Address of Sir Wm. Thomson at the Glasgow Meeting. 341 
upper surface of the earth must have been at a higher tempera- 
ture than that now found at the depth of one kilometer. Such 
less than about 4000° C. It would not take much “ hurrying 
aed be quite sure the earth is solid in its interior ; not, I admit, 
‘hroughout its whole volume, for there certainly are spaces 10 
