WORK IN SUMMER OF I84I. 321 



and a warm-hearted man, with a thread of 

 humor running through his dry good sense, 

 which made him a very amusing and attractive 

 companion. 



As it was necessary, in view of his special 

 programme of work, to penetrate below the 

 surface of the glacier, and reach, if possible, 

 its point of contact with the valley bottom, 

 Agassiz had caused a larger boring appara- 

 tus than had been used before, to be trans- 

 ported to the old site on the Aar glacier. 

 The results of these experiments are incorpo- 

 rated in the " Systeme Glaciaire," published 

 in 1846, with twenty-four folio plates and 

 two maps. They were of the highest inter- 

 est with reference to the internal structure 

 and temperature of the ice and the penetra- 

 bility of its mass, pervious throughout, as it 

 proved, to air and water. On one occasion 

 the boring-rod, having been driven to a depth 

 of one hundred and ten feet, dropped sud- 

 denly two feet lower, showing that it had 

 passed through an open space hidden in the 

 depth of the ice. The release of air-bubbles 

 at the same time gave evidence that this gla- 

 cial cave, so suddenly broken in upon, was 

 not hermetically sealed to atmospheric influ- 

 ences from without. 



VOL. I. 21 



