Rayleigh's Address to the British Association. 93 



•quantity of air should remain — and it is interesting to recall that, 

 twenty years ago, such vacua were rare even in the laboratory of 

 the physicist. It is pretty safe to say that these wonderful results 

 would never have been accomplished had practical applications 

 alone been in view. The way was prepared by an army of scien- 

 tific men whose main object was the advancement of knowledge, 

 and who could scarcely have imagined that the processes which 

 they elaborated would soon be in use on a commercial scale and 

 entrusted to the hands of ordinary workmen. 



When I speak in hopeful language of practical electricity, I do 

 not forget the disappointment within the last year or two of many 

 over sanguine expectations. The enthusiasm of the inventor and 

 promotor are necessary to progress, and it seems to be almost a 

 law of nature that it should overpass the bounds marked out by 

 reason and experience. What is most to be regretted is the 

 advantage taken by speculators of the often uninstructed interest 

 felt by the public in novel schemes by which its imagination is 

 fired. But looking forward to the future of electric lighting, we 

 have good ground for encouragement. Already the lighting of 

 large passenger ships is an assured success, and one which will be 

 highly appreciated by those travellers who have experienced the 

 tedium of long winter evenings unrelieved by adequate illumina- 

 tion. Here, no doubt, the conditions are in many respects 

 especially favorable. As regards space, life on board ship is 

 highly concentrated, while unity of management and the presence 

 on the spot of skilled engineers obviate some of the difficulties 

 that are met with under other circumstances. At present we 

 have no experience of a house-to-house system of illumination on 

 a great scale and in competition with cheap gas ; but preparations 

 are already far advanced for trial on an adequate scale in London. 

 In large institutions, such as theatres and factories, we all know 

 that electricity is in successful and daily extending operation. 



When the necessary power can be obtained from the fall of 

 water instead of from the combustion of coal, the conditions of the 

 problem are far more favorable. Possibly the severity of your 

 winters may prove an obstacle, but it is impossible to regard 

 your splendid river without the thought arising that the day may 

 come when the vast powers now running to waste shall be bent 

 into your service. Such a project demands of course the most 



