June, ,916.] CURRENT TOPICS. 875

transmit telephone messages to any distance, but how to introduce the voice in high-power stations in a practical manner is the great problem of radio telephony, and to this branch of work Professor Power is now devoting much attention. His device for introducing the voice is far from perfected as yet, but, from reports thus far received, successful results have been obtained. Operators at several stations on Cape Cod have reported recording the strain of well- known popular airs produced by a phonograph, and, in some instances, steamers entering Boston reported picking up the music lnore than IOO miles out from port.

The radio station is one of the most complete in the country. Students at Tufts College have the facilities at their disposal for experimental work, though the plant is owned by a private corpora- tion, and a number of valuable results have been developed by numbers of the Tufts Wireless Club.

Land Drainage by Means of Pumps. S. M. VVoomvaRi~. (United States Department of Agriculture, Bulletin No. 304, November 19 , i 915 . ) - -The drainage of low-lying lands by the use of pumping ma- chinery to lift the drainage water over levees into adjacent streams or other drainage channels is a recent development in this country. Along the banks of our larger interior rivers considerable areas of bottom land are subject to overflow from the adjacent streams during the high water occurring usually with great regularity throughout the spring and early summer months. Such lands in their native state do not become dry enough to be subjected to ordinary cultural operations until well toward the middle of the summer, and hence can not be used for growing ordinary crops. In this natural condition they are therefore good for nothing but pasture, and have accordingly but little agricultural value.

So long as there exists in a locality any unoccupied or unutilized higher land suitable for agriculture there is little demand for the use of lands lying so low as to require the use of pumps. But the present high price of agricultural land justifies a heavy expenditure for the conversion to a productive state of areas formerly considered almost valueless, especially in those regions where agricultural land values are particularly high, either on account of unusually favorable natural conditions or the proximity of large centres of population.

Drainage by means of pumps has been carried on in European countries for the last IOO years, and has been rapidly increasing in this country during the last 2 5 years. Through this extensive ex- perience, including numerous failures, a considerable amount of knowledge is now available on the subject of the proper arrangement and the requisite capacity of pumping plants. Notable examples of successful work of this character are found in Holland, eastern England, and in Ireland, while large marsh areas in both northern and southern Italy depend upon pumps for adequate drainage. The pumps which were first used were the well-known scoop wheel and

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Archimedean screws which were driven by windmills. In modem in- stallations, however, the pumps are invariably of the centrifugal type, driven by a steam, gas, or electric motor.

Performance of 3o,ooo-Kw. Steam Turbo-generators. ANON. (Electrical l.[/orld, vol. 67, No,. 2o, May 13, 1916.)--The extent to which the steam turbine has displaced the piston engine in large units is strikingly shown by the performance of the 3o,0oo-Kw. units recently installed in the Seventy-second Street Station of the Inter- borough Rapid Transit Company of New York. In 19oo this station housed eight Reynolds Allis-Chalmers steam engines of a double combination horizontal-vertical cross-compound design. Each unit was rated at 5ooo Kw., with a maximum rating of 75oo Kw. In a space no greater than taken by one of these units a 3o,ooo-Kw. tur- bine unit now stands, operated from the same boilers now equipped with underfeed stokers, and superheaters to give 2o0 degrees of superheat when the boilers are delivering three times their rated out- put. The boiler pressure is 2o 5 pounds per square inch gauge. The steam engines operated originally at 175 pounds gauge and no super- heat. The cost of the engines, generators, and condensers was $4o per kilowatt, while the cost of the new turbine and condensers is $9 per kilowatt. The steam engine water rate was 17 pounds per kilowatt-hour, as compared with about i 1.4 for the turbines operating under similar load conditions.

The performance of the unit in outclassing in operating efficiency, cost, space requirements, and ability to handle swinging loads amply establishes the enviable position of the steam turbine as a prime mover. The old engines, which at the time of their installation rep- resented the last word in engine design, found no purchaser but the junk dealer. It is also interesting to note that, although it was de- cided two years ago to use this new type of turbine, changes in the art and operation in the interim have been such that the company will now install a 7o,0oo-Kw. cross-compound unit with three generators, any one of which may be operated independently if desired. Thus this art of generating electricity in steam-turbine driven stations has advanced to a point where, up to load factors of approximately 6o per cent., a kilowatt-hour of electrical energy can be manufactured more cheaply by this means than by water power.

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