654 REPORT — 1900. 



(nve an annual mean of 34'83 ins. ; and 55 stations for the southern group, 

 Cheshire, Derbyshire, Nottingham, and Lincoln, give an annual mean of 26'58ins. 

 In the first group the driest months are April, mean 2-41 ins., and June, 2-36 ins. ; 

 in the second group the driest months are February, mean 2"17 ins., and April, 

 2' 18 ins. ; and in the third group the same months are the driest, February with a 

 mean of 1"81 in., and April with 1'79 in. In the first group the wettest month is 

 November, mean 4-60 ins. ; in the second group the wettest month is October, 

 mean 3'75 ins. ; and in the third group the same month is the wettest, with a 

 mean fall of 3-20 ins. 



Nottingham and Lincoln are the driest counties throughout the year, except in 

 February, when Durham is the driest, and in May, when Durham and Northumber- 

 land are drier than Nottingham. Cumberland and Westmoreland are the wettest 

 throughout the year, Cumberland usually being the wetter of the two, but in 

 January, March, October, November, and December the greatest diflerence between 

 them is 05 in. 



The mean and extreme annual rainfall at each station are given in the complete 

 paper, with a map showing the position of the stations and their height above 

 mean sea-level. 



8. Report on Meteorological Observations on Ben Nevis. 

 See Reports, p. 46. 



9. Repoi't on recording the Intensity of Solar Radiation. 

 See Reports, p. .36. 



10. Report on establishing an Observatory on Mount Royal, Montreal. 



See Reports, p. 33. 



TUESDAY, SEPTEMBER 11. 

 The following Eeport and Paper were read : — 

 1. Report on Electrolysis and Electrochemistry. — See Reports, p. 34. 



2. A Discussion on ' Ions ' tvas opened by Professor G. F. FitzGerald. 



3. The Radiation of a Black Body on the Electromagnetic Theory. 

 By H. C. PocKLiNGTON, M.A., D.Sc. 



There are two methods that may be used to solve the problem, the direct and the 

 indirect method, via KirchhoS''s laws. The latter seeins preferable, as, on account 

 of the freedom of choice of a substance, the mathematical work may be simplified 

 by choosing the simplest kind of substance. 



The substance here chosen is a gas, supposed to consist of atoms carrying 

 electric charges. As a preliminary the question whether any result can be 

 obtained from the data is investigated by the method of ' dimensions,' and the 



formulae 

 and 



are found. 





