In the same building with the mine pump gearing is a duplicate arrangement for operating the man engine. In order to operate the mine pumps and man engine for the Hecla mine, it was necessary to use rock shafts, which are made of gun iron, and hollow; they are 32 inches in diameter outside, with 4½ inches thickness of metal. The pump rock shaft is 39 feet 4½ inches long over all, in two sections, and weighs 40 tons. There are rockers placed on each end of this shaft, one of which is connected with a crank on the mortise wheel shaft, and the other with the surface rods that work the pump-bobs. These rods are of Norway pine, 12 inches by 12 inches in section, and 1,000 feet long. There are two bobs, one above the other, with axes at right angles, each weighing about 25 tons. The connection from the upper bob to the lower has hemispherical pins and brasses to accommodate vibrations in right angled planes. The slope of the main pump is 39 degrees, and the machinery has been designed to raise water from 4,000 feet depth. The pumps are of the usual Cornish plunger type, with flap valves. There is an auxiliary engine, of the Porter-Allen type, for driving the pumps and man engines when the main engine is not working.
It makes a 160 revolutions per minute, the same as the rope wheels The seeming complication of the arrangement is due to the fact that it had to be adapted to existing works, for increased depths, and put in without interfering with the daily operation of the mine.
The Calumet & Hecla Mining Company has also an extensive pumping plant at its stamp mills, which are located on the shore of Torch Lake, about four and a half miles from the mine. There are located here 3 pumping engines; two of which have a capacity of 20,000,000 gallons a day, and a third 10,000,000 gallons a day. The water is elevated between 50 and 60 feet, and is used for treating the stamped rock. Two of the engines are of the inverted compound beam and fly-wheel type; and the third is a geared pump, which has a horizontal double acting plunger, 36 inches in diameter, by six foot stroke, driven from the crank of a spur-wheel shaft.
The spur wheel is 12 feet diameter, 24 inches face, and contains 96 teeth. The pinion engaging with it has 27 teeth, and is fast on the fly-wheel shaft of a Brown horizontal engine, having a cylinder 18 inches in diameter, and a stroke of four feet. The steam pressure used is 110 pounds per square inch; and the engine has a Buckley condenser. The pump valves are annular, of brass, faced with rubber, and close by brass spiral spiral springs. Their external diameter is six inches, and the lift is confined to ½ inch. There are 91 suction and 91 delivery valves at each end of the pump. The maximum speed of this pump is twenty-six double strokes a minute.
The largest of the compound engines is named Ontario, and has a vertical low pressure cylinder 36 inches in diameter, and an inclined high pressure cylinder 17½ inches in diameter; the stroke of both being five feet. These are inverted over a beam, or rocker; and the pistons are connected to opposite ends of the same.
The beam attachment of the main connecting rod is made to a pin located above and midway between the pins for piston connections.
The main center of the beam and the crank shaft have their pedestals in the same horizontal plane. The throw of the crank is five feet. There are two differential plunger pumps, having upper plungers 20 inches in diameter, and lower plungers 33 inches in diameter, with a stroke of 5 feet. These pumps are vertical, and placed beneath the engine bed-plate, to which they are attached by strong brackets. The pump under the low pressure cylinder is worked directly from its cross-head by an extension of the piston rod. The other pump is worked by a trunk connection from the opposite end of the beam. The radius of the beam is but fifty inches, but the connections to it are made very long by links.
The lower plungers work through sleeves in diaphragms located in the center of the pumps. In these diaphragms, the openings for the delivery valves are made. These valves are similar in construction to those previously described for the horizontal plunger pump. Their diameter, however, is but 5¼ inches, instead of 6 inches, and there are 72 suction and 72 delivery valves for each pump. It will readily be seen that the action of these pumps is similar to that of the bucket and plunger; each pump having one suction and two deliveries for each revolution of the engine. The Ontario is designed to run at a maximum speed of 33 revolutions a minute; and the service required of it is to run regularly 144 hours a week, without a stop, which is performed with the utmost regularity.
The differential pump was invented and patented, many years since, by a party named James Ramsden, in Pennsylvania, who designed it for an ordinary house pump. It was subsequently reinvented by the writer, who first ascertained that he was not the original inventor upon applying for a patent. A pump of this description was run at the Hecla mine for several years, at a speed of 500 feet a minute; and its performance was in every way satisfactory.
This class of machinery deserves a prominent place, as the number in use vastly exceeds those of all other types combined.
The first consideration will be given to the Worthington, which is the pioneer of its type, having been invented by the late Henry R. Worthington, and patented in 1844. Mr. Worthington's first pump was designed for feeding boilers. His first water works engine was built for the city of Savannah, Ga., and erected in 1854. The second engine, which was the duplicate of the Savannah engine, was erected at the city of Cambridge, Mass., in the year 1856, and was guaranteed to deliver 300,000 gallons in twenty-four hours to an altitude of 100 feet. It had a high pressure cylinder 12 inches in diameter, placed within a low pressure cylinder 25 inches in diameter; the low pressure piston being annular. The double acting water plunger was 14 inches in diameter, and worked directly from the high pressure piston rod; the stroke of pistons and plunger being 25 inches. This engine was tested in 1860, with the result of a duty equal to 70,463,750 foot pounds per 100 pounds of coal. Subsequently, a test made by Mr. Frederick Graff, of Philadelphia (long prominently connected with the Philadelphia Water Department), and the late Erastus W. Smith, of New York, developed a duty of 71,278,486 foot pounds per 100 pounds of coal, which long remained the best record in the United States. In 1863, Mr. Worthington brought out at Charleston, Mass., his crowning success, the duplex engine, which fairly deserves to be placed first among the hydraulic inventions of this century.
This engine has since been more extensively duplicated for water works purposes than any other, with the possible exception of the Cornish.A paper read at the Montreal Meeting of the British Association.