342 POPULAR LECTURES AND ADDRESSES. 



But to economize your time look at this second one, 

 which was placed in water last Tuesday exactly as 

 you see the first a globe. It is now like a pan- 

 cake. It has flattened itself on the surface of the 

 water to a round cake, of which the section is 

 shown approximately by Fig. 6. 1 The water was 



FIG. 6. 



slightly heated, as it would take two or three years 

 for the globe of wax to get as flat as that in cold 

 water. We have hurried it up this evening by hotter 

 water, but I am now going to leave it to itself. 



Then here is a model a wooden board having 

 its edge shaped to represent the various forms of 

 shore line, and covered with a layer of wax illus- 

 trating the Arctic ice on the viscous theory. This 

 was prepared last Monday, and has been somewhat 

 hurried up by heat. You sec the wax spreading 

 itself on the plane, and tumbling over the edges. 



1 The curve is accurate for a floating /Vv-cap, and was drawn 

 from the equation y = \> (\ -^ with b (hcight) = 2 inches, and 

 a (diameter) = 20 inches. 



