1882. 157 Trans. N. V. Ac. Scz. 
nineteen feet in width by twenty-four in height. The whole would be 
lined with brick ; but this brick wall and arch would not be quite in 
contact with the chalk excavation, but a space was to be left between, 
to allow any percolating water to pass down without entering the tun- 
nel-way and escape beneath its floor. This escape would be secured 
by the slope of the tunnel, which is to be highest at the middle and de- 
scending somewhat toward each end, where large reservoirs will be 
excavated for any accumulating water, which will thence be removed 
by powerful steam pumps, raising it through shafts to the surface. The 
important matter of ventilation is to be provided for by engines at 
either extremity, so working as to insure a steady and powerful current 
of air through the entire tunnel, one pumping air, and the other ex- 
hausting it. 
The machinery employed in the work of excavation was also referred 
to and illustrated ; but it is peculiar and complicated, and cannot be 
wel] described, save at length and with figures. In working through 
the comparatively soft chalk, the process is strictly one of cutting ; and 
a very ingenious and beautiful machine is employed, wherein a series 
of blades, like knives set upon revolving wheels, is made to cut the 
chalk at the extremity of the boring. The machine itself is also ad- 
vanced on wheels, as it works onward the heading from day to day. 
Thirty-six feet is about the daily rate of progress; and it is computed 
that the whole will be finished in five or six years. 
Estimates were then given of the profits which it is expected will be 
realized, if the work is successfully completed. The amount of funds 
requisite to do this will be forty to fifty millions of dollars; say, ten mil- 
lions of pounds sterling. Three-fourths of the present passenger traf- 
fic should, it is altogether probable, prefer the tunnel to the channel 
voyage ; and, considering the advantage in freight-transit of not “‘ break- 
ing bulk” for shipment, the receipts may be estimated roughly as fol» 
lows : 
I ASSEMEERLEAVEM soho alniop os c.ct oe eee wise cam eee ee £850,000 
peiomiemys eye tee sill. Ay eRe see, 6300;000 
VME RVICOn MCLG MIRNA GER: fais 2. ors nts cigrh ajehsh Iho ie o's o's 50,000 
ott terse seen coe es oe: ce evel os ae ies atsra Sie £1,200,000 
Deducting from this, say, forty per cent. for expenses (£ 480,000), or 
somewhat less, there will remain a profit of £720,000, or more, which 
would yield from seven to seven and a half per cent. yearly on the cap- 
ital of £10,000,000. If this capital seems large, it is not so in compar- 
ison w:th the sum already invested in the English railways, which 
amounts to about £700,000,000. 
For his own part, the lecturer was fully convinced alike of the need, 
