National Geographic : 1890 Apr
Telegraphic Determinationsof Longitude. impact on the ink well. Had there been time for more extensive experiment this difficulty might have been overcome. Or if the same method had been adopted at both stations, the result would have been affected by only the difference between the times of movement of the brass spring which would have been minute. Lack of time for experiment, and the fact that the observers were averse to introducing untested methods into a chain of measure ments most of the links of which were already completed, prevented any use being made of this achievement. The meas urement between Greenwich and Lisbon being satisfactorily completed. Lieut. Com. Green by order of the Navy Depart ment returned to the United States, and the links between Rio and Pernambuco and between the latter place and Para, were measured by Lieut. Corn. Davis and the writer, completing the work of the expedition, after which the party returned to Washington. The computation of this work, showed the somewhat surprising fact that the heretofore accepted position in longitude of Lisbon, differed from the true one by about two miles. The longitude of Rio Janeiro had always been more or less in doubt, various deter minations had differed by as much as nine miles, but the position finally decided upon by the best authorities agreed very closely with that obtained by telegraph. The next expedition was sent out by the Bureau of Navigation to China, Japan and the East Indies, Lieut. Coin. Green being still in charge. The officers composing the party sailed from San Francisco by mail steamer in April, 1881, for Yokohama, where they joined the U. S. Steamer Palos. From Hong Kong north to Vladivostok in Eastern Siberia the cables were owned by a Danish company. From Hong Kong to the south and west they were the property of English companies. Beginning at Vladi vostok observations were made at all stations on the Asiatic coast except Penang, as far as Madras, India. It was intended to try and make some use of the automatic method of receiving time signals, on this work, but on arriving in Japan it was found that the recording instrument used by the Danish company was entirely different from that used by the English lines. It con sisted of a series of electro-magnets acting on a single armature, which carried a siphon made of silver. The signals consisted of long and short movements, to one side of the middle line, instead of equal deflections on both sides as in the Thompson recorder.