THE RECENT PROGRESS OF PHYSICAL SCIENCE. 743 



The present development of electricity on a large scale depends, 

 however, almost as much upon the incandescent lamp as upon the 

 dynamo. The success of these lamps demands a very perfect vacuum 

 — not more than about one-millionth of the normal 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 scientific 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 intrusted 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 promoter 

 is necessary to progress, and it seems to be almost a law of Nature 

 that it should overpass the bounds marked out by reason and experi- 

 ence. What is most to be regretted is the advantage taken by specu- 

 lators 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 encourage- 

 ment. Already the lighting of large passenger-ships is an assured 

 success, and one which will be highly appreciated by those travelers 

 who have experienced the tedium of long winter evenings unrelieved 

 by adequate illumination. 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 ex- 

 perience 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 institu- 

 tions, 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 coui'se, the most careful consideration, but it is 

 one worthy of an intelligent and enterprising community. 



The requirements of practice react in the most healthy manner 

 upon scientific electricity. Just as in former days the science received 

 a stimulus from the application to telegraphy, under which everything 

 relating to measurement on a small scale acquired an importance and 



