196 NATIONAL ACADEMY OF SCIENCES 



short time, after which he was appointed Superintendent of the 

 Nautical Almanac. Not long afterwards, in 1859, he was given 

 charge of the mathematical department in the Naval Academy at 

 Annapolis, but at the outbreak of the Civil War, he again re- 

 sumed the office of Superintendent of the Nautical Almanac in 

 Cambridge. During the years in which he was connected with 

 this office he made many contributions to mathematics and 

 astronomy, the most important of which was his series of tables 

 of Mercury. 



In 1866 Professor Winlock was appointed Professor of 

 Astronomy in Harvard College and Director of the Harvard 

 Observatory. 6 Here he exerted himself in strengthening the 

 equipment of the observatory by the addition of many important 

 instruments and aids to astronomical work. The transit circle 

 of the observatory, a costly instrument, had proved unsatisfactory, 

 and Winlock succeeded in obtaining funds from friends of the 

 Observatory to replace it. To arrange for the construction of the 

 new instrument, he visited the principal observatories in Europe 

 in 1867. He also devised improvements which were afterwards 

 adopted by other astronomers. Between 1871 and 1875, 30,000 

 observations were made with this instrument, under Winlock's 

 direction. 



In 1869, Professor Winlock was appointed head of a party to 

 cooperate with the Coast Survey in observing the total eclipse of 

 the sun in Kentucky. On this occasion he succeeded in making 

 the first photograph of the solar corona made during any eclipse. 

 At the request of the Superintendent of the Coast Survey, he 

 organized and led the party sent to Spain to observe the total 

 eclipse of the sun occurring on December 22, 1870. During this 

 eclipse a telescope of long focus, fixed horizontally, and without 

 an eyepiece, which was devised by Winlock for photographic 

 work, was used by all the observers. 



Winlock devised many improvements in spectroscopic instru- 

 ments, and also in 1872 greatly improved and extended the time- 



5 At a later date he also held the position of Professor of Geodesy in the Lawrence and 

 Mining Schools of Harvard College. 



