438 POPULAR LECTURES AND ADDRESSES. 



work of a horse-power. Parenthetically, in ex- 

 planation, I may say that the French metrical 

 equivalent (to which in all scientific and practical 

 measurements we are irresistibly drawn, notwith- 

 standing a dense barrier of insular prejudice most 

 detrimental to the islanders), the French metrical 

 equivalent of James Watt's "horse-power" of 550 

 foot-pounds per second, or 33,000 foot-pounds pcr 

 minute, or nearly two million foot-pounds per 

 hour, is 75 metre-kilogrammes per second, or 4* 

 metre-tons per minute, or 270 metre-tons per 

 hour. The French ton of 1,000 kilogrammes 

 used in this reckoning is 0-984 of the British 

 ton. 



Returning to the question of utilising tidal 

 energy, we find a dock area of 162,000 square 

 metres (which is little more than 400 metres 

 square) required for 100 horse-power. This, 

 considering the vast costliness of dock construction, 

 is obviously prohibitory of every scheme for 

 economising tidal energy by means of artificial 

 dock-basins, however near to the ideal perfection 

 might be the realised tide-mill, and however 



