The New York herald., 1874-11-24

be continually exposed to collisions and might re.
qulre mafs OF material 20 secure II from such
be removed. But in 1853, as soon as sufncienS
funds were granted for large operations, the corer
rss a. Ss o!
/ sides the great extent OF the rock, there was no
danger 70 be apprehended from collisions.
THE NODE OF BLOWING UP
the reef at Hanetvs Point would generally be
this:-To perlorate from the inside each pier with
s9jicent number OF these being provided to COM
piete the destruction OF the pier when lully
same pier to be connected together, and fuse
composed OF quick explosive 10 connect the sys-
n
tion OF heat or the electric spark to lew centres
OF explosion would sufice TO propagate it through
the connecting fuse would advance more
rapidly than the demolition Of the rock
others confined In strong vessels might be
placed IN the inside close against the ROOF, and be
greater effect Tne piers might be blown down by
charges placed in contact with them; or 10 the
galleries large charges might be placed, suillcent
OF explosives would be required IN such process;
whereas the proximity Of the work to hahltailons
be used. but that II be so confined as to perform
local work only. water tamping by hoodlng the
ments OF rock. The principle OF water tamping
was, believe. drst used by Malllefert In surface
isSs ana s%oseauens years and ali engineers who
have been since engaged In the removal OF SUB.
marine rocks have used 1t.
cipaly Il not exclusively, In the demolition Of the
works at halett's Point, and they should be con-
AS it may require several weeks TO charge the sys.
tenn OF holes and their connections, II nttrO-gly.
part be USED In metalilc tubes, danger might re-
suit from c0rrosion or from coupling these t0-
gether. II nltro-glycertne be used in metallic
tubes it might be best to fiji these after they have
been set up and connected.
II the tubing be composed OF gutta percna or
rubber. Besides the advantages already gwen as
pertaining to the latter description OF tubing,
another that OF freedom from leakage would De
more readily secured, and this consideration Is .
matter OF first Importance when nitrO-glycerine
neuaa n nos so il gun cotton be- the sIplosye
Captain Wlliam Il Heuer, Corps OF Engneers'
49," mas az IL he
services have been faithfully and effectively
The operations OF this machine were condned
to Coenues Reef commencing work June Is, ana
ssang @ up on that Date Was Ss
haustion Of funds available Tor the work, and was
particularly unfortunate. as but little addltionale
cost was needed to bring the level OF the rock to
the depth required. and there was apparently
nothing further to be done than to remove broken
heap Of loose stone, is 2lh feet at mean low
water and the depth proposed is from "a
to s sds feet bods puras ns 10 ae 81
feet, were drilled The diameter of holes at the
top WAS generally AZ inches and ct bottom 81
inches. The amouat OF nitro-glycerine expended
was 1927 lbs., and this included likewise the
charges OF 80 surface blasts The amount OF
stone grappled and removed from the rect was
2,S05 cubic yards, and this does not include the
amount, which iS unknown, raked from the sur
face into the deeper water on the sides OF the reef
The operations OF the past season were under the
superint ntendence OF Mr.. j. Il. Striedlnger, civil
engineer, and were faithfully and sklllully con-
ducted. During the present season the machine
will De put to Work upon Shelldrake and Ways
Reef, In He'll Gate.
THE ESTIMATES.
The estimate OF January u, 1857, for the removal
of certain oDstructiOns IN He'll Gate HalletL's
Point, the Middle Reef ana smaller ROCKS, as Pot
Rock, Frying Pan, Ways Reef and Shelldrake,
amounted TO S8.892,645. The mode Of operation
drilling into the surface OF the rocks, blasting
and removing the debris and the estimate per
cubic yard was $4S 28-a rate which Is thought to
be correct for the operations In question. At
later date January g. 1870 new estimate, based
upon the process OF tunnelling the larger reefs,
as Haett's Point and the Middle Reef, and remov-
ing the smaller reefs by drilling from the surface OF
the water was made, and the average rate per cubic
yard fixed at SIS as q minimum and $50 Tor the
maximum. The quantities IN the Middle Reef ana
veys, though only approximate, must be retained.
advanced to furnish 8 more correct volume.
Reefs He'll Gate 234 cubic YARDS $40. $40
Diamond and Coentes reefs letter Of March 2, ..