42 



Prof. James Thomson 



[Mar. 10, 



March 10, 1892. 



The LORD KELVIN, President, followed by the Treasurer, in the 



Chair. 



A List of the Presents received was laid on the table, and thanks 

 ordered for them. 



The Bakerian Lecture was read by the President on behalf of the 

 Author as follows : — 



Bakerian Lecture.—" On the Grand Currents of Atmospheric 

 Circulation." By James Thomson, LL.D., F.R.S., Emeritus 

 Professor of Civil Engineering and Mechanics in the Uni- 

 versity of Glasgow. Keceived March 10, 1892. 



[Plate 1.] 

 (Abstract.) 



In this paper a historical sketch is given of the progress of observa- 

 tional and theoretical researches into the nature and causes of the 

 Trade Winds and other great and persistent currents of atmospheric 

 circulation. Mention is made of the fanciful attempts at explanation 

 by Dr. Martin Lister and by Dr. Garden in papers submitted to the 

 Royal Society a little more than 200 years ago, and which are to be 

 found recorded in the ' Philosophical Transactions.' These papers 

 give evidence of the scanty and crude condition of knowledge and 

 speculation on the subject in the early years of the Royal Society ; but 

 yet they may probably have had a beneficial effect in instigating 

 Edmund Halley, the astronomer, to communicate to the Royal 

 Society, in 1686, a paper on the " Trade Winds and Monsoons,"* 

 bringing together a systematized collection of observational results, 

 accompanied by theoretical considerations. That paper constituted 

 an important step in the development of the science of the subject, 

 even though his theory, in one of its most important parts, that which 

 relates to the east to west motion of the trade winds, which he 

 attributed to the diurnal revolution round the equatorial zone of the 

 maximum of accumulation of heating effect, turns out to be funda- 

 mentally untenable. 



Halley's paper was followed, forty-nine years later, by one more 

 * « Phil. Trans.,' No. 183, p. 153. 



