94 ASPECTS OF AMERICAN ASTRONOMY. 



way have strengthened an erroneous impression that the seat of impor- 

 tant astronomical work is necessarily connected with an observatory. 

 It must be admitted that an institution which has a local habitation 

 and a magnificent building commands public attention so strongly that 

 valuable work done elsewhere may be overlooked. A very important 

 part of astronomical work is done away from telescopes and meridian 

 circles and requires nothing but a good library for its prosecution. 

 One who is devoted to this side of the subject may often feel that the 

 public does not appreciate his work at its true relative value from the 

 very fact that he has no great buildings or fine instruments to show. I 

 may therefore be allowed to claim as an important factor in the Ameri- 

 can astronomy of the last half century an institution of which few have 

 heard and which has been overlooked because there was nothing about 

 it to excite attention. 



In 1849 the American l^autical Almanac office was established by a 

 Congressional appropriation. The title of this publication is somewhat 

 misleading in suggesting a simple enlargement of the family almanac 

 which the sailor is to hang up in his cabin for daily use. The fact is 

 that what started more than a century ago as a nautical almanac has 

 since grown into an astronomical ephemeris for the publication of 

 everything pertaining to times, seasons, eclipses, and the motions of 

 the heavenly bodies. It is the work in which astronomical observa- 

 tions made in all the great observatories of the world are ultimately 

 utilized for scientific and public purposes. Each of the leading nations 

 of western Europe issues such a publication. When the preparation 

 and publication of the American ephemeris was decided upon the office 

 was first established in Cambridge, the seat of Harvard University, 

 because there could most readily be secured the technical knowledge 

 of mathematics and theoretical astronomy necessary for the work. 



A field of activity was thus opened, of which a number of able young 

 men who have since earned distinction in various walks of life availed 

 themselves. The head of the office, Commander Davis, adopted a policy 

 well fitted to promote their development. He translated the classic 

 work of Gauss, Theoria Motus Corporum 0a4estium, and made the 

 office a sort of informal school, not, indeed, of the modern type, but 

 rather more like the classic grove of Hellas, where philosophers con- 

 ducted their discussions and profited by mutual attrition. When, after 

 a few years of experience, methods were well established and a routine 

 adopted, the office was removed to Washington, where it has since 

 remained. The work of preparing the ephemeris has, with experience, 

 been reduced to a matter of routine which may be continued indefi- 

 nitely, with occasional changes in methods and data and improvements 

 to meet the increasing wants of investigators. 



The mere preparation of the ephemeris includes but a small part 

 of the work of mathematical calculation and investigation required 

 in astronomy. One of the great wants of the science to-day is the 



