1823.] 
takes out one of the small boards at a 
time, cuts the grownd to the depth of a 
few inches, and replaces the board 
before he proceed to the next. When 
he has thus gained from tbree to six 
inches over the whole surface, (an 
operation which it is cxpected may be 
made in all the cells nearly in the 
same time,) the frames are moved for- 
ward, and so much of the brick-work 
added to the body of the tunnel. Thus 
intrenched and secure, thirty-three 
men may be made to carry on an ex- 
cavation which is 630 feet superficial 
area, in regular order and uniform 
quantities, with as much facility and 
safety as if one drift only of nineteen 
feet square were to be opened by one 
man. 
The drift carried under the Thames 
in 1809, which was about the size of 
these cells, and was excavated like- 
wise by only one man, proceeded at 
the rate of from four to ten feet per 
day. In the plan now proposed, it is 
not intended that the progress should 
exceed three feet per day, because the 
work should proceed with mechanical 
uniformity in all the points together. 
With regard to the line of opera- 
tion, if we examine the nature of the 
ground we have to go through, we ob- 
serve under the third stratum, which 
has been found to resist infiltrations, 
that the substrata to the depth of 
eighty-six feet are of a nature that 
present no obstacle to the progress of 
a tunnel; we are informed that no 
water was met there. It is therefore 
through these substrata that it is pro- 
posed to penetrate, and to carry the 
line that is 10 cross the. decp and 
navigable part of the river, leaving 
over the crown of the tunnel a head of 
earth of from twelve to seventeen feet 
in thickness quite undisturbed. 
Admitting that in descending to, or 
in ascending from that line, we should 
come to a body of quicksand, such as 
that which was found within about 200 
feet. from the shore, it is then we 
should find in the combinations of the 
framing, before described, the means 
that are necessary for effecting, upon 
a large scale, what is practised on a 
very small one by miners when they 
meet with similar obstacles. Indeed, 
were it not for the means of security 
that are resorted to on many occasions, 
mines would inevitably be over- 
whelmed and lost. 
Notwithstanding we may encounter 
obstacles that may retard the daily 
A New Plan of Tunnelling. 
All 
progress, it is with satisfaction we 
contemplate that every step we take 
tends to the performance and ultimate 
completion of the object; and, if we 
consider that the body of the tunnel 
must exceed the length of Waterloo 
Bridge, it must be admitted that, if, 
instead of two years, three were ne- 
cessary to. complete the undertaking, 
it would still prove to be the most eco- 
nomical plan practicable for opening 
a-land-communication across a navies 
gable river. 
No notice is taken here of the mode 
of constructing the descents or ap- 
proaches into the tunnel; because 
whatever form or direction it may be 
found necessary to adopt, it is obvious 
that no difficulties oppose themselves 
to the accomplishment of that part of 
the work, the experse of which is 
however taken into account in the 
estimate. 
Nature of the Ground under the Bed of the 
River at Rotherhithe, at a short distance 
below the place now proposed for opening 4 
Roadway. 
Feet, Inchese 
1. Stratum consisting ef brown 
clay oeeee 
2. Loose gravel with a_ large 
quantity of water-++++++--+26. 
S. Blne alluvial earth inclining 
epee ncceseeseses 9 0 
to clay s+eeeeressesecceees $3 0 
A. Loamsscevcsecsseceoeeres J 1 
5. Blue allnvial earth inclining 
to clay mixed with shells--++ 3 9 
6. Calcareous rock, in which 
are imbedded gravel stones, 
and so hard as to resist the ‘ 
pick-axe, and to be broken 
only by wedgesssseees+e+++ 7 6 
7. Light-coloured muddy shale, 
in which are imbedded pyrites 
and calcareous stones e+e. 4 6 
8. Green sand, with gravel and 
a little water -+e+--+-eeeers O 6 
9, Green sand -+--eeesersees 8 | 4 
68 4 
——— 
For the Monthly Magazine. 
EXPOSURE of the FRAUDULENT PRAC- 
TICES of GRANTORS Of ANNUITIES. 
HEN a young nobleman or gen- 
tleman finds himself in want of 
the necessary means of happiness, and 
his father refuses him a supply, he is 
naturally led to communicate his dole- 
ful case to his friends; and some one 
of them soon tells him, not to make 
himself uneasy, for he may be accom- 
modated in a short time, and with very . 
little trouble: and he is then informed 
of 
