1870.] 69 [Perry. 



a wintry mass ; and that the so-called counter-facts are equally sus- 

 ceptible of explanation according to the glacier theory, we surely 

 have the best kind of demonstration possible in the nature of the 

 case. Should this prove to be the fact, though he could only just 

 touch the points now, the glacier theory must be regarded as far more 

 than an empty hypothesis, and the various forms of its so-called demo- 

 lition may be counted for nought. 



Another objection claiming notice is the alleged weight of author- 

 ity against the glacier explanation. Von Buch, the greatest geolo- 

 gist of the age, it is urged, entirely discarded this hypothesis. The 

 same is true of other eminent and able investigators. This argument 

 might be good, if eminent men had never done foolish things. The 

 opinions of distinguished savants have presumptive evidence in their 

 favor, so long as there is nothing against them, and they are to be 

 received not as their dicta, but because they are reasonable. While 

 we are to have due respect for their legitimate decisions, we are also 

 to remember that in some cases their judgments are not worth a 

 straw ; that we are to recognize only the weight of their evidence as 

 authority. In given points and under certain circumstances the 

 ablest investigators have made the grandest mistakes. Most people, 

 after passing a given age, cling tenaciously to the theories they 

 adopted when they were younger. Early manhood is the perio d of 

 inspiration. It is because young men are constantly coming upon 

 the stage that the world moves. When a little older, these same 

 persons, with rare exceptions, stand in the way of progress, and it 

 must be confessed that in so doing they sometimes exert a whole- 

 some influence, and sometimes — not. Now Von Buch (for whom he 

 had a high veneration) was already somewhat advanced in years, 

 and had his predilections fixed, when the youthful Agassiz first 

 advanced the glacier theory in explanation of the drift phenomena. 

 It is not therefore surprising that he, and other eminent geologists 

 similarly situated, rejected, and have continued to reject it, outright. 



Several other objections urged have respect to the conditions sup- 

 posed to be necessary to the existence and action of glaciers. These 

 are evaporation, congelation, and inclination. As these favorable 

 conditions occur in Switzerland, so do ice-streams as their result. 

 And the implication is that these favorable conditions have hot 

 existed in New England, and consequently that the theory of an 

 extensive ice-sheet moving over the region is a myth. Now he would 

 not say that the same conditions existed here in the past as are now 



