174 Master Minds of Modern Science 



for the turbine when it beat the reciprocating engine in 

 economy of steam and justified the proposal to apply the 

 turbine to main propulsion.' ' 



Then began work on the first turbine- driven ship. 

 Models about two feet long were made, and towed by 

 means of a fishing-rod in a small pond at Ryton-on-Tyne, 

 and afterward a six-foot model was made which was 

 driven by a powerful twisted rubber spring. The working 

 speed of the propeller was no less than eight thousand 

 revolutions a minute. 



This model was so satisfactory that the ship herself was 

 built. Turbinia, as she was called, was a tiny vessel, one 

 hundred feet long, nine feet beam, and with only three 

 feet draught, giving a displacement of forty-four tons. 

 Small indeed to hold an engine giving two thousand horse- 

 power. 



Her first trial was made in November 1894, and was 

 very disappointing. The propeller was a two-bladed 

 screw of thirty inches diameter. It was driven at the 

 tremendous speed of the turbine (for in those days, 

 remember, there was no gearing down), and the result was 

 excessive ' slip/ In other words, the screw spinning at 

 such furious speed (one thousand seven hundred and 

 thirty revolutions a minute) made a hole in the water 

 behind it, and caused what is called ' cavitation/ The 

 loss by slip, or loss of grip on the water, was very nearly 

 half the total power. 



A single four-bladed propeller next tried was equally 

 unsatisfactory, and Parsons then built multiple propellers, 

 three small screws on each of two shafts. By this means 

 slip was reduced to thirty-seven per cent, and a speed of 

 nearly twenty knots was reached, yet even this was not 

 satisfactory. There is not space here to describe all the 

 long, patient, and costly experiments which were carried 

 out before the problem was solved. Photographs of 

 ' cavitation ' were taken by means of an arc lamp. With 



