Curiosities of Science. 109 



form the focus of the sun's rays in the midst of a mass of ice. 

 A portion of the ice was melted, but the surrounding parts 

 shone out as brilliant stars, produced by the reflection of the 

 faces of the crystalline structure. On examining these bril- 

 liant portions with a lens, Professor Tyndall discovered that 

 the structure of the ice had been broken down in symmetrical 

 forms of great beauty, presenting minute stars, surrounded by 

 six petals, forming a beautiful flower, the plane being always 

 parallel to the plane of congelation of the ice. He then pre- 

 pared a piece of ice, by making both its surfaces smooth and 

 parallel to each other. He concentrated in the centre of the 

 ice the rays of heat from the electric light ; and then, placing 

 the piece of ice in the electric microscope, the disc revealed 

 these beautiful ice-flowers. 



A mass of ice was crushed into fragments ; the small frag- 

 ments were then placed in a cup of wood ; a hollow wooden 

 die, somewhat smaller than the cup, was then pressed into the 

 cup of ice-fragments by the pressure of a hydraulic press, and 

 the ice-fragments were immediately united into a compact cup 

 of nearly transparent ice. This pressure of fragments of ice 

 into a solid mass explains the formation of the glaciers and 

 their origin. They are composed of particles of ice or snow ; 

 as they descend the sides of the mountain, the pressure of 

 the snow becomes sufficiently great to compress the mass into 

 solid ice, until it becomes so great as to form the beautiful 

 blue ice of the glaciers. This compression, however, will not 

 form the solid mass unless the temperature of the ice be 

 near that of freezing water. To prove this, the lecturer cooled 

 a mass of ice, by wrapping it in a piece of tinfoil and ex- 

 posing it for some time to a bath of the ethereal solution of 

 solidified carbonic-acid gas, the coldest freezing mixture known. 

 This cooled mass of ice was crushed to fragments, and sub- 

 mitted to the same pressure which the other fragments had 

 been exposed to without cohering in the slightest degree. 

 Lecture at the Royal Institution^ 1858. 



ANTIQUITY OF GLACIEES. 



The importance of glacier agency in the past as well as 

 the present condition of the earth, is undoubtedly very great. 

 One of our most accomplished and ingenious geologists has. 

 indeed, carried back the existence of Glaciers to an epoch of 

 dim antiquity, even in the reckoning of that science whose 

 chronology is counted in millions of years. Professor Ramsay 

 has shown ground for believing that in the fragments of rock 

 that go to make up the conglomerates of the Permian strata, 

 intermediate between the Old and the New Red Sandstone, 

 there is still preserved a record of the action of ice, either in 



