Septembbe 18, 1914] 



SCIENCE 



397 



inator 294. It would be still more inter- 

 esting if the two instruments could be set 

 up on meridians in different parts of the 

 earth. The Cape and a northern observa- 

 tory, Upsala for example, would furnish 

 one arc; Harvard and Arequipa or Santi- 

 ago another. If it were possible to connect 

 by triangulation Australia with the Asiatic 

 continent, a third could be obtained near 

 the meridian of Brisbane. Or, accepting 

 the observed parallax and the earth's ellip- 

 tieity, we could find by observation the 

 lengths of long arcs on the earth's surface 

 with high accuracy. 



In any case, I believe that the time must 

 shortly come when the photographic method 

 of finding the moon's place should be taken 

 up more extensively, whether it be used for 

 the determination of the moon's parallax 

 and the earth's ellipticity or not. The 

 Greenwich meridian observations have 

 been and continue to be a wonderful store- 

 house for long series of observations of the 

 positions of the sun, moon, planets and 

 stars. In the United States, Harvard Ob- 

 servatory has adopted the plan of securing 

 continuous photographic records of the sky 

 with particular reference to photometric 

 work. Under Professor Pickering it will 

 also continue the photographic record of 

 the moon's position as long as arrange- 

 ments can be made to measure the plates 

 and compute the moon's position from them. 



In spite of the fact that Harvard Ob- 

 servatory has undertaken to continue for 

 the present the work of photographing the 

 moon's position, I believe that this method 

 should find a permanent home in a national 

 observatory. It has already shown itself 

 capable of producing the accuracy which 

 the best modem observations of Greenwich 

 can furnish, and no higher praise need be 

 given. If this home could be found in the 

 southern hemisphere, and more particularly 

 in Australia, other advantages would 

 accrue. 



But we should look for more than this. 

 In an observatory whose first duty might 

 be the securing of the best daily records of 

 the sky, the positions of the sun, stars, 

 planets, a couple of plates of the moon on 

 every night when she is visible would be a 

 small matter. What is needed is an organ- 

 ization so constructed as to be out of the 

 reach of changing governmental policy with 

 a permanent appropriation and a staff of 

 the highest character removed from all 

 political influences. It could render im- 

 mense service to astronomers, not only in 

 the Empire but all over the world. The 

 pride which every Englishman feels who 

 has to work with the records of the past 

 furnished by Greenwich would in course of 

 time arise from the work of a similar estab- 

 lishment elsewhere. Those of us who live 

 in a community which, reckoning by the 

 age of nations, is new, know that, in order 

 to achieve objects which are not material, 

 sacrifices must be made ; but we also know 

 that such sacrifices are beneficial, not only 

 in themselves, but as exerting an indirect 

 influence in promoting the cause of higher 

 education and of scientific progress in every 

 direction. In saying this I am not advo- 

 cating the cause of the few, but of the 

 majority; the least practical investigations 

 of yesterday are continually becoming of 

 the greatest practical value to-day. 



No address before this section is complete 

 without some speculation and a glance to- 

 wards the future. I shall indulge in botii 

 to some small extent before closing. I have 

 shown you what the outstanding residuals 

 in the moon's motion are: they consist 

 mainly of long-period fluctuations in the 

 mean longitude. I have not mentioned the 

 secular changes because the evidence for 

 them does not rest on modem observations 

 but on ancient eclipses, and these are 

 matters too debatable to discuss in the 

 limited time allotted to me for this address. 

 It may be said, however, that the only 



