What follows is a article first published in Scientific American, December 23, 1871. The removal of obstructive rocks from the narrow East River strait of Hell Gate began in 1849 and was accelerated in 1851 when the U.S. Army Corps of Engineers led by General John Newton began a blasting and dredging operation which lasted 70 years.
We give this week some engravings illustrating the operations now in progress for the removal of the obstructions at Hallett’s Point, East River. Having often referred to this great work, our present notice will be rather historical and general than technical.
History of the Work
The following sketch of the origin and progress of the work is from The New York Times:
“Complete surveys of New York harbor have been made at different periods, as is well known, with the object of removing the obstructions to navigation, by Admirals [David Dixon] Porter and [Charles Henry] Davis, Commodore [Tunis] Craven, and the present able and successful topographical engineer General John Newton of the United States Army.
“In September, 1870, experimental blasts were made by General Newton,which proved to him beyond a doubt that the work he had undertaken, though a task of immense magnitude, could be accomplished, and at a comparatively trifling cost to the Government.
“Last May, General Newton commenced work with the steam drills on the dangerous rocks, in mid stream between Governor’s Island and the Battery, known as Diamond Reef. After laboring assiduously for over five weeks, and making repeated blasts, between 700 and 800 yards square of the reef were blown away.
“Surveys were made of three blasts, which disclosed at the bottom of the river a mass of crushed rock, innumerable detached boulders, and huge hillocks of sand, lying around, and over which was once Diamond Reef.
“A contract was soon made to have the debris removed, a work which has almost been finished, and which has demonstrated the fact
that no additional blasts will be required, and that the dreaded Diamond Reef is no more.
“Soon after the work of the drills upon Diamond Reef was concluded, the drill scows were securely moored over Coenties Reef, and immediately commenced operations. The number of cubic yards of rock to be removed at Coenties Reef is roughly estimated at over 3,000, and much of this has already been blasted out by General Newton’s indefatigable workmen.
“Besides at Coenties Reef, General Newton’s drills are now at work on the Shell Drake, Way’s Reef, Hog’s Back, Pot Rock, at the Hell Gate, or Horll Gatt [sic] as the old Dutch navigators termed it [Helle Gadt was a name the Dutch once applied to the entire East River], and at Willett’s Point.
“The operations at the Hell Gate are the most extensive, the most important, and decidedly the most interesting. The Hell Gate, as every New Yorker knows, is a narrow, rocky passage in the East River, and in the old Knickerbocker times its raging current was the terror of the Dutch skippers and their heavy and unwieldy craft.
“Of late years, many improvements have been effected by blasting away the surface rock, and the most salient points of the jagged ridges; but only since August, 1869, has the United States Government commenced to deal with the dangers of Hell Gate in a measure corresponding with their importance.
“The operations undertaken by General Newton at Hallett’s Point, for the Hell Gate, involve the solution of an important problem of engineering as regards the most effective and economical process of submarine blasting. The modus operandi employed at Hallett’s Point is entirely different from the manner in which the work of removing the obstruction has been accomplished at Diamond and Coenties Reefs, and is what is technically termed tunnel blasting.
“At Hallett’s Point, in August, 1869, a coffer dam was commenced under the superintendence of General Newton, and was completed in October. The dam is an irregular polygon in shape, having a circumference of 443 feet and a mean interior diameter of about 100 feet. The darn is built between low and high water marks.
“The excavation of the shaft immediately followed the construction of the dam, and during the spring of 1870 the shaft was sunk to the depth of twenty-two feet below water.
“The theory of the mining operations contemplates the removal of as much rock as can be excavated with safety previous to the final explosion, the result of which will be the sinking of the remaining mass into the deep pit excavated for its reception.
“The mass of rock remaining for the final explosion will be supported by piers, each of which will be charged with nitro glycerin. These piers are simply a portion of the solid rock left still standing.
“From the bottom of the main shaft, tunnels proceed in all directions, and are ten in number. Each of the tunnels extends from 150 feet to 350 feet outward, and they are all connected together by cross galleries at intervals of twenty-five feet. The tunnels were
begun towards the close of July, 1870, the shaft being at the same time sunk to a line nearly forty feet below low water mark.
“The tunneling is really an object of a great deal of interest, as much from the novelty as from any other feature. The tunnels are of various cross sections, some over twenty feet in height, and varying in width from ten to fifteen feet.”
The “Improved Drill” of the American Diamond Drill Company, recently illustrated and described in the Scientific American, has been recently introduced into one of the headings, and, we are informed by General Newton, gives prospect of affording efficient aid in hastening the completion of the work, which will take probably two or three years more continuous labor.
As the work advances, room is made for more miners, and therefore the rate of advance may increase with the progress of the excavation.
The liberal views of the Engineer in Chief, General Newton, are rendering this work important in another respect. He has made it a sort of engineering arena for the trial of different explosives and drilling machines; and the relative value of most of the mining appliances in market will be determined during the progress of the work.
In this way, important contributions to engineering science will be made, whose value will be second only to the splendid results anticipated by the removal of the obstructions from the Hell Gate passage. These out of the way, the upper end of the island will become a scene of busy thrift, scarcely; less prosperous than that which fills with unintermitting hum the lower part of the city.
Although from Virginia, General John Newton (1823-1895) served in the United States Army during the Civil War, and later as Chief of the Corps of Engineers. Newton oversaw improvements to the waterways around New York City, into Vermont, including the Hudson River above Albany. This work is covered in detail in Thomas Barthel’s Opening the East River: John Newton and the Blasting of Hell Gate (McFarland, 2021).
Illustrations, from above: “Coffer Dam, Main Shaft, and Entrance to Heading, Hell Gate, East River”; Dimond Reef (Diamond Reef) and Coenties Reef shown on an 1866 US Coast Survey Nautical Chart; and “Section View of a Transverse Avenue, Hell Gate,” both from Scientific American, December 23, 1871.
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