Feb. 4, 1886] 



NATURE 



;i9 



On the east side of the valley, perhaps 150 feet above the level 

 of the road at Lie Station, I could distinctly trace this terrace 

 by its hummocks of water-laid sand, and the farmhouses perched 

 on its favourable points. A long series of hamlets on the road 

 to Molde is placed upon it. As an object in physical geography, 

 in its form, its imiform level on both sides of the vale, and its 

 relation to the lakes at the summit-level, this terrace precisely 

 resembles the lowest of the Glenroy terraces as it approaches 

 Loch Laggan. It must, however, be more than twice the level 

 above the sea" (p. 105). Chambers, of course, viewed it as an 

 ancient sea-margin. 



The same long terrace was also seen by my colleague, Mr. J. R. 

 Dakyns, in 1S72, and described (without reference to Chambers) 

 in the Geological Magazine, 1S77, p. 74. " If the terrace is on 

 a level," he says, "with the watershed, and there is certainly 

 no great difference between them, one is irresistibly led to think 

 of the similar case of the parallel roads of Glenroy, and ... of 

 a gigantic Marjelen See dammed back by ice till it overflowed 

 the summit of the pass at Molmen. It is significant that I could 

 see no trace of terrace or water-mark on the Romsdal side of 

 the pass. There is in the same district a second horizontal 

 mark on the solid rock, several hundred feet higher than the 2000- 

 feet one. This, too, seems to correspond with sand-terraces in the 

 recesses of the high glens. . . . Here again it is striking that 

 the water-mark should seem to correspond with the level of a 

 watershed." 



I myself saw Chambers's striking terrace in 1873. But I have 

 nothing to add to the observations above quoted, and I make no 

 claim whatever to have my name connected with them. But I may 

 remark the fact that the little deltas or alluvial cones of the streams, 

 where these cross the terraces, so conspicuously bear reference 

 to the surface of the vanished sheet of water in which they were 

 formed, .as to remind one how greatly similar evidence was relied 

 on by Darwin as demonstrating the aqueous origin of the roads 

 of Glenroy. Mr. Hansen's discovery of parallel roads at the 

 head of the Glommen and in Jemtland is very interesting, and 

 I hope he will find time to study and map them in detail. 



Hugh Miller 

 51, Lauriston Place, Edinburgh, January 24 



Meteorological Phenomena 



On January 4 last, while watching a very bright rainbow with 

 a good secondary from Hoylake racecourse, I observed between 

 the two bows a third, fainter than either, touching the primary 

 at the base and extending upwards in such a way that probably, 

 had it all been visible, it would have touched the secondary at 

 the vertex. It was not all visible because of a break in the 

 clouds. Its colours were in the same order as those of the 

 primary, red outside. This third bow was only visible at one 

 side ; but a gentleman who observed it stated that he had seen it 

 before, and symmetrical on both sides, though not extending to 

 the vertex. 



Another phenomenon I have observed here some time ago. A 

 fall of hail lasting a few minutes occurred, the hailstones being 

 exact cubes, of size about 7 mm. and of consistency like lumps 

 of salt. John C. Willis 



University College, Liverpool, February i 



M. BARRA DE SAINT-VENANT 



" Al /■£ have now to consider the earlier work of the 

 • • greatest of living elasticians." Within a fort- 

 night after these words were sent to the press, on 

 January 6, M. de Sailit-Venant died at Vendome. The 

 news of his death will have caused a deep feeling of 

 regret among English mathematicians and physicists, 

 to whom his researches are so well known that they have 

 attained in their own field a classical value. We purpose 

 in this notice to give some brief account of this fore- 

 most representative of latter-day French mathematical 

 physicists. 



Saint-Venant stood out for the younger mathemati- 

 cians of the English school, as the link between the 

 past and the present. Intimately related to the great 

 period of French mathematical physics, he had con- 

 tinued to produce down to our own day, and we felt 

 him to be as real a personality as Helniholtz or Thom- 



son. A younger member of the school of Poisson, Navier, 

 and Cauchy, he had yet lived to "edit" Clebsch. Deputy 

 for Coriolis at the Ecole des Fonts et Chaussees in 1S37, 

 Saint-Venant early received public recognition for his 

 work from Poncelet in his lectures at the Sorbonne in 

 1840 ; within the next few years he corrected Cauchy 's 

 theory of torsion, and saw his correction accepted by the 

 author of the " Exercices des mathematiques." More than 

 forty years afterwards he " edits " what will long remain 

 the standard treatise on elasticity — the annotated French 

 translation of Clebsch. Thus his work is spread without 

 a break across the middle fifty years of our century ; he 

 took up elasticity where Poisson had left it — a mathemati- 

 cal theory ; he leaves it one of the most powerful branches 

 of mathematics applied to physics and practical engineer- 

 ing ; not a small amount of this transformation is due 

 directly to his researches, or indirectly to his influence. 



Turning to the personal character of the man, we find 

 in him the essential characteristics of the scholar and 

 the student, the truest modesty, the complete absence of 

 self, the single-minded devotion to his study. Saint- 

 Venant, whose researches on elasticity undoubtedly far sur- 

 pass those of Navier and Clebsch, is yet content to appear 

 as their editor. But what an editing it is ! The original 

 text is hidden, disappears, almost as completely as Peter 

 the Lombard's " Sententia " in a mediaeval commentarj'. 

 It is Saint- Venant's notes, appendices, and corrections, 

 which form the value of these works, which make the third 

 edition of Navier's "Leijons" the standard treatise on 

 the strength of materials, and the French translation of 

 Clebsch the foremost Avork on mathematical elasticity. 

 Nay, he even praises Clebsch for inventing a term in 

 1862, which he himself had first proposed in the privately 

 distributed lithographed sheets of 1837 ! Ever ready 

 with advice and assistance, perfectly free from jealousy, 

 Saint-Venant was a typical scholar. We had occasion, 

 scarcely six months ago, to apply to him for assistance 

 with regard to some of his earlier work. Within a few 

 days we received a packej containing twenty-three of his 

 memoirs, all carefully corrected, and many annotated. 

 Ke expressed a lively interest in the progress of the 

 " History of the Mathematical Theories of Elasticity," 

 lending the editor of that work several French litho- 

 graphed courses which were otherwise inaccessible, and- 

 accompanying them by letters which amounted almost to 

 a dissertation on the history of elasticity. 



" Je desire, bien cher monsieur, que ces quelques 

 renseignements et documents puissent servir k Futile 

 travail historique que vous avez entrepris, et dont 

 j'apprendrai avec plaisir la publication ainsi que le nom 

 de I'dditeur. J'en verrais meme avec plaisir les ^preuves." 

 Shortly before Christmas we received from Saint- 

 Venant corrections for the first three sheets of Dr. Tod- 

 hunter's ninth chapter, which is devoted to Saint- Venant's 

 earlier work. On January 3 we sent him the remaining 

 proofs of that chapter ; a week afterwards we had to 

 mourn the loss of one whose personal kindness had 

 served to intensify the respect raised by his transcendent 

 mathematical ability. 



If we examine the leading characteristics of Saint- 

 Venant's scientific w-ork we find them marked by an 

 essentially practical character. We find subtlety of 

 analysis combined always with practical physical con- 

 ceptions. The problems he attacks are those which are 

 physically possible, or of which the solution is an im- 

 mediate practical need. He smiles good-naturedly over 

 Lame's attempts to solve the terrible problem of an 

 elastic solid in the form of a right-six-face, whose surface 

 is subjected to any system of load. The solution would 

 be a triumph of analysis, but its physical and practical 

 value would in all probability be 7ii!. He chooses instead 

 a real beam, and he obtains a solution which, if it be but 

 approximate, is at least an approximation to reahty, and 

 will serve all practical purposes. Saint-Venant never 



