ii8 Mr. H. H. HowoRTH on 



there will be a natural tendency to molecular dislocation in a 

 direction sloping towards the middle of the glacier. As we 

 near the centre of the glacier, the friction due to the bed of the 

 glacier will more and more modify the effects of that due to 

 its walls, until the lamination will take place entirely in the 

 vertical plain, causing the spoon-shaped arrangement of the 

 surfaces of dislocation as observed. He then goes on to show 

 how the phenomenon of the frontal dip is explainable by 

 the same notion that the glacier really moves as viscous 

 bodies move (Article, Glacier, in E.B., for 1855). 



He urges (i) that it accords with the view of the origin of 

 the bands, that the glacier actually does move fastest in the 

 centre, and that the loop of the curves described coincides 

 by observation with the line of swiftest motion. (2) That 

 the bands are least distinct near the centre, for there the 

 difference of velocity of two adjacent strips parallel to the 

 length of the glacier is nearly nothing, but near the sides 

 where the retardation is greatest, it is a maximum. (3) The 

 less elongated form of the loops in the upper part of the 

 glacier corresponds with the observed fact, that the differ- 

 ence in velocity between the centre and sides is greatest 

 near the lower end of the glacier, and that the velocity is 

 most uniform in the upper part. (4) In the highest parts 

 of such glaciers, as the curves become less bent, the structure 

 also vanishes. (5) In wide glaciers, where the velocity is 

 nearly uniform across their breadth, no vertical structure 

 is developed, while the friction of the base developes an 

 apparent stratification parallel to the slope down which 

 they fall. (6) It also follows that the frontal dip of the 

 structural planes of all glaciers diminishes towards their 

 lower extremity. (7) When two glaciers meet, the structure 

 immediately becomes more developed ; this is due to the 

 increased velocity as well as friction of each, due to lateral 

 compression. (8) The veined structure invariably tends to 

 disappear when a glacier becomes so crevassed as to lose 



