384 JAMES CLERK MAXWELL. [CHAP. XII. 



a heretical form, however, for as the Greek alphabet was 

 used up, I have used German capitals from 51 to 3 to stand 

 for Vectors, and, of course, V occurs continually. This letter 

 is called " Nabla," l and the investigation a Nablody. You 

 will be glad to hear that the theory of gases is being experi- 

 mented on by Profs. Loschmidt and Stefan of Vienna, and 

 that the conductivity of air and hydrogen are within 2 per 

 cent of the value calculated from my experiments on friction 

 of gases, though the diffusion of one gas into another is " in 

 erglanzender ubereinstimmung mit d -schen Theorie" 



To PROFESSOR W. G. ADAMS. 



Natural Science Tripos , 

 3d December 1873. 



I got Professor Guthrie's circular some time ago. I do 

 not approve of the plan of a physical society considered as 

 an instrument for the improvement of natural knowledge. 

 If it is to publish papers on physical subjects which 

 would not find their place in the transactions of existing 

 societies, or in scientific journals, I think the progress to- 

 wards dissolution will be very rapid. But if there is suffi- 

 cient liveliness and leisure among persons interested in 

 experiments to maintain a series of stated meetings to show 

 experiments, and talk about them as some of the Ray Club 

 do here, then I wish them all joy ; only the manners and 

 customs of London, and the distances at which people live 

 from any convenient centre, are very much against the 

 vitality of such sociability. 



To make the meeting a dinner supplies that solid ground 

 to which the formers of societies must trust if they would 

 build for aye. A dinner has the advantage over mere 

 scientific communications, that it can always be had when 

 certain conditions are satisfied, and that no one can doubt 

 its existence. On the other hand, it completely excludes 

 any scientific matter which cannot be expressed in the form 

 of conversation with your two chance neighbours, or else by 



1 The name of an Assyrian harp of the shape v . 



