PEOFESSOR TYNDALL ON THE VEINED STEDCTDEE OF GLACIEES. 307 
fied by the squeezing at the base of the fall ; and it is the undulations which produce 
the bands. Thus the latter connect themselves with the transverse fracture of the 
glacier as it crosses the brow of the fall. 
In the figm’e I have given the general aspect of the bands, but not their number. 
Thirteen of them exist on the Glacier du Geant. I may add that the bearing I have 
assigned to this glacier differs from that assigned to it on the map which accompanies 
Professor Foebes’s ‘ Travels on the Alps,’ and which I had with me at the Montanvert. 
The reason is, that on the map the true north is drawn on the wrong side of the mag- 
netic north, thus making the “Declination” easterly instead of westerly. I have since 
learned that this error is corrected m the smaller work of Professor Foebes. 
It has been affirmed that the dirt-bands cross some of the medial moraines of the Mer 
de Glace, and they are thus drawn upon the map of Professor Foebes. Were this 
correct, my explanation would be untenable ; but the fact is, that the bands are confined 
to the Glacier du Geant from beginning to end. 
Eoyal Institution, February 1859. 
