646 PROCEEDINGS OF SECTION H. 



keeping the tips of the blades turned shghtly upwards. Phillips 

 did this by actually curving his steel blades upwards near the 

 tips. Sadleir let his wooden and somewhat flexible blades over- 

 hang their supports, so that when the boat would roll the lower 

 projecting ends of the blades would take an upward turn, and 

 this, he found, helped the boat to right itself. He found that a 

 rigid blade tended to sink further beneath the surface when the 

 boat rolled to one side. While Phillips, then, employed one blade 

 to carry practically the whole weight of his boat, Sadleir employs 

 several, the number depending upon the weight to be carried, and 

 they are all of the same size. In some of his hydroplanes he places 

 his blades in tiers, one above the other, so that as the speed 

 increases the boat rises and certain of the blades are lifted quite 

 out of the water and thus put out of action. 



In Sadleir's experiments his narrow blades kept at about the 

 same level, cutting through minor waves. On larger waves, such 

 as followed in the wake of the motor launch, which towed the 

 hydroplane, the latter simply adapted itself to the slope of the 

 wave. The pull on the towHne was, however, heavier when the 

 hydroplane was travelling uphill than when travelling downhill. 

 The following are the results of some of the experiments. The 

 speeds were ascertained by one of Walker's patent logs. The 

 pulls were measured by spring balances. 



The craft kept remarkably steady. Small as it was, the lads 

 who were on board could stand up, sit down, or move about with- 

 out affecting the stability of the vessel. 



