The first started in 1735, under the command of Marine-Lieutenant Prontschischev. After having sailed down the river, and passed, on the 14th August, the eastern mouth-arm of the Lena, he sailed round the large delta of the river. On the 7th September he had not got farther than to the mouth of the Olonek. Three weeks had thus been spent in sailing a distance which an ordinary steamer ought now to be able to traverse in one day. Ice was seen, but not encountered. On the other hand, the voyage was delayed by contrary winds, probably blowing on land, whereby Prontschischev's vessel, if it had incautiously ventured out, would probably have been cast on the beach. The late season of the year induced Prontschischev to lay up his vessel for the winter here, at some summer yourts built by fur-hunters in 72 deg. 54' N.L. The winter passed happily, and the following year (1736) Prontschischev again broke up, as soon as the state of the ice in Olonek Bay permitted, which, however, was not until the 15th August. The course was shaped along the coast toward the north-west. Here drift ice was met with, but he nevertheless made rapid progress, so that on the 1st September he reached 77 deg. 29' N.L., as we now know, in the neighbourhood of Cape Chelyuskin. Compact masses of ice compelled him to turn here, and the Russians sailed back to the mouth of the Olonek, which was reached on the 15th September. The distinguished commander of the vessel had died shortly before of scurvy, and, some days after, his young wife, who had accompanied him on his difficult voyage, also died. As these attacks of scurvy did not happen during winter, but immediately after the close of summer, they form very remarkable contributions to a judgment of the way in which the Arctic expeditions of that period were fitted out. A new expedition, under Marine-Lieutenant Chariton Laptev, sailed along the same coast in 1739. The Lena was left on the 1st August, and Cape Thaddeus (76 deg. 47' N.L.) reached on the 2nd September, the navigation having been obstructed by drift ice only off Chatanga Bay. Cape Thaddeus is situated only fifty or sixty English miles from Cape Chelyuskin. They turned here, partly on account of the masses of drift ice which barred the way, partly on account of the late season of the year, and wintered at the head of Chatanga Bay, which was reached on the 8th September. Next year Laptev attempted to return along the coast to the Lena, but his vessel was nipped by drift ice off the mouth of the Olonek. After many difficulties and dangers, all the men succeeded in reaching safely the winter quarters of the former year. Both from this point and from the Yenisej, Laptev himself and his second in command, Chelyuskin, and the surveyor, Tschekin, the following year made a number of sledge journeys, in order to survey the peninsula which projects farthest to the north-west from the mainland of Asia.