Notes

Abstract

THOSE engineers who have been advocating the electric drive of ship propellers will read with mixed feelings the announcement made on January 2 by Mr. Daniels, the Secretary of the U.S. Navy, that in the future all the capital ships of that Navy will be electrically driven. There is no reason to doubt that the new American Dreadnought—the New Mexico—is a great success. Steam turbines are used, and in order to get their highest efficiency they must be kept running at high speeds. The ship's propellers run at much lower speeds, and so direct driving is out of the question. The turbines are directly coupled to dynamos, and the electric power generated is transmitted to motors directly coupled to the propellers. The relative speed of the turbines and the shafts can be adjusted to any desired value with the greatest ease by merely turning the controller-handle. The experiments undertaken in this country a few years ago were carried out in a timid and hesitating way both from the engineering and the financial point of view, and the results were generally disappointing to the electrician designers. It is possible, but by no means probable, that slow-speed turbines may be developed in the future. In the meantime, we hope that British shipbuilders will make larger use of the electric drive in the future than they have in the past.