264 Ml*. J. Ball on the Vemd Stfudufe of Glaciers, 



been gained by tbe continued study of the subject, whicb bag 

 induced the author of the new theory to modify very con- 

 siderably the views which he first published two years ago. 

 Having been sagacious enough to perceive the true cause of the 

 phsenomenon in question, he has been led to alter his view as to 

 the modus operandi : his theory is no longer a merely mechanical 

 one, in which it is assumed that pressure must have upon the 

 particles of glacier ice the same effect that it has upon those of 

 mud; it is now a physical theory, depending upon the known 

 properties of the particular substance of which glaciers ai'e com- 

 posed, and one capable of being directly brought to the test of 

 experiment. 



Having frankly admitted so much, I claim permission to 

 point out one or two particulars in which the chain of demon- 

 stration framed with so much knowledge and ingenuity seems 

 to me still incomplete, and to urge that there may be still some 

 residual phaenomeua in glacier structure not accounted for by 

 Professor Tyndall's theory, and capable of interpretation through 

 the action of other physical causes. 



The conclusive argument against the so-called stratification 

 theory is derived from the remarkable appearances which Pro- 

 fessor Tyndall observed last summer on the Furgge Glacier near 

 Zermatt. The situation -was one which exposed him to con- 

 siderable danger in approaching close to the ice, and the illus- 

 tration exhibited at the Eoyal Institution did not look very like 

 the ordinary veined structure ; but in the case of so bold an 

 alpine traveller, and so practised an observer, I have no doubt 

 whatever of the complete accuracy of the statement, that in that 

 place the veined structure was seen cutting through the planes 

 of the stratification of the neve, and, further, that Professor 

 Tyndall satisfied himself that this veined structure is developed 

 in a direction perpendicular to that of pressure acting on the 

 glacier. Further than this, I am quite satisfied with the accu- 

 racy of the more general statement, that in the three ordinary 

 cases in which we are able to detect the veined structure, the 

 surfaces that compose it are disposed at right angles to the 

 direction in which pressure is actually at work, or has previously 

 acted, upon the glacier ice. Is it therefore necessary to believe 

 that the veined structure is, in every case, a product of pressure 

 acting on the ice ? Upon this point I venture to retain some 

 doubts, which I desire to submit to those who may be disposed 

 to pursue, into their last recesses, the varied problems to which 

 the glaciers have given rise. I turn from the great glaciers 

 arising from the confluence of many different ice-streams, where 

 the veined structure is found in ice many miles distant from the 

 spot where it was deposited hundreds, it may be thousands, 



