Morning journal and courier., 1885-10-12
FLOOD ROCK DESTROYED.
Successful Engineering Removes Dangerous Reef and Insures Saf NaVigatiOn.

Successful Engineering Removes a Dangerous Reef and Insures Safe Navigation.
 NEW YORK, Oct. 1.-The great explosion which has been looked forward to so long was successfully fired Saturday morning at 11:15. Thousands of people viewed the sight from different points on the surround ing land. Mary Newton, daughter of Gen eral Newton, aged eleven years, was the one that touched the button of the electric bat tery that exploded the mine She was the same girl whose finger pressed the button, closing the circuit on the Hallett Point ex- plosion in 1876. Over ,00O pounds of dynamite and rackarock were used to bring about the plan of destruction.
 The disturbance occasioned was slight. The ground at Astoria, Blackwell's and Wards Islands trembled as if from a faint earthquake shock. City Hall in the city was jarred. No damage resulted to walls of buildings. Men of science were stationed at various points in the vicinity of the explo- sion yesterday with the concerted object of determining the velocity of the transmission of the shock through the crust of the earth. They had made arrangements to have the time of the vibrations taken, in case there were any, at Princeton, Tarrytown and New Brunswick, at Vassar and Yale colleges, and Harvard university, and at the observatory in Washington. Professor Clark, who was with Professor Mendenhall at Wards Island, said that they had not yet had time to com- pare notes. He regretted the delay that oc- cured in setting off the explosion, as he feared that many observations he had count ed on being made in distant places had been lost in consequence. Thus Professor Paul, at Staten Island. after watching until about 11:10 o'clock, gave up under the supposition that the explosion had taken place without shock appreciable there.
 In the wall in the basement of the Insane Asylum at Wards Island Professor Menden- hall stood before heavy weight depending from from hook in the wall, from the bot tom of which needle projected pointing earthward, and resting on the arm of lever in such manner that the slightest jar would displace it. When the explosion occurred the needle wss displaced, permitting the oth- CT arm of the lever to drop into 8 basin of mercury, thus closing an electric circuit which recorded the time of the explosion in the chronograph.
 At about noon dispatch to General Alp bolt from Lieutenant Spencer, the observer at Patchogue, said the vibration was felt there in 21 E seconds after the ex- plosion. The distance is AS miles, Lieu tenant Hale telegraphed from Pearsalls that the vibration was felt there in a little less than seven seconds; distance 1SI miles.
 The force of the explosion was about equal in all directions. Many theories were ad- vanced regarding the leaving of dangerous points which would not be broken up. What few soundings have been made show that the entire honeycombed reef was blown into thousands of small pieces that can be readily removed. Where there has been about four or five feet of water over the lodges vessels can soon find thirty or forty. Operations of removal will be commenced immediately and the once dangerous Hell Gate will be robbed of it's Derils