Mr. ^tiniiA 0)1 a New Plan ()/' Tunnelling. 139 



matliematician as M. Laplace. But what I have adcUiced are 

 not the only instances in which his theory and facts manifest 

 the clearest opposition. Many others could be easily advanced, 

 which, had this philoso})her attempted to extend his researches 

 beyond the three simple laws he has considered, could not 

 fail to have shown him th.e marked sterility and insufficiency 

 of his principles. For instance : had he tried to explain the 

 facts in tiie conducting powers of gases discovered by Leslie, 

 Dulong and Petit, Dav}', &c., or the well known laws of va- 

 pours discovered by Dalton and Gay-Lussac, he would have 

 found, besides the absurdities in capacity which I have men- 

 tioned, that his principles are not merely inadequate to explain, 

 but repugnant to most of thephsenomena; and are incapable 

 of even a semblance of probability, without adding to the hypo- 

 thetical assumptions already but too much outnumbering the 

 phaenomena expounded. 



Cranford, London, Aug. 19, 1823. J. LIerapath. 



XXIX. Description of a New Plan of Tunnelli7ig, calcu- 

 lated Jbr openiiig a Roachvay tmder the Thames.* Bi/ M. J. 

 BuuNEL, Esq. C.E. F.R.S. 



T^O discover convenient and efficacious means for opening a 

 -*- sjxicious subterraneous communication between the shores 

 of a great river, without occasioning any obstruction to the 

 navigation, has long been a desideratum of considerable im- 

 portance with the public, and in the estimation of scientific 

 engineers. The difficulties which have opposed themselves to 

 every attempt that has been hitherto made to execute a Tunnel 

 under die bed of a river, have been so many and so formidable 

 as to have prevented its successi'ul termination in those in- 

 stances where the attempts have been made. 



To propose therefore the formation of a Tunnel after the 

 abandonment of these several attempts, may appear somewhat 

 jnesumptuous: on incjuiring, however, into the causes of fiiilure, 

 it will be found that the chief tlilliculty to be overcome, lies in 

 the inefficiency of the means hitherto eniployed for forming 

 the excavation upon a large scale. 



In the case of the drift-way made under the Thames at 

 Rodieriiithe in IHiYJ, the water piesentcd no obstacle for 930 

 ieel; and when a great body of (|uicksand gave way and filled 

 the drift, tlie aiiners soon overcame this obstruction, and were 



• Proposals for tlic excciilion of tliis plan Itavc been lately issued, with 

 pxpianalory i'lates. iwo of wliich \vr arc enabled to give tlnougli tiie kind- 

 ncsb ol'tlic auiliur. (I'lates II. and HI.) 



S 2 ablo- 



