96 THE AMERICAN ENGINEER [February, 1894. bustion and the importance of proper management of fires to produce the greatest results with the least expenditure of fuel. It has been said that this is greatlyevercome by the applica- tion of mechanical stokers, but this is a mistake well known by those conducting tests, the results being ‘always superior with the greater intelligence of the operator'of the machine. What is greatly needed at present is to lay aside the idea that any one is good enough to fire and manage boilers. The rea- son why a better class of skill is not obtained for this work is that it is not sought, and just as long as this class of operators is looked upon as mere shovelers, throwers of coal and car- riers of water, ignorance, with all its attendant waste, destruc- tion of property, and general demoralization, will be promi- nent in the department. As a fitting close it would be proper / llllllllllllmumanmn Ifh lltlltll ‘£1 . ill [I i .4!!! 1111 t ..‘.hlt WW 3, THE BLAKE VERTICAL TWIN AIR—PUMP ON THE U. S. CRUISER “NEW YORK.” to ask what degree of intelligence or knowledge would qualify one to fire boilers properly? 1. That the fire should be maintained with uniformity, and that no openings, in the form of bare places, showed upon the bars to permit cold air to pass through. 2. The judgment that will enable him, by a glance at the ilisll-pit, to know at once, to a great extent, the condition of the res. 3. He should- know something of the various fittings of the boilers, such as valves, etc., and the details of the furnaces. But not least, an ambition to grasp the details, so as to qual- ify him for a still higher plane, which would certainly follow. provided there was judgment enough in the superior to note such details. Sufficient, we think, has been said to convince the most ob- tuse mind that the indiscriminate employment of labor for this purpose is a crying evil, and some consideration given to the It claims here made, that, simply becauseone can shovel and throw, it does not follow that he IS qualified to fire and have charge of steam-boilers. A. v AIR-PUMPS oN THE UNITED STATES CRUISER “NEW YORK.” - OUR readers will remember the illustrations in our last num- ber of the United States armored cruiser New Y0?‘/c. We now publish particulars of the independent air-pumps, which in theirgway are quite novel in construction and performance. Thejzcruiser New York, like all the Government vessels, has . very little room to spare for the engines and their auxi- liaries. consequently the design of the ai_r-pump had to be one combining compactness, minimum weight, and maximum efficiency. As shown by the illustration, the design of this pump is of the vertical twin single-acting type, Blake system. The air cylinders are of the well- known vertical, single-acting type, operated by steam cylinders on the direct-acting system; there being two air cylinders, the operation is practically continuous or double—acting. The piston-rod on each side of the pump is connected to the beam by means of links, etc. The air cylinders and the workin g parts of same are entirely of gun-metal composition, which is the usual practice in the United States Navy. The piston-rods in the steam cylinders, as well as the valve gear, are of steel, and the latter is so arranged that it can be adjusted by hand even at all times. - These pumps are particularly remarkable for their economy——that is to say, for the low percentage of the power required in comparison with the power of the main engines. From the ofiicial report of the trial trip the in- dicated H.P. of the Blake air pumps was less than one- quarter of 1 per cent. of the indicated I-LP. of the main engines, a result that has, we believe, never before been attained in marine engine practice. The explanation for this small amount of power required to do the work is perhaps due to the very complete and perfect arrange- ment of the steam valve gear, which thoroughly controls the operation of the pump, so that a very low rate of pis- ton speed is sutlicient to give a first-class working vacuum. As an illustration, the average speed of the air—pumps on the trial trip of the New York was less than 16 double strokes per minute, while the minimum speed was only 94,; double strokes per minute. The pumps are so posi- tive that they can be run at practically any speed desired without the slightest danger of being caught on a dead center, a feature which, of course, is impossible with a crank and fly-wheel type of independent air—pump. In fact, these pumps have been so successful that the William Cramp & Son Ship & Engine Building Company have placed them on all the other Vessels they are building for the Navy——namely, the Coltcmfnla, Mz'm1eay90lz's,' Broolclg/n, Indicma, Massachusetts, and Iowa. Each of the New York’s air-pumps has two double- acting steam cylinders 12 in. diameter, two single—act- ing air cylinders 25 in. diameter, the stroke of all being 18 in. ‘ The working parts of this pumping engine are exceed- ingly simple and strong. The valves for the steam cylin- ders are plain D slide-valves, which are operated through levers by a supplementary piston moving in the horizon- tal steam cylinder shown. This supplementary piston is in turn operated by a plain D valve connected to the valve-rod, having adjustable collars for regulating the stroke. This valve-rod is moved by means of the rod at- tached to the working-beam from which it gets its motion, and . which is clearly shown in the engraving. New Material for Electrodes".-A species of fungus has been found to be well adapted for the making of electrodes for external use in electro-medical operations. Felt. cotton and clay have not been altogether satisfactory for this pur- pose. The fungus grows on old trees in Europe. When pre- pared for the above use it has the appearance of soft leather, and is very porous. It is found to be an excellent conductor, and besides readily conforms to the irregularities of the body. F ast English Cruiser, the “ Destroyer.”-—The Admiralty have placed an order with the Naval Construction Company, of Barrow, for a first-class cruiser. She is to be 300 ft. long, with a speed between 23 and 24 knots. . while the pump is in operation, thus securing full stroke -