PKOCEEDINGS 



OF THE 



Cambridge ^ Ijibsopljkal Sorklj . 



October 21, 1878. 

 Professor G. D. Liveing, President, in the Chair. 



Mr S. H. Vines, B.A., Christ's College, Mr F. C. Lambert,PB.A., 

 Downing College, and Mr F. B. de M. Gibbons, B.A., Gonville and 

 Cains College, were balloted for and duly elected Fellows of the 

 Society. 



The following communication was made to the Society : — 

 Dr Pearson, On a series of lunar distances. 



The object of this paper is to discuss a series of Lunar distances 

 taken during the years 1875-7, with the view of inviting fresh at- 

 tention to an old and hitherto not quite satisfactory problem. 



The entire series consists of 250 distances : of these only 200 

 are considered in this paper. They were taken for the most part 

 in the grounds of Emmanuel College, and a small number at 

 Abington, a short distance from Cambridge. 



By referring to Vol. ii. of the Society's Proceedings,^^. 414 — 18, 

 a full description will be found of the instrument, and of the kind 

 of errors which suggested farther investigation: it need only be 

 mentioned here that the first place of observation is situate as 

 nearly as possible in 52" 12' 10" N., 0^^ 0"' 29^ E.; the second in 

 52° 7' N. and O'^ 0™ 5G-*E. by the one-inch map. All the obser- 

 vations taken in the hrst spot, and a few of those taken in the 

 second, were immediately referred to a Chronometer, rated partly 

 by the Post Office Telegraph, partly by the Society's clock as set 

 by the time of the Observatory : and though these two data do 

 not exactly coincide, the discrepancy on this account cannot have 

 amounted to more than 4 or 5 seconds. Of the observations taken 

 at Abington, most depend on a fairly going watch, corrected by 



Vol. hi. Pt. v. 13 



