LOUIS AGASSIZ 75 



The erratic boulders which were scat- 

 tered over Switzerland were to be sorted, 

 mapped, traced back, every one, to the 

 quarry whence it came ; and the same 

 was to be attempted on a less complete 

 scale for other regions outside Switzer- 

 land. Agassiz's own volume was to be 

 a study of the glacier itself, as in action 

 to-day ; and many experiments on the 

 grinding, crawling mass were made with 

 boring - holes, coloured liquids intro- 

 duced into the ice, and rows of stakes 

 set across the glacier to show by their 

 deflection the rate of flow and place of 

 swiftest current in the unwieldy river, 

 whose complicated motions in its ir- 

 regular channel were often exactly op- 

 posed to expectation. But nothing ac- 

 complished on the physical side could 

 compare in importance with what was 

 ascertained on the historical side. Ag- 

 assiz could soon recognise traces of 

 glacial action as a hunter knows the 

 marks of his game. In his first visits to 



