1842. 



THE CIVIL ENGINEER AND ARCHITECTS JOURNAL. 



347 



sisted that the engineer should, in such instances, and for the cross railways, 

 which he yet hoped might be introduced, make the gradients and carves 

 ranch less theoretically perfect ; and that the amount of expenditure, beyond 

 the above stated necessary one of £10,000. per mile, should be reduced to 

 the very minimum ; and lie considered that henceforth an average ot £15,000. 

 or £16.000. per mile, and a maximum of £20.000.. or, in very extraordinary 

 cases, indeed, of £25,000., should be looked to for the construction of double 

 lines of railway in any country, but that in most cases, of light traffic, and 

 consequent adaptation of gradients, for single lines, a sum of from £7000. to 

 £12,000. per mile would be the limit of total expenditure. Mr. Vignoles 

 concluded by observing, that the preceding abstracts were deduced from very 

 detailed accounts, which had been arranged on a uniform system, and kept 

 from the very commencement of each undertaking, so as to be available, at 

 any time during the progress of the works, to show the exact state of the 

 expenditure ; and had been finally worked out to the nearest thousand 



pounds, as above. And the Professor expressed his great hope and expecta- 

 tion that this example would be followed, and that similar accounts would 

 shortly be forthcoming, of the corresponding items of cost on all the prin- 

 cipal railways in this and in other countries, more especially where com- 

 plaints of improper excess of expenditure over estimates (well or ill-founded) 

 had been charged, for the publication of such accounts— and the more in 

 detail the belter— would be the most complete defence of the directors, and 

 the most satisfactory explanation from the engineer, and alike valuable, as 

 statistical information, to the country — as salutary guidance to the capitalist 

 and speculator— and as valuable information and naming to the old as wel 

 as to the young practitioner. 



The preceding is a very brief outline of this interesting lecture, and the 

 following, we believe, is a correct abstract of the cost of the two railways 

 quoted by Mr. Vignoles. 



Comparatiee Abstract of the Cost of two Principal Lines of Railway, under the general heads of Expenditure, as deduced from the very latest accounts 



of Actual Expenditure, brought out to the nearest ro»nd numbers : 



PROCEEDINGS OF SCIENTIFIC SOCIETIES. 



ACADEMY OF SCIENCES. 



June 20. — A paper by M. Vicat was read, " On the nature of Poxtzzo- 

 lanes." — M. Vicat, having discovered the nature of the substance, has been 

 able to compose a substitute with pure clay, calcined whilst exposed to a 

 dead heat, so as to get rid of eight or nine-tenths of the water combined 

 with it. The best clay for the purpose, says this gentleman, is pipe-clay ; 

 and in proportion with the admixture of iron, manganese, carbonate of lime 

 or sand, is the defect of quahty. 



M. Degousue gave an account of some recent results in the making of 

 Artesian wells. He states that he has bored for water in the plateau which 

 extends from Lagny to the forest of Arminvilliers, at the height of 110 

 metres above the Marne. In one spot an abundant supply of water rushed 

 out, although he had gone to a depth of only nine metres. With M. De- 

 gousee's report he forwarded to the Academy a letter which he had received 

 from Aime-Bey, the director of the mines of Egypt, who announces his in- 

 tention of re-opening some of the bored wells of the ancients, at the foot of 

 the Libyan chain, and requests that the necessary instruments may be sent 

 out to him for that purpose. 



June 27. — A paper on the effect of oil in calming the waves of the sea. 

 By M. Van Beck. — M. Van Beck thinks, with Franklin, that the pheno- 

 menon may be explained by admitting that there exists between air and 

 water a certain natural affinity or adhesion. Water, he says, takes in with 

 avidity the air with which it comes in contact, so that it is with diihculty 

 expelled. It results that, whilst a current of air passes over the surface of 

 the water, the air attaches itself to the liquid, and creates small waves, 

 which, as the wind increases, become large and dangerous. As soon as these 

 waves are covered with a membrane of oil, the adiiesion of the air upon the 

 water ceases to exist, and the surface is no longer disturbed. 



A communication was read from M. Combes, on the thermal springs of 

 Mamant-Escoution, on the Banks of the Raz-el-Akbar, in Algeria, about 



thirty leagues from Bona. The waters of these springs, which rise in the 

 midst of a plaia from Utile conical domes formed by themselves, are sulphu- 

 reous, and of the high temperature of 80° of Reaumur. 



July 4. — A paper was read " On the Geological State of the southern part 

 of Brazil, and on the Heavings-up of the Earth, which have at imrious periods 

 changed the appearance of the country," by JI. Pissis. The ground examined 

 is situated between the 12th and 27th degrees of central latitude, and com- 

 prehends the space between Parana, San Francisco, and the sea. Three 

 periods of rising or heaving up are perceptible in Brazil, the last belonging 

 to the end of the tertiary period. The immersion of certain strata placed at 

 the bottom of the province of Bahia, and a sUght elevation of the table lands, 

 found between the sea and San Francisco, have been the results of it. 



" On the action exercised on the surface of various Liquids, hy the influence 

 of the Vapour of certain Substances, and by their immediate contact." By 

 M. Dutrochet. Light bodies placed on the surface of the water are repelled 

 to a certain distance by the vapour of camphor, of ether, or even of alcohol,' 

 and the essential oils. M. Dutrochet's experiments op|)Ose the opinion 

 hitherto received, that this phenomenon is due to the impulsion which re- 

 sults from the rapid expansion of the vapour, which, striking on those light 

 bodies, produces the removal of all the liquids subjected to the experiments. 

 Ether is the one which produces the most vigorous movement of light bodies 

 placed on water, mercury, and several acids and alkalies, but the movement 

 is not always a repulsion, and is subject to great variation. Thus the vapour 

 of ether attracts flour of sulphur placed on the surface of sulphuric acid, and 

 produces a repulsion on the surface of nitric acid. If water be added to 

 these acids, the movement is weakened in proportion as the quantity of 

 water is increased. M. Dutrochet attributes tiiese different movements to a 

 modification of capillary attraction. He observes that, in reahty, there is 

 neither attraction nor repulsion in the floating bodies, that tlieir displacement 

 impedes the current, of which the surface of the liquid is the seat, and which 

 has its origin in the heaving up or depression below the liquid, which may be 

 reduced to steam. 



July 18. — .V paper was read by M. Rameaux, of Strasburg, on the vital 

 heat of plants. M. Rameaux has ascertained that the heat varies materially, 



3 C 2 



