Prof. John Milne — On the Form of Volcanos. 507 



character, and that this character was similar to what I have 

 already described. 



One confirmation of this identity I find by reference to my sketches. 

 Another confirmation was obtained whilst taking the angular distance 

 between several of these mountains by means of a sextant held 

 horizontally. By this I was enabled to carry the reflected image of 

 one mountain and place it in juxtaposition with the image of its 

 neighbour, the latter being seen directly. Whenever this was done 

 the similarity in the curvature of the two mountains was very 

 striking. Experiments of this sort were made at several places. 

 The first were made along the north-west shore of Paramushir, 

 where there are a number of extremely well-formed mountains. 

 The only one of these which bears a name is Mount Fuss. Another 

 well-formed mountain is the Island of Alaid. 



Curvature of hills, piles of debris, etc. — Curvatures which appear 

 to be similar to those we see upon the sides of volcanos are to be 

 seen upon the slopes of many hills, These are especially noticeable 

 upon the surface of debris lying beneath steep scarps. These curves 

 are, however, seldom to be observed. The reason is that it is only 

 rarely we can obtain their profile view. In looking at a range 

 of hills, we usually see them curving downwards towards the low 

 ground, and if we ascend them we usually remark that the climb- 

 ing becomes more difficult the higher we go up. When the slope 

 of hills like these can be looked at from the end of the range 

 instead of from the front, a peculiar curvature will be observed, and 

 this is not unlike the logarithmic curvature of volcanos. Profile 

 views of curvatures are strikingly exhibited upon the sides of 

 Hakodate Head. This is a solitary mountain at the south end of 

 Yezo, upon which the town of Hakodate is built. Its position and 

 its shape make it very like Gibraltar. It consists of a mass of 

 trachytic rock covered with alluvium. Near the top of the mountain, 

 which is more than 1,100 feet in height, the alluvium is thin, but 

 near the base it is many feet in thickness. 



From its nature it is to a large extent evidently the result of the 

 degradation of the rocks on which it rests. Materials from high 

 levels have been constantly rolling to low levels, larger stones 

 rolling farther than smaller ones, and the consequence has been that 

 from the base to near the summit long curvatures have been 

 formed. As the mountain is a solitary one, these curvatures can be 

 seen in profile, and their form is remarkably like that exhibited 

 by volcanos. 



Experiments upon the form of heaps. — In order to determine the 

 form which a heap of loose material assumes, I made several ex- 

 periments by allowing a stream of sand and gravel to fall through 

 a funnel upon a level floor. The heaps which were produced were 

 as follows : — 



1. Fine sand. — This fell from a height of about 3 feet until it formed a heap 

 27 inches high. The sides appeared to be straight, and they had a slope of 31° 30'. 



2. Fine gravel.— This fell until it formed a heap 21 inches high. The sides of 

 this were also straight, and the slope was 31° 30'. 



