Proceedings of Learned Societies. 395 



not a new one : it has long since been proposed to utilise the force 

 generated by descent down one incline for ascent up the next : so 

 that some of the motive power required for propulsion of a train, 

 should be obtained from gravity. An ingenious means of storing up 

 the force of gravity so as to prevent the great variations of velocity 

 which constitute one of the most serious objections to an undulating 

 railway, is being experimented upon in Paris. The engine by 

 which the motive power used for propulsion of the train is furnished, 

 is provided with two heavy fly-wheels, capable of being made to 

 work with or in opposition to the driving wheels. During descent, 

 these fly-wheels, being made to revolve by the driving wheels, cause 

 great retardation, and at the same time store up the power they 

 have thus absorbed. Continuing to revolve with great velocity 

 when it is necessary to ascend, they are so connected with the 

 driving wheels that they cause them to revolve. The train is thus 

 propelled, and at a practically uniform velocity, since from the large 

 amount of matter the fly-wheels contain, they can lose a considerable 

 amount of motion, without their velocity being greatly affected. 

 Some motive power, independent of that obtained from gravity, would, 

 of course, be required to supply the loss of that destroyed by friction, 

 and ihe resistance of the air; but the amount must be incon- 

 siderable. 



PROCEEDINGS OF LEARNED SOCIETIES. 



GEOLOGICAL SOCIETY.— Nov. 6. 

 Warrington Smyth, Esq., President, in the chair. 

 A. Tylor, Esq., P.L.S., etc., read a paper on the Amiens Gravel. 



The author referred first to the prevalent views respecting the 

 gravels of the Valley of the Somme, namely, (1) That there are two 

 deposits of distinct age — the upper and the lower valley gravels ; 

 (2) That the former of these is the older ; (3) That the Valley of 

 the Somme has been excavated to the depth of forty or fifty feet 

 since its deposition ; (4) That both gravels contain bones of extinct, 

 animals, and implements of human manufacture, the lower gravels, 

 however, containing the greater number of species of Mollusca, and 

 the upper the greater number of flint implements ; and (5) That 

 the height (seventy feet) of the gravels of St. Acheul above the 

 present level of the Somme is much beyond the limit of floods, and 

 that, therefore, they could only have been deposited before the 

 river channel was cut down to its present level. He then pointed 

 out that the general effect of these views is to refer back the remains 

 of man found at St. Acheul to an indefinite date separated from 

 the historical period by an interval during which the valley was 

 excavated. 



In former papers Mr. Tylor stated his belief that the upper 

 and lower valley- gravels of the Somme are continuous, and of 



