Professor Elias Loomis. 439 



Kendall were using its instruments. Professor Harriett bad 

 built the observatory at West Point, and had began to observe 

 there. Lieutenant Gilliss after years of excellent work in the 

 little establishment on Capitol Hill had just finished the present 

 Naval Observatory building- at Washington, Professor Mitcbel 

 had began to build the Cincinnati Observatory, and the 

 •rgetown Observatory building bad been erected. Pro- 



sor Looniis's work at Hudson should be measured by what 

 others were doing at the time, rather than by the larger per- 

 formance of to-day. 



In the summer of 1844, the year in which Professor Loomis 

 came to New York, a new method in Astronomy had its first 

 beginnings. The telegraph line had just been built between 

 Baltimore and Washington, and Captain Wilkes at Baltimore 

 compared his chronometer by telegraph with one at Wash- 

 ington, and so determined the difference of longitude of the 

 two places. 



Professor Bache was now Superintendent of the Coast 

 Survey, and he determined at once to use the new method 

 for the purposes of the survey. To Mr. Sears C. Walker was 

 committed the direction of the work, but scarcely less impor- 

 tant Avere the services of Professor Loomis, who for three 

 campaigns had charge of the end of the lines in Jersey City 

 and New York. Their first partially successful efforts were 

 made in 1846, but the practical difficulties were overcome and 

 entire success was obtained by them in 1847 and 1848. In 

 these years the differences of longitude of Washington, Phila- 

 delphia, New York and Cambridge were thus determined 

 with an accuracy far greater than any previous similar deter- 

 mination whatsoever. 



The next summer, that of 1849, Professor Loomis assisted 

 in a like work to connect Hudson, Ohio, with the eastern sta- 

 tions. His observations of moon culminations at Hudson were 

 thus available equally with those made at Philadelphia, Wash- 

 ington, Dorchester and Cambridge for determining the abso- 

 lute longitudes of Atlantic stations from Greenwich. It was 

 not until 1852 that European astronomers began to use these 

 telegraphic methods in measuring longitudes. 



In 1850 Professor Loomis published a volume on the Recent 



