The Newark journal., 1902-02-28
A TOY OCEAN.
One Constructed at Was hington to Test
 Ships for the Navy.

Ships for the Navy.
 A quarter of century ago an Eng fish naval constructor, Dr. William Froude, performed a series of experi- ments with scale models designed to predetermine the resistance of ships being built for the navy. He made small models of the vessels to be con- structed, giving great care to the preservation of the scale and these models he then lowed through the water, under varying conditions, by mechanism extremely sensitive to variation in the pull. The tension in each ease was carefully recorded, and conclusions drawn as to the lines most favorable for speed. To verify his re- suits a British man-of-war was lowed by another vessel, and the actual pull on the tow rope was carefully meas ured and compared with the results of experiments made with small model. The two sets of answers were so nearly alike as to leave no doubt of the praetieability of actual experi- ments with reduced scale models.
 At the Washington navy yard model basin for experiments of this kind has been constructed, at cost of $100.000.
 Within building designed to pro- tect it from all disturbing conditions of the atmosphere is a tank of pure, fresh water, 310 feet long and 43 feet wide, with a uniform depth of II feet Spanning this narrow sheet of water Is movable bridge, set upon steel rails, which run parallel to the length of the basin. Heavily built, and fast ened and braeed so rigidly as to avoid all unnecessary vibration, the bridge is provided with a wonderful motor, which can drive it along the rails, if need be, at the rate of 20 knots an hour.
 The model of the proposed ship, cut from soft pine, conforming as nearly as possible 10 a uniform 20-foot length. and ballssted with the utmost care, is firmly fastened to ali arm which projects from below the cen- ter of the bridge or towing carriage, as 1t is called. On the carriage are placed all the delicate dynamometrical mech anisms which record the @pulis of the model as t glides through the water beneath the span of the bridge. This 1 multiplied by the proper ratio must establish accurately the power that will be berequired tooyereomet theresist ance of the finished vessel.
 Thanks to an almost fawIess elec- trical development, the bridge moves forward with an even motion, with out trace of the rattle and jonnce Of an electric car.
 Besides the motormen, there are two persons on the carriage duringan l experiment They watch the pens of i the recording cylinder of the dyna- mometer. These pens, by means of electricity register the actual distance travcrsed. together with the varying pull of the model as the speed changes.
 When all is ready fer an expert ment, at the clang of a gong the bridge starts from the south toward l the north end of the tank, while be- heath t the 20-foot warship glides evenly through the filtered water. As the run hears its end and the specta- tors wonder how the great bridge with is precious freight of instru- ments is going to escape collision with l the wall ahead, two great hydraulic brakes operate automatically and bring the mass to a gentle stop with out jar or quiver-Youth's Com.