ON LIGHT HO USE APPARA TUS. 315 



in feet. At that speed with the best form the resistance is about, as I 

 said, one two-hundredth part of the ship's weight. 



The PRKSIDENT: Ladies and gentlemen Every one who has 

 listened to Mr. Fronde's lucid explanation must have been struck by 

 the important bearing which his experiments must exercise upon naval 

 architecture. Not long ago it was supposed by every naval architect 

 that the chief element of the resistance of a ship going through the 

 water was its mid-ships section, and that if only the mid-ships section 

 could be cut down the total resistance of the chip would be reduced 

 and its speed increased. 



Hence the tendency to add to the length of the ship, by which we 

 reach the proportion of one in ten. Mr. Froude's experiments prove the 

 fallacy of that train of reasoning, and show that the midships section has 

 really nothing to do with the resistance of the water. That resistance 

 is made up by the skin resistance and by the waves engendered by the 

 rapid motion of the ship through the water. Hence this new principle 

 will give rise to new results, and the ship of the future will no doubt 

 differ very materially from the ship of the past. I wish now to propose 

 a vo*e of thanks to Mr. Froude for his very interesting communication. 



The Conference then adjourned for luncheon. 



On re assembling the President called upon Mr. Thomas Stevenson 

 to read his communication 



ON LIGHTHOUSE APPARATUS. 



Mr. THOMAS STEVENSON then made the following extemporaneous 

 statement : Perhaps I ought in the first instance to explain that the 

 object of my being asked here is not to give an address upon the subject 

 of light-houses generally, but merely to describe certain of the more 

 important irfiprovett'iCfitfi which originated in Scotland, and which have 

 been illustrated by models in the museum, some of which are now on the 

 table. 



There arc many interesting subjects connected with lighthouses, to 

 which, therefore, I shall not refer ; for example, I shall not need to 

 refer to the electric light which emanated from the researches of our 

 illustrious countryman Faraday, and which in the hands of Professor 

 Hoimes and the Trinity House of London, has been cairied out so 

 successfully. Nor shall 1 need to refer to the very interesting experiments 



