Year: 1868

twentyfour feet but as this only done because In
order to reach the latter may be necessary to go 40
mates Us mere given, Omitting the cents:-
fotai I lor Improvement by first PROJECT, Six
SECOND project ten yeais operations. Add


.o,anw,ui 70 an,2unt oI nrst project the cost for


and Chicken, and the Grdiron, increased


by extra repairs and replacement of ma


vices for ten instead OF six Years and


dimlnisned Dy cost Of removing Negro


Head and improving the middle channel


and for cut stone wall designed for the


Gridiron, viz amount to be added -. 2s49 45y
Total for Improvement by second project S. 2l6 SO
Third project, four years. operations. Omit


ting all Improvements OF the middle


channel with corresponding dmunitiOL


OF cost and decreased wear and tear OF


machinery and OF contingent services.


deduct from cost Of first project. 2,7ooses


Total for improvement by third project. s. eo4 ssS


The report likewise submits the following table:-
Estimated cost OF first project $6,S65,s
Amount saved BY using ,ach driIi sn BORING m INTO


including cost Of one drilling platform,


which might then be dispensed with.... 49,775
Amount saved by using nitro-g o-glycerine in


stead Of gunpOwder, when its explosive


force Is estimated at ten times that oi the
Or s.io per cent.


Amount saved by using nitro-glycerlne In


stead Of gunpowder when lts explosive


force is estimated at thirteen times that OF


the latter ........................... l3l 910
Or less than 2H per cent


The report thus proceeds:-The small proportion
which an improved process of drilling rock or the
use OF O more powerful explosive agent Will save In
the total cost may surprise many; but the cause ts
evident-viz the small proportion Of the cost OF ths
whole blasting process to that OF the 0ther Items OF
the project. The table likewise shows that as ques-
ton OF cost this Improvement is independent or any
particular form OF Improved machinery FOR druhn4
special explosive agent, leaving to the government
full liberty OF choice in these respects For the sake
of the men employed upon such works no compound
should be used which Is likely to explode sp0n,
taneOusly or from causes beyond the control OF
ordinary carefulneSs. Certain conclusions may be
cOncisely stated. Any reasonable hope OF e1ectina
this improvement depends upon the rejection OF
misty and fanciful schemes which cannot be brought
within the rules of ordinary calculation This report
has attempted one method Of solution, and 1t Ia
hoped many better may be found. 1t was necessary
in framing the estimate to make just and liberal al
lowances and to provide for contingencies and acct
dents attending operations not only difficult In them
selves but also little assisted by data from any source
On the other hand there no doubt thata serious ana
well considered attempt to push the work will be the
to this end which, with the experience gained from
day to day. will not only expedite progress but also
materially diminish the COST especially in the large
item of removing the rock. The precise depth to be
attained viii be dependent not only upon the present
but upon the future draught OF vessels On this
point must be considered that this Is the only chan
mel leading to New York where additional depths
can be gained and liberal standard in fixing this
would be best, since II error be committed in the oP
posite extreme >he cost Of remedy would be only u
not quite equal that OF the first operation.