ANNIVERSAEY ADDRESS OF THE PRESIDENT. Hii 



tions seems to be necessary to the validity of the calculations on 

 which Sir "W. Thomson lays so much stress. 



Nevertheless it surely may be urged that such affirmative ansvfers 

 are purely hypothetical, and that other suppositions have an equal 

 right to consideration. 



For example, is it not possible that, at the prodigious temperature 

 which would seem to exist at 100 miles below the surface, all the me- 

 tallic bases may behave as mercury does at a red heat, when it refuses to 

 combine with oxygen ; while, nearer the surface, and therefore at a 

 lower temperature, they may enter into combination (as mercury does 

 with oxygen a few degrees below its boihng-point) and so give rise 

 to a heat which is totally distinct from that which they possess as 

 cooling bodies ? And has it not also been proved by recent re- 

 searches that the quahty of the atmosphere may immensely affect its 

 permeability to heat, and consequently profoundly modify the rate 

 of cooling of the globe as a whole ? 



I do not think it can be denied that such conditions may exist, 

 and may so greatly affect the supply and the loss of terrestrial heat 

 as to destroy the value of any calculations which leave them out of 

 sight. 



My functions as your advocate are at end. I speak vtdth more 

 than the sincerity of a mere advocate when I express the belief that 

 the case against us has entirely broken down. The cry for reform 

 which has been raised without, is superfluous, inasmuch as we have 

 long been reforming from within with all needful speed. And the 

 critical examination of the grounds upon which the very grave 

 charge of opposition to the principles of Natural Philosophy has 

 been brought against us rather shows that we have exercised a vdse 

 discrimination in declining to meddle with our foundations at the 

 bidding of the first passer-by who fancies our house is not so well 

 built as it might be. 



