470 



HELL-GATE, IMPROVEMENTS AT. 



The chief articles reported during 1884 were 

 coffee, 31,560 tons ; cocoa, 691 tons ; cotton, 

 750 tons; logwood, 119,098 tons; sugar, 277 

 tons ; wax, 4 tons ; hides, 173 tons ; agave- 

 fiber, 1 ton; lignum- vitse, 217 tons; lignum- 

 vita3 gum, 14 tons ; orange-peel, 181 tons ; hon- 

 ey, 146,785 litres; and mahogany, 2,896,841 su- 

 perficial decimetres. 



The foreign trade in the same year was dis- 

 tributed as follows: Imports from the United 

 States, 52 per cent. : France, 21 ; Germany, 9 ; 

 England, 15; other countries, 3. Exports to 

 France, 65 per cent. ; United States, 14 ; Ger- 

 many, 9 ; England, 5 ; Belgium, 3, and other 

 countries, 4. 



HELL-GATE, IMPROVEMENTS AT. East river 

 forms a large portion of the water-front of New 

 York and Brooklyn, and is the most impor- 

 tant avenue of coastwise trade in the United 

 States. Its channel is scoured by strong tides, 

 which keep it permanently free from shoals 

 of sand and mud. Since the partial removal 

 of the obstructions in Hell-Gate, a heavy for- 

 eign trade has taken this route, notably the 

 petroleum-traffic, and, with the completion of 

 the improvements, the East river will afford 

 a convenient access for transatlantic steamers. 

 Its value will be still further enhanced by the 

 opening of Harlem river to the Hudson, prepa- 

 rations for which are now in progress. The 

 unobstructed navigation of East river would 

 also have an important bearing on the question 

 of national defense in case of war. It would 

 double the difficulty of blockading the port of 

 New York, and open Long Island Sound to our 

 larger war-vessels. The obstructions were all 

 within a short distance of one another, in the 

 strait called Hell- Gate, and were occasioned 

 by numerous reefs encroaching on the channel, 

 and the violent currents to which they gave 

 rise, making navigation extremely hazardous. 



Early Work. A process of surface-blasting 

 was first applied by M. Maillefert in 1851. His 



DRILLING-SCOW DECK PLAN. 



method consisted simply in placing upon the 

 rock a charge of gunpowder, usually of 125 

 pounds, in a tin canister, and exploding it by 

 the voltaic current. The weight of the water 

 resting upon the charge increased the effect. 

 No means were provided for removing the 



broken rock except by breaking it up by sac 

 cessive explosions till it was fine enough to b< 

 carried away by the currents. M. Maillefert', 

 operations resulted, by the use of 620 charge 

 containing 74,192 pounds of powder, at a cos 

 of $13,861, in removing from the rocks t< 

 which they were applied the projecting promi 

 nences of small area, but were of little effec 

 when, after reaching the main rock, a consid 

 erable extent of surface had to be dealt with 

 The depth of the water was increased, on Po 

 Kock, from 8 to 18'3 feet; on Frying-Pan 

 from 9 to 16 feet; on Way's Reef, from 5 t< 

 14 feet; and on Shell Drake, from 8 to II 

 feet. Bald-Headed Billy and Hoyfs Rock 

 were blown into deep water. The depth 01 

 Diamond Reef was but slightly if at all affect 

 ed, and no effect was produced on Hallet' 

 Point Reef. In 1852 Congress appropriate! 

 $20,000 for the removal of obstructions, an< 

 Major Eraser, by Maillefert's method, increase! 

 the depth over Pot Rock to 20-6 feet. In 185i 

 an advisory council to a commission on th 

 removal of obstructions in Hell-Gate recom 

 mended a plan which, as to its general features 

 was substantially the same as one that Lieuten 

 ant-commanding Davis had proposed in 1848 

 Instead of Maillefert's process of surface-blast 

 ing, they recommended drilling. This woul< 

 have had to be done from within a diving-bel 

 which was impracticable because of the cei 

 tain disturbance of the apparatus by currents 

 and the liability to collisions from passing ves 

 eels. All of the plans so far proposed seem t 

 have been limited to removing the smalle 

 rocks lying in the channel ; the possibility c 

 clearing away the larger reefs was not yet con 

 ceived. 



Work with the Drilling-Scow. In 1866 the en 

 gineering department instructed Gen. Job 

 Newton to make an examination of Hell-Gate 

 and present a plan and estimate of the opera 

 tions necessary to improve its navigation. 1 

 report was submitted ii 

 January, 1867, with ai 

 estimate for removin; 

 the reefs by blasting 

 after drilling the sin- 

 face from a fixed plat 

 form above the water 

 In whatever plan migh 

 be decided upon, i 

 was considered essen 

 tial that the drills 

 which, to avoid inter 

 ference from currents 

 were to be worked witl 

 in iron tubes reaching 

 from the platform t< 

 the rock, should be at- 

 tached to a framing kept absolutely fixec 

 while the drilling was going on ; and tna 

 the divers, or the machinery necessary t 

 handle and remove from the bottom the roc* 

 blasted, should be protected from violent cur 

 rents. It was proposed to accomplish the Jat 



