Nikola Tesla U.S. Patent 1,061,206 - Turbine Patent Wrapper Page 39

JJLJUD(303UUUULILJUCUJ center through the three openings at both ends into the exhaust chamber. I recognize photographs G and H as showing the two 200 HP turbines installed at the Edison Waterside Plant, New York City, and I know that these machines were constructed and operated in accordance with the descriptions and illustrations in the above mentioned applications for patent. They were coupled together by a torsion spring shown in photograph H so that horse power measurements could be taken without recourse to reduction gears, one turbine to be used as a driver and the other as a brake. The Tesla turbine is particularly valuable on account of its reversibility, its efficiency being the same for both directions of operation. Other advantageous features are its its extreme simplicity, its adaptability to varying speeds without the marked drop in efficiency which is unavoidable in bucket turbines. The great torque and low speed which it possesses makes it especially adaptable for traction work, and by its compactness and small weight per horse power yield it is superior to existing machines. ty It is also a prominent characteristic of the Tesla turbine, and this is a matter of the greatest practical importance, that there is a very much smaller slip or relative velociof steam and metal surface than in any other practical forms turbines. This contributes very greatly to its efficiency. I may also note that I believe it is the only turbine which utilizes the viscosity of the steam to transmit the kinetic energy of the intermediate layers between the disks to those of -838 903