071 the Moiion of Glaciers. 405 



to the subject would involve an extent of writing and printing 

 not only incompatible with the limits of the Philosophical Ma- 

 gazine, but of the patience of the most determined reader. 



But in point of fact such readers are few indeed. Mathe- 

 matical and mechanical controversies (especially if either party 

 has the dexterity to make them turn, as a last shift, upon the 

 metaphysic of a term) are known, by sad experience, even to 

 have outlived their originators, and to have been bequeathed 

 to a second generation, without the world being a whit the 

 wiser, or the combatants approaching mutual conviction. 

 And in our own days of bustle and emulation it may be taken 

 for granted that siic/i controversies are absolutely unread, 

 except by the parties and one or two partizans, at least when 

 they have reached the first rejoinder. 



1 disclaim, therefore, the intention of entering into contro- 

 versy with Mr. Hopkins, although far from saying that I will 

 not defend my opinions against his, so far as tliey shall really 

 be found to differ. But this I will do by an independent as- 

 sertion of facts and observations and reasonings, which shall 

 tend to the advancement of truth, as well as to the exposure of 

 error on the part of others. 



If we deduct from Mr. Hopkins's writings twenty-eight 

 pages of a paper written on the Theory of Glaciers before he 

 had made himself personally acquainted with the great fads 

 about which he had to reason, there remain eighty-nine pages 

 of matter before us. To enter into a controversy would, there- 

 fore, require an analysis of these. I will briefly state a few 

 reasons, independent of the mere extent of the controversy, 

 which seem to exempt me from a collision with Mr. Hopkins 

 upon every point which he has thought it proper to discuss. 



1. On account of the fluctuations of opinion they contain. 

 If there be any, beside myself, who have read the whole of 

 these eighty-nine pages, they know that, as regards many 

 opinions and assertions, it would be easy to place Mr. Hop- 

 kins at issue with himself. Fortunately we are not altogether 

 left to the interpretation of algebraical symbols and of English 

 words, for both of these admit of much dexterity in their qua- 

 lification, but the author has clothed his views in the earlier 

 stage of authorship in diagrams sufficiently plain to admit of 

 no dubiety. Of course, 1 only complain that Mr. Hopkins, 

 whilst altering his opinions, does not allovv that he is con- 

 vinced by the arguments opposed to them. The first rigour 

 of his views underwent some plastic change when my Travels 

 appeared ; and in proportion as his attention was forced to the 

 mechanical theory there presented, they assumed successively 

 a more and more ductile form ; the very notions of plasticity 



