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3. Professor Forbes then read the following Letter from 

 Professor Gordon, of Glasgow, also on the subject of 

 the Viscous Theory of Glaciers. 



Glasgow, January 31. 1845. 



* * * When you requested me to give you a niemoranduni of 

 what appeared to me to be the vety glacier- like motion and appearance 

 of Stockholm pitch flowing from a barrel, I considered my observation 

 to have been too casual to be worth writing, and having foreseen that 

 I could arrange an experiment at Gateshead in the beginning of the 

 year, I delayed giving you the memorandum you wished. I had 

 hoped to have been able to inspect and report on my experiment 

 about this time ; but I cannot go to Gateshead for some time to come, 

 nor have I had any report of the progress of my pitch glacier since 

 the 6th January, when I was informed it had not moved since the 

 day after I left it, on the 28th December. Your note of yesterday 

 induces me to off'er you the following still perfectly vivid impressions 

 of the analogy between ice and Stockholm pitch. 



Allow me, in the first place, to mention that I read your travels in 

 the Alps, in May last. That on the 24th of June I spent almost 

 20 hours on the glaciers of the Grindewald. I went up by the 

 lower glacier, prepared with poles to prove the motion, and actually 

 observed a progress of about 12 inches in the course of 13 hours, 

 from 6 A.M. to 7 p.m. I traced the " dirt bands" on the surface. 

 I was let down into several crevasses, one of them to a depth of 30 

 feet and could trace the statu structure of the ice. The alternate 

 clear blue thin veins, and the transition to opaque grey or even 

 white. I descended from the glacier with a much better appreciation 

 of the theory of glaciers than I had had, and a strong conviction 

 that the facts I had observed, could not be otherwise accounted for 

 than by the mechanical theory you have given. In passing through 

 Gateshead in August, a broken headed barrel of Stockholm pitch at 

 the Wire Rope Factory, attracted my attention. Its general appear- 

 ance is represented in Fig. 1. 



A mass of Stockholm pitch broken from a barrel in August (at 

 the time of the observations I am about to mention) presented a dark- 

 brown colour, a glassy lustre, translucent edges. The substance is 

 fragile, fracture conchoidal, and very uniform. A mass, Fig. 4., 

 which was brought to me by the workman having charge of this 

 department, and which he had broken from the end of such a 

 stream as I have represented coming from the barrel, presented 

 generally the same appearance as a mass broken from an entire 



