MECHANICS AND USEFUL ARTS. 55 



off Salem, Mass. It will be ready by llie first of June, This 

 will be the largest and most powerful fog-whistle in the world. 



Forty-two ton Hammer. — In England a huge steam-hammer, 

 weighing 1,000 tons, is being made for the Russian government. 

 The hammer-head weighs 42 tons, the anvil-block 500 tons, and 

 it is to be used in forging steel guns. — Van Nostrand's Eng. Mag., 

 Oct., 1869. 



Steel-headed Baih. — Steel-headed rails are made at the Trenton 

 (N. J.) Rolling Mills by the following process : The steel which 

 is to form the head of the rail is first welded to a quite thin piece 

 of iron. The combined bar is then beaten and rolled down until 

 the iron is very thin and the steel reduced to about half its former 

 bulk. After this operation is completed, the whole quantity of 

 iron requisite to complete the bulk of the rail is added to the 

 bottom of the combined bar and welded to the thin layer of iron. 

 This process, it is asserted, doubles the strength of the weld 

 between the iron and the steel, — alwa^'s a difficult operation to 

 perform. The old process consists in welding the relative thick- 

 ness of iron and steel at one operation, but the new method is re- 

 ported to furnish better rails. — Van Nostrand's Eng . Mng., Oct., 1809. 



Centrifugal Pumps. — The great Appold centrifugal pump to be 

 worked in connection with Mr. Hawkshaw's important work, the 

 Amsterdam Ship Canal, is to lift 2,000 cubic metres, or, say, 

 440,000 gallons of water per minute. The lift is not great, but 

 for each foot of lift, the actual duty, irrespective of all losses of 

 effect, is 133^ horse-power. — Engineering. 



Inverted Siphon. — An iron-pipe, 11 inches in diameter, and 

 8,800 feet (one and two-thirds miles) long, has been laid in Tuo- 

 lumne County, California. It runs down a mountain, under a 

 creek, and up the ascent on the opposite side, under a perpendic- 

 ular pressure at the lowest point of 684 feet. — Journal Franklin Inst. 



A rapid Change of Gauge. — In Missouri, the INIissouri Pa- 

 cific Raihvay — a road nearly 200 miles long — changed its 

 line from the broad to the narrow gauge. Nearly 1,400 men 

 were engaged in the work ; and they labored with such celerity, 

 that the task was accomplished in 12 hours, and without inter- 

 rupting the business of the road. 



Large Blast. — The operation of blasting off the rocky head- 

 land of Lime Point, opposite Fort Point, and forming the north- 

 ern entrance to St. Francisco Bay, for a heavy water-battery, 

 has been conducted under the direction of Col. G. H. Mendell, 

 U. S. Engineers corps. Two blasts have already been made; 

 one with about 10,000 lbs. of powder arid a second with 24,000. 

 This second blast is supposed to be the largest ever used in mil- 

 itary engineering, and moved about 80,000 lbs. of rock. At the 

 point a tunnel had been run in a north-westerly direction into 

 the base of the hill, a distance of about 30 feet, where a chamber 

 was formed on the right to contain 3,000 lbs. of powder ; thence 

 the tunnel ran in a direction south of west 31 feet, where a cham- 

 ber was formed on the left for 6,000 lbs. of powder, thence on the 

 same line 45 feet, where the third chamber was formed to contain 

 7^500 lbs. These chambers were about 5 feet by 7 feet, to contain 



