﻿66 Pro/. J. Milne — On the Flotation of Icebergs. 



that bergs exist at all approximating to that of a pinnacle standing 

 upon a base, the depth to which they may extend below the surface of 

 the water is less than the height tve see above, and therefore in many- 

 cases, when we see a berg 300 feet above the water, we may with 

 much reason assume that its depth beneath the surface of the water 

 is less than 300 feet. 



The case which I have considered is one which appears to be 

 applicable to many icebergs, and, I think, to the generality of them. 



It now remains to see how far such views may be carried, and 

 also, for the sake of illustration, to consider the possible conditions 

 under which some other forms of ice may be regarded as existing. 



In the paper where the conclusion just referred to was arrived 

 at, a cone approximating to a berg of ice was drawn as floating with 

 its base downwards. The Kev. O. Fisher (Gteol. Mao., 1876, p. 379) 

 has, however, raised the question of the stable equilibrium of such 

 a cone, which he thinks would not remain in the position as figured, 

 but must turn over, "Whether this would or would not be the case 

 with the cone in question, I am not prepared to answer. The figure 

 is only drawn to illustrate the calculation to which it is appended. 

 As a practical illustration, to strengthen these views and to show that 

 the cone of ice which I have taken will not float with its base 

 downwards, Mr. Fisher takes a tetrahedron out of a set of models 

 of crystals, and placing it in water finds that it floats with one of its 

 angles downwards. 



This I consider to be an unfair comparison, which no doubt has 

 led many casual readers to the belief that a cone will also float with 

 its apex downwards, and perhaps, in consequence, that my con- 

 clusions, being founded on false assumption, must also of necessity 

 be false. Lest readers should be led into misconceptions of this 

 sort, it may be well to consider how cones of ice would float. 



First, if we take a slab of ice and place it upon water, we know 

 that it will float horizontally. On the middle of this slab we might 

 raise a small pinnacle of ice, and the mass would still keep horizontal. 

 We might next increase this pinnacle round its sides without increas- 

 ing its height until we reached the edges of our slab, and still we 

 may imagine the block we have built up keeping its horizontal 

 position. We should here have a figure approximating to the 

 probable shape of an iceberg which has travelled into latitudes like 

 those of Newfoundland, — a pinnacle supported on a foot or pedestal. 

 Such a form approximates to a cone, and such a cone I believe would 

 float, and does float with its base downwards, or in other words, 

 from a consideration of this sort, it is evident to us that there are 

 certain obtuse cones which would float with their apex upwards. 

 Secondly, on the other hand, if I make a very acute or tall cone, it 

 would never for a moment be expected to float vertically with its 

 base downwards more than a tall stick of ice would be expected to 

 retain such a position. Such a cone would, according to ordinary- 

 expectation and according to all probability, fall on its side and float 

 more or less horizontally. It is also equally certain that such a 

 cone would not float with its apex downwards, as Mr. Fisher's ex- 

 periment might lead one to think. 



