214 FKAGMENTS OF SCIENCE. 



Charpentier, Studer, and others. With characteristic 

 vigour Agassiz grappled with it, extending his obser- 

 vations far beyond the domain of Switzerland. He 

 came to this country in 1840, and found in various 

 places indubitable marks of ancient glacier action. 

 England, Scotland, Wales, and Ireland he proved to 

 have once given birth to glaciers. He visited Grlen 

 Eoy, surveyed the surrounding neighbourhood, and 

 pronounced, as a consequence of his investigation, the 

 barriers which stopped the glens and produced the 

 parallel roads to have been barriers of ice. To Mr. 

 Jamieson, above all others, we are indebted for the 

 thorough testing and confirmation of this theory. 



And let me here say that Agassiz is only too likely 

 to be misrated and misjudged by those who, though 

 accurate within a limited sphere, fail to grasp in their 

 totality the motive powers invoked in scientific inves- 

 tigation. True he lacked mechanical precision, but he 

 abounded in that force and freshness of the scientific 

 imagination which in some sciences, and probably in 

 some stages of all sciences, are essential to the creator 

 of knowledge. To Agassiz was given, not the art of 

 the refiner, but the instinct of the discoverer, and the 

 strength of the delver who brings ore from the recesses 

 of the mine. That ore may contain its share of dross, 

 but it also contains the precious metal which gives 

 employment to the refiner, and without which his 

 occupation would depart. 



Let us dwell for a moment upon this subject of 

 ancient glaciers. Under a flask containing water, in 

 which a thermometer is immersed, is placed a Bunsen's 

 lamp. The water is heated, reaches a temperature of 

 212, and then begins to boil. The rise of the ther- 

 mometer then ceases, although heat continues to be 

 poured by the lamp into the water. What becomes of 



