- a Public Road under the Thames. 67 
by public advertisement, that the directors were desirous of re- 
ceiving designs for proceeding again in this work, and they offered 
a premium of £200 for the plan which should be adopted, and a 
further premium of £300 upon the execution of it. Since that 
time the project has lain dormant. Lately a pamphlet has ap- 
peared, entitled “ A New Plan of Tunnelling, calculated for open= 
ing a Road-way under the Thames, by M. T. Brunel, Esq., in 
order to the raising a capital of £ by transferable shares of 
£100}each,” for commencing again this project. Mr. Brunel 
describes his plan as follows: ‘* The character of the plan before 
us consists in the mode of effecting this excavation by removing 
no more earth than is to be replaced by the body of the tunnel, 
retaining thereby the surrounding ground in its natural state of 
density and solidity.” 
Mr. Brunel proposed that the excavation, 34 feet wide by 18 
feet high (external dimensions), consisting of 33 such drift-ways 
as that before mentioned, moving simultaneously, worked by 33 
men, at the rate forward of three feet per day, followed by a brick 
tunnel at the same pace, should pass in a stratum which he states, 
* has been found to resist infiltrations,” so that the crown of the 
tunnel will have a head of earth on it, from 12 to 17 feet in thick- 
ness, quite undisturbed, as he expects. 
' The method proposed by Mr. Dodd, at Gravesend, by Mr. Vazie, 
at Rotherhithe, and by Mr. Brunel, is by mining. Other methods 
may or have been proposed, such as to dredge out a channel in the 
bed of the river by machinery in vessels, and afterwards to sink 
therein caissons with brick or stone tunnels in them, to be after- 
wards secured together and perforated; or to sink large iron cy- 
linders or boxes, the size of the proposed tunnel, with moving, 
lapping, and closing joints, let down, one after another, on strong 
iron mooring chains, into the channel so dredged out; the junc- 
tions to be facilitated by means of the diving-bell: but these 
schemes are of a very adventurous character, and might be tried 
perhaps with propriety in the case of a small passage under a 
river, The apparent cheapness of such methods seems calculated 
F2 
