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Dynamic Balancing Ap turbine rotor, considerable diffi- culty is experienced in having it come from the machinist's hands in perfect balance. Static balance, which permits a piece to remain in any po- sition when placed on level ways, in- volves no great difficulty. However, a body may be in perfect static bal- ance and develop a centrifugal couple leading. to severe vibration at high rotative speeds. To overcome this objection as eco- nomically as -possible, the Carlson- Wenstrom Co., Philadelphia, has de- veloped the balancing apparatus shown in the accompanying illustration. The object to be balanced is supported and rotated on a bed which is fixed at one end but free to vibrate at the other end in one_ place only, under the influence of the un- balanced moment. Below, and paral- lel to the body under test is another shaft suspended from the bed and turning in the same direction at the same speed. On the lower shaft are weights which may be shifted while running to produce a centrifugal couple of variable but accurately measured amount. By .varying the plane of these weights, and the distance be- tween them, a position is found in which the unbalance due to the [' FINISHING a crankshaft or a known weights exactly neutralizes the . unbalance in the object tested. The piece under test is now corrected by drilling holes in the proper places or removing stock with a grinding wheel. The. estate of W. I. Babcock and . Babcock & Penton, consulting naval 'architects and engineers, New York City and Cleveland, announce that the business was. dis- 7 RECUPERATIVE GAS OVEN FURNACE OF NEW TYPE tneans for rapid facsimile photographic reproductions of letters, signatures, legal papers, maps, drawings, blueprints, financial statements, books, archives or any written or printed documents. snore paratus--Recuperative Gas Oven Furnace ire Separain is practically a large camera equipped with a self-contained arrangement for developing and fixing the prints, photographic copies being made direct without preparing a trans- parent negative. The booklet is illus- trated and describes the apparatus in full: Recuperative Gas Oven Furnace With the. cost of all 'kinds of fuel used for industrial purposes advancing steadily, heating furnaces are being sought that will: give the maximum amount of heat while consuming the minimum amount of fuel. The recu- perative furnace shown. in the accom- panying illustration has recently been placed on the market by Tate-Jones & Co., Pittsburgh. This furnace embodies novel features and it is claimed that it is economical in operation. The base or pedestal on which the furnace rests is cast iron while the outer case of the furnace is cast iron and boiler plate. The hearth walls are lined with highly refractory material. The burners are designed -on the so- called blast system in which the gas and air are mixed at some little dis- tance from the point of combustion. The burners, which are connected di- rectly to a manifold, deliver the ignited fuel under. the hearth. Among other features may be mentioned the fact that the thermocouple lies in a recess in the hearth, also the size of the vent that carries away the burned gases has been given consideration. With the object of salvaging as far as possible the burned gas. that other- wise would escape without performing its full quota of work, a _ recuperator has been added to continued May 1. Communications | 'may be addressed to -H. Penton, Penton building, Cleveland. The Commer- etal' Cameta. Co., Rochester, N. Y., has. recently is- sued a 16-page booklet describing its line of photo-- graphic copying machines. It. is pointed out that the apparatus fur- nishes a simple this furnace. The advantages of re- cuperation are many, for aside from saving fuel it is said "that 4 better furnace tem- perature is main- tained, inasmuch as practically all the fuel is com- pletely oxidized be- fore leaving the combustion cham- ber. The recuperator consists of a coil of wrought iron pipe treated espe- and practical o DYNAMIC BALANCING APPARATUS 270 cially to eliminate oxidation.