XX Proceedings. [February 2/f.tli, 1914.. 



equator should be zero, eight independent determinations were 

 thus available, which gave for North minus South a mean of 

 E= +o'54o + o'oo6 in km. per second. A marked difference 

 between the rotational behaviour of the two solar hemispheres 

 thus seems to be definitely established for the epoch of observa- 

 tion. 



A second result claimed from these observations concerns the 

 latitude law expressing the retardation of the revolutions away 

 from the equator. It is impossible to fit in the present series 

 with the usually accepted formula 



V= (a - b?>m-<f))co?,<p, 

 where the second term inside the brackets introduces the retar- 

 dation. A positive third term is necessary, as in a formula 



V= {a - (^sin'^ + fsin(^)cos9!) 

 which, with suitable constants, agrees very well with the values 

 of F observed at the latitudes (p. 



Possibly the fact that all the spectrograms were taken within 

 a short interval of time is the cause of the appearance of this 

 term. In earlier investigations, all of which extended over a 

 much longer range of dates, the term may have been eliminated 

 by yet unknown, more or less periodical processes regulating 

 the velocities. 



General Meeting, March loth, 1914. 



The President, Mr. Fr.^ncis Nicholson, F.Z.S., 

 in the Chair. 



Miss Eva Hibbert, Assoc. M.S.T., Demonstrator in 

 Chemistry, The Municipal School of Technology, Manchester, 

 was elected an Ordinary Member of the Society. 



