648 PROCEEDINGS OF SECTION H. 



Of course, a great many more experiments are needed before 

 it can be determined with certainty what the best number of 

 blades is, and what their tilt should be to carry a given weight. 



Piecing the information together in a rough way, I estimate 

 that a hydroplane on Sadleir's principle, weighing in all one ton, 

 could be driven at 40 knots with about 30 or 35 actual horse- 

 power. Thorn eycro ft gets this speed with about 58 h.p., and 

 skimming does not commence until about 17 knots. He has a 

 nearly flat bottom to his boat (an ordinary craft), and a skimmer 

 of the same weight would require perhaps 200 h.p. for this speed. 



It still remains to be seen whether the gyroplane will cut 

 through gusts of wind as the blades of the hydroplanes cut through 

 waves of water. Boomerang experiments seem to show that they 

 will. 



Dr. Harve}^ Sutton gave an exhibition of boomerang throwing 

 in illustration of this paper, using some of Sadleir's gyroplanes 

 for comparison with ordinary boomerangs. 



LECTURES 



A LECTURE on " Irrigation in India " was delivered before the 

 Section by Professor Warren. Following is a brief abstract. 

 The lecture was profusely illustrated by lantern slides. 



The lecturer traced briefly the progress of irrigation from 

 ancient times to the present day, and stated that, according to an 

 ancient inscription, it appears that the perennial systems of irri-- 

 gation so successfully operated in India and elsewhere were intro- 

 duced by the hydraulic engineers of ancient Chaldea and Baby- 

 lonia about 2000 B.C. 



The basin system on the Nile in Egypt, and the various 

 systems of inundation canals in Egypt and India are also of ancient 

 origin ; the perennial systems derived from the large rivers in 

 India are, however, the work of the British engineer. The various 

 mechanical contrivances, such as the Persian wheel, were illus- 

 trated and explained by means of lantern slides, w^hich method 

 was freely used in the lecture to describe the weirs, anicuts, under- 

 sluices and canal headworks in connection with the irrigation 

 of the Punjab, the United Provinces, and in Madras. 



These magnificent works in India were explained in con- 

 siderable detail, and it was shown that they were all most remu- 

 nerative Government investments, and a source of inestimable 

 benefit to -the natives of India, in whose behalf they were con- 

 structed. The works dealt with more especially in the lecture 

 were the Bari-Doab, the Chenab, and the Sidhnai irrigation 

 colonies in the Punjab; the Upper and Lower Ganges canals 



