3o6 POrULAK LECTURES AND ADDRESSES. 



tinned freezing of the lava, be bridged across by 

 solid rock thick enough in proportion to breadth 

 not to break clown and sink. There would again 

 be breaking away of the piers and upheavals of the 

 liquid material below ; but by degrees the honey- 

 combed mass would become nearly like a solid 

 throughout with comparatively small interstices of 

 liquid lava. This is in part the view of Hopkins. 

 On account of arguments drawn from the 

 phenomena of precession and nutation he was led 

 to regard the earth as rigid on the whole ; and 

 looking to the existing evidence as to geological 

 phenomena he was led to hold a view of the 

 probable history of the earth agreeing with that 

 which I have sketched, at all events so far as it 

 would lead to the supposed present honeycombed 

 condition. 



Hopkins considered other very important 

 questions, and among these was the question of 

 the influence on their condition as to solidity and 

 fluidity, of the great pressure to which the interior 

 parts of the globe arc subjected. He made 

 experiments as to the influence of pressure on the 



