750 A MEMOIR OF ELIAS LOOMIS. 



and Messrs. Walker and Kendall were using its iustrunients. Profes- 

 sor Bartlett had built the observatory at West Point, and had beguu 

 to observe there. Lieuteuant Gilliss after years of excellent work in 

 the little establishment on Capitol Hill had just finished the present 

 Naval Observatory building at Washington, Professor Mitchell had 

 beguu to build the Cincinnati Observatory, and the Georgetown obser- 

 vatory building- had been erected. Professor Loomis's work at Hudson 

 should be measured by what others were doing at the time, rather than 

 by the larger performance of today. 



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

 New Yoik, 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 tele- 

 graph with oue at Washington, and so determined the difference of 

 longitude of the two places. 



Professor Bach was now Superintendent of the Coast Survey, and he 

 determiued at once to use the new method for the puri)oses of the sur- 

 vey. To Mr. Sears C. Walker was committed the direction of the work, 

 but scarcely less important were 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 aud 1848. In these years the differ- 

 ences of longitude of Washington, Philadelphia, New York, aud 

 Cambridge were thus determined with an accuracy far greater than 

 any previous similar determination whatsoever. 



The next summer, that of 1849, Pri)fessor Loomis assisted in a like 

 work to connect Hudson, Ohio, with the eastern stations. His obser- 

 vations of moon culminations at Hudson were thus available equally 

 with those made at Philadelphia, Washington, Dorchester, and Cam- 

 bridge for determining the absolute longitudes of Atlantic stations 

 from Greenwich. It was not until 1852, that Europeon astronomers 

 began to use these telegraphic methods in measuring longitudes. 



In 1850, Professor Loomis published a volume on the "Kecent prog- 

 ress of astronomy, especially in the United States." A first and a 

 second edition was soon exhausted, and in 1856, the volume was entirely 

 rewritten and very much enlarged. Some of the topics in these volumes 

 were the subjects of articles communicated from time to time to the 

 public in the American Journal of Science, Harper^s Magazine and other 

 periodicals. Another imi)ortant contribution to astronomy appeared 

 in 1865, that is, his '• Introduction to practical astronomy." Eminent 

 astronomers in England and America have expressed in the highest 

 terms their praise of this book. Though it is now 35 years since its 

 first appearance, and many treatises on the same subject, some elab- 

 orate and some elementary, have since been published, yet for an in- 

 troduction to practical work I believe that a student will find this vol- 

 ume better than any other for his uses at tile beginning of his course. 



