128 MR. JOSEPH BAXENDELL 



thus removed ; while the products derived from pectine or 

 pectic acid are extracted by the copious washings with 

 water to which gun-cotton is always subjected after the 

 action of the acid is completed. The quantity of wax and 

 fatty acid contained in the fibre is too minute to produce 

 any appreciable effect after its conversion into gun-cotton. 



V. On Solar Radiation. Part I. 

 By Joseph Baxendell^, F.R.A.S. 



[Eead before the Physical and Mathematical Section, October loth, 1867.] 



Although observations of solar radiation have now been 

 regularly made for several years at various public observa- 

 tories, and by many amateur meteorologists, I am not 

 aware that any useful or important result has yet been 

 deduced from them. It seems to be generally supposed 

 that the disturbing influences which affect the indications 

 of the black-bulb thermometer are so uncertain and irre- 

 gular in their action as to render it almost hopeless to 

 expect that any new and valuable result can be obtained 

 from them. On comparing sets of observations made by 

 different observers, the most startling and discouraging 

 discrepancies are often found to exist, for which, in the 

 absence of any information as to the exact circumstances 

 under which the observations were made, it is impossible 

 to account satisfactorily. A few years ago an inquiry in 

 which I was engaged led me to undertake a discussion of 

 the Greenwich solar -radiation observations ; but the re- 

 sults proved so perplexingly anomalous and unsatisfactory, 

 that I could not venture to place any reliance upon them. 

 Having, however, recently become possessed, through the 



