306 SPARKS FROM A GEOLOGIST'S HAMMER. 



I desire to direct the attention of readers of the Tribune 

 to another set of facts with which they are all familiar. 

 I suppose the first notion of a vehicle for transporta- 

 tion by water may have been suggested to primeval 

 man by the discovery that a floating log would bear his 

 weight. Astride of such a ship, our ancestors may have 

 paddled from shore to shore of their inland waters. We 

 find an atavistic recurrence, or perhaps persistence, of 

 this mode of navigation among the modern Australians. 

 The discovery could not have been long delayed, however, 

 that the buoyancy of the log would not be diminished by 

 scooping out its interior and giving it improved capacity 

 for passengers and freight. So the " dug-out 11 came into 

 existence, a form of water-craft so well adapted to the 

 "conditions of [naval] existence" among many tribes of 

 our North American Indians, that it survives as the fit- 

 test form of naval architecture. From the dug-out to the 

 seal-skin ki/ak or the bark canoe, is but a step, and this 

 step is an advance which seems to grow out of surround- 

 ing conditions. The Eskimo has no logs, but many skins; 

 and the Chippewayan has, from the birch, a bark (whence 

 certain vessels are still called " barks ") more serviceable 

 than logs or skins. These modifications of the primitive 

 craft are obviously determined by the conditions of ex- 

 istence. And so the skin 7 on the mill-pond comes into 

 existence in correlation with the lumber pile on the 

 bank; and the brave, stout life-boat is bred by the many 

 buffetings of a stormy surf; just as the biremes and tri- 

 remes of the ancients came from the long-continued 

 strain of the smaller boats by excessive loading and fre- 

 quent swampings. All these forms of rowing craft sus- 

 tain, admissibly, homological relations to each other, and 



