Petersburgh, 
Mediterra- 
