The white cabinet is a piece of Edison's poured concrete furniture, while the other one is the ordinary wooden phonograph cabinet.] [Illustration: MODEL OF EDISON POURED CONCRETE HOUSE This little house, which stands on a table in Edison's laboratory, shows what he expects to do with the poured concrete house.] He turned the valve and the water certainly did flow. Instantly a stream that would have filled a barrel in a very few minutes began to run out of the pipe into the upper part of the tank and thence into the lower tank. "This is only a toy," smiled the inventor. "There are only half a dozen disks--'runners,' I call them--each less than three inches in diameter, inside of that case. They are just like the disks you saw on the first motor--no vanes, blades or attachments of any kind. Just perfectly smooth, flat disks revolving in their own planes and pumping water because of the viscosity and adhesion of the fluid. One such pump now in operation, with eight disks, eighteen inches in diameter, pumps 4,000 gallons a minute to a height of 360 feet. "From all these things, you can see the possibilities of the new turbine," he continued. "It will give ten horsepower to one pound of weight, which is twenty-five times as powerful as many light weight aeroplane engines, which give one horsepower of energy for every two and one half pounds of weight. "Moreover, the machine is one of the cheapest and simplest to build ever invented and it has the distinct advantage of having practically nothing about it to get out of order. There are no fine adjustments, as the disks do not have to be placed with more than ordinary accuracy, and there are no fine clearances, because the casing does not have to fit more than conveniently close. As you see, there are no blades or buckets to get broken or to get out of order. These things, combined with the easy reversibility, simplicity of the machine when used either as an engine, a pump or an air compressor, and the possibility of using it either with steam, gas, air, or water as motive power, all combine to afford limitless possibilities for its development." Doctor Tesla calls the invention the most revolutionary of his career, and it certainly will be if it fulfils the predictions that so many eminent experts are making for it. It is interesting to think that although this latest and most modern of all steam engines is a turbine, the first steam engine ever invented, also was a turbine. Though most of us usually think of James Watt as the inventor of the steam engine, he was not the first by any means, for the very first of which history gives us any record was a turbine, which was described by Hero of Alexandria, an ancient Egyptian scientist, who wrote about 100 B.C. Hero's engine was a hollow sphere which was made to turn by the reaction of steam as it escaped from the ends of pipes, so placed that they would blow directly upon the ball.