Proceedings. 95 



current previously evolved from magneto-electric and 

 dynamo-electric machines. The sub-division of the iron of 

 the armatures was a marked advance over earlier forms, as 

 indicated by the great increase of electrical duty obtained, 

 which is now, in the best practice, as high as 95 per cent of 

 the mechanical power absorbed by the dynamo-electric 

 machine. Various subsidiary improvements have also been 

 made by several inventors in the winding of the electro- 

 magnets of dynamo-electric machines, having for their 

 object the automatic regulation of the amount of electricity 

 generated to the amount of electric power required in the 

 external circuit. 



" I may also be permitted to mention in connection 

 with these improvements my discovery of the synchronous 

 rotations of the armatures of a number of dynamo-electric 

 machines, by which their united power can be obtained 

 without the use of mechanical gearing. This discovery, 

 which was first announced at a meeting of this Society in 

 the year 1868, is largely utilised in the United States of 

 America, and is now in course of further development at 

 the electro-mechanical power station below the Falls of 

 Niagara. The principle has also been applied with some 

 success at general lighting stations in this country and on 

 the Continent. I am also pleased to note the fact that, the 

 largest and most powerful dynamo-electric machines at the 

 Corporation Electric Supply Station, although associated 

 with other names, are, in their main features, built according 

 to the designs of my original generator of electricity as 

 described and figured in the Philosophical Transactions of 

 the Royal Society for the year 1 867. 



"Since the expiration of the controlling patents for 

 dynamo - electric machines, the manufacture of these 

 machines has become a considerable industry, in which a 

 large amount of capital is invested, affording employment 

 to many thousands of persons. 



