

/--.A-.-V. 221 



minimum. Such a mode of regulating currents was present in 

 my mind when, in addressing the Iron and Steel Institute in 

 March, 1877, I ventured to express my conviction that natural 

 S such as represented by large waterfalls, could be utilised 

 for the production of motive power and electric light, in towns at 

 a distance of even 30 miles from such source, by means of a large 

 electric conductor. This suggestion gave rise to a good deal of 

 discussion and criticism, especially in the United States ; but I 

 replied to some of these criticisms in delivering one of the Science 

 Lectures at Glasgow in March last, having already referred to the 

 matter in a discussion that was held before the Institution of Civil 

 Engineers on the 29th of January last. Having in the meantime 

 perfected the regulator, I showed it in operation at the soiree of 

 the Royal Society on the 19th of June, and have only been waiting 

 to get experimental data complete, in order to bring the whole 

 subject before one of the scientific bodies. The arrangement may 

 be said to consist simply of a thin strip of copper or silver, say 

 6 inches long and half an inch broad, stretched horizontally 

 between two supports, with a weight or spring exerting a certain 

 pressure in the middle. The branch circuit to be regulated is 

 passed through this strip of metal, which is thereby heated to a 

 certain moderate extent, depending upon the amount of current 

 passing, and upon the rate of radiation of the heat produced in 

 the strip to surrounding objects. Suppose that when the normal 

 condition of things obtains, the strip of metal is maintained at 

 the temperature of, say, 100 Fahr., and suppose that by an acci- 

 dental approach of the carbons of a lamp, the resistance of the 

 circuit is suddenly decreased, an almost instantaneous increase of 

 temperature of the thin strip will ensue, which will cause it to 

 elongate slightly, and allow the weight resting in the middle to 

 descend, which in its turn causes an increase in the resistance of 

 a small rheostat, through which the branch current in question 

 has to flow. 



It will thus be seen that it is not so much the novelty of the 

 announcement made by Mr. Edison, as the manner in which it 

 has been conveyed to us that has alarmed a portion of the British 

 public, and I hold that such startling announcements as these 

 should be deprecated, as being unworthy of science and mischievous 

 to its true progress. 



