Page:The Steam Turbine.djvu/62

 of equal success on a large scale for the transmission of large powers.

Preliminary experiments were made some years ago on helical reduction gear, which showed a mechanical efficiency of over 98%, and a 22 feet launch was constructed in 1897: the working speed of the turbine was 20,000 revolutions per minute, which was geared in one reduction of 14 to 1 to the twin screws. The speed attained was 9 miles per hour, and this little boat was many years in use as a yacht's gig. She was the first geared turbine vessel. The next step was to test geared turbines in a typical cargo boat, and the "Vespasian" was purchased in 1908. She is of 4,350 tons displacement, and was propelled by a good triple expansion engine of 900 horse-power. After thoroughly overhauling and testing her existing machinery for coal and water consumption, to make sure that it was in thorough good order, the engine was taken out and replaced by geared turbines, the propeller, shafting, and boilers remaining the same. On again testing for