88 ANNUAL OF SCIENTIFIC DISCOVERY. 







pump, through caustic potassa. The vessel is propelled by means of a 

 screw-propeller in the stern, turned by hand by a crank in the cabin. 

 A rudder is also operated in the cabin, giving those within a perfect 

 control of the boat. The propeller and rudder lever both pass through 

 stuffing boxes, which prevent the egress of air from the cabin, or the 

 ingress of water. The cost of this curious submarine vessel is about 

 $9,000 dollars. Scientific American, and Farmer and Mechanic. 



REMOVAL OF OBSTRUCTIONS IN "HELL GATE," LONG ISLAND SOUND. 



THE great terror to navigators through Long Island Sound, known 

 as " Hell Gate," or " Hurl Gate," as some choose to call it, is situated 

 opposite Harlem, eight or nine miles from New York Battery. The 

 East River, or Sound, from the Battery up to Harlem, runs a northerly 

 course. Here it makes a sudden bend, almost at a right angle, and 

 runs easterly for a mile or more, when it makes another bend to the 

 northward. Between these two bends in the Sound lies this celebrated 

 estuary, realizing to the mariner all the dangers and difficulties of 



t/ / <_} CJ 



Scylla and Chary Mis, pictured by the ancient poets. The eastern end 

 of Long Island Sound has a broad opening to the ocean, and as the 

 tide presses in from the sea, it finds a broad channel most of the way 

 through the Sound, eight, ten, or a dozen miles wide. When it reaches 

 this neck, between the two bends mentioned above, it is compressed to 

 about half a mile in breadth, producing a very rapid, wild current. 

 And it is here, in the midst of this rushing flood, that several rocks 

 and reefs rise up from the bed of the river, almost to the surface, and 

 throw the whole current into the wildest commotion. The most formi- 

 dable of these, and the most in the way, is Pot Rock, which lies nearly 

 midway in the channel. To the westward of this, and a little nearer 

 the northern shore, is the Fiying Pan. Way's Reef lies to the south- 

 ward of Pot Rock, towards the Long Island shore. 



Ever since the settlement of the country the navigation of the Sound 

 has been obstructed by these terrific barriers, and no hopes were enter- 

 tained that they would ever be removed. To drill and blast them, es- 

 pecially Pot Rock, was seen to be utterly impossible ; for no vessel, or 

 structure whatever, which man could raise, could be stationed upon it 

 to effect the drilling. At length, however, a few months since, a French 

 gentleman, by the name of Maillefert, advanced the bold assertion that 

 he could blow Pot Rock to atoms, without drilling, and clear it out of 

 the channel to a sufficient depth to render navigation over it safe at all 

 times of tide. The idea was regarded as absurd, and but little atten- 

 tion was paid to it. The assertion was repeated, and evidence was 

 produced that M. Maillefert had already performed a similar feat at 

 Nassau, New Providence, where he had, without drilling, blasted and 

 removed nearly a hundred tons of rock eighteen or twenty feet under 

 water. M. Maillefert offered to undertake the job of removing Pot 

 Rock, if the means were furnished to carry on the work, stipulating 

 not to receive a dollar for his own services till the work was fully ac- 

 complished. Some interest began, to be awakened upon the subject, 

 and at length Henry Grinnell, Esq., whoso liberality in aid of humane 



