The 18th century saw the Arctic coast of North America reached at two points, as well as the first scientific attempt to reach the North Pole.
With the other four he reached the coast of Egypt, on the 7th of May, only, to sight a powerful British force, and to be compelled to escape to Toulon, which he did not reach till the 22nd of July.
As regards the Peruvian boundary, an agreement was reached in 1904 to submit the dispute to the arbitration of the president of Argentina in case further efforts to reach an amicable settlement failed.
In this case the object lay upon a stage plate, whose centre had so far been made opaque, so that the rays coming from the illuminating plane mirror could not reach the objective direct, but only the rays passing the stage plate to the side of this blackened portion reached the Lieberkiihn mirror, and were used in lighting.
The command of the expedition was given to Sir Samuel Baker, who reached Khartum in February 1870, but, owing to the obstruction of the river by the sudd or grass barrier, did not reach Gondokoro, the centre of his province, for fourteen months.