Fbbruaey 7, 1902.] 



SCIENCE. 



235 



subaerial erosion only, and regards this as a 

 natural consequence of the massiveness and 

 relative rigidity of the ice streams. The val- 

 leys are comparatively straight, with broad 

 floors and rather smooth and steep sides, head- 

 ing in amphitheaters or corries that seem un- 

 duly large for their drainage areas. The 

 valley floors frequently descend by abrupt 

 slopes to lower and lower levels. Rock basins, 

 excavated in the valley floors, and holding 

 lakes, are justly regarded as subordinate and 

 incidental to the general scouring of the 

 shallower and narrower preglacial valleys to 

 their present trough-like form. Short side 

 glens open characteristically on the walls of 

 the larger valleys to which they are tributary. 

 The divides between the uppermost corries of 

 the main valleys are sharply serrate, in con- 

 sequence of the retrogressive erosion of the 

 glaciers that headed in the corries, as has 

 been pointed out by Eichter for the Alps, and 

 by Matthes for the Big Horn range of the 

 Rocky mountains. 



The comparison instituted by Harker be- 

 tween rivers and glaciers is not altogether 

 satisfactory inasmuch as it fails to point 

 out certain similarities between the two. It is 

 stated that, 'the bed of a river which has at- 

 tained a mature state maintains a steady 

 gradient so long as the volume of water is un- 

 changed ' ; but it is the surface, not the bed, of 

 the river that should be thus described. The bed 

 of a mature river, such as the Mississippi, has 

 numerous hollows, whose dimensions are to 

 those of the river in about the same propor- 

 tion as the dimensions of rock basins are to 

 those of the glaciers that scoured them out. 

 When a mature river crosses a reef of re- 

 sistant rocks, it habitually sweeps out a 

 shallow basin-like depression in the weaker 

 rocks next up stream; while another basin 

 may be eroded by the plunge of the waters 

 down stream from the reef. Rivers whose vol- 

 ume is greatly reduced in the dry season ex- 

 hibit the hollows in their bed as a series of 

 pools strung together by the diminished 

 stream. It therefore seems wrong to say that 

 'ice erosion does not, like water erosion, work 

 constantly towards the establishment of an 

 even gradient along a valley.' Both tend to 



establish even gradients in their surface; both 

 produce inequalities in theirbeds;the inequali- 

 ties of a river bed receive little attention ; they 

 are comparatively small and are usually out 

 of sight; the inequalities in the beds of ex- 

 isting glaciers are even less open to observa- 

 tion, although it can hardly be doubted that 

 they exist.. The inequalities in the beds of ex- 

 tinct glaciers are often so large and so plainly 

 visible that their analogy with the hollows in 

 river beds is too commonly ovez-looked. 



THE SEVERN" BORE. 



A SERIES of views of the Severn bore taken 

 with a bioscope camera by Vaughan Cornish 

 was thrown on the screen at a meeting of the 

 Royal Geographical Society of London in 

 November last, the first cinematographic illus- 

 tration of this tidal phenomenon. Four of 

 the views are reproduced in the Geographical 

 Journal for January, 1902, and show the ap- 

 proach and passage of the bore with some dis- 

 tinctness. Cornish proposes to make similar 

 studies of other tidal rivers. His well-known 

 studies of rippled sands, under waves, tides and 

 winds have been published in recent years. 

 W. M. Davis. 



RETIREMENT OF MONSIEUR EATON. 



The report of the proceedings at a meeting 

 of the faculty, alumni and friends of M. Haton 

 de la Goupilliere on the occasion of his retire- 

 ment from the directorship of I'Ecole nationale 

 superieure des Mines, accepting Vice-Presi- 

 dency of the Conseil general des Mines is just 

 distributed. This ceremony took place June 8, 

 1901, in the great auditorium of the Societe 

 d'Encouragement. The list of contributors 

 numbered 580 and the farewell offerings were 

 numerous and various, including a bust of M. 

 Haton and bronzes by Dubois and others. 

 The bust is reported to have proved a very ac- 

 curate likeness of its distinguished original. 

 The addresses were made by M. Carnot, Di- 

 rector of the Ecole des Mines, and M. Lemon- 

 nier, president of the Association. 



M. Haton was 'Eleve ingenieur' in 1853, 

 when about 20 years of age, was made pro- 

 fessor in the preparatory course immediately 

 on graduation as Ingenieur, taught general 



