Figure 38. — One of the first forms of the 

 AlUance machine. Note the brushlike cur- 

 rent collectors. Reproduced, with permission 

 of the publisher, from O. Mahr, Die Entstehung 

 der Dynamomaschine (vol. 5 of Geschichtliche 

 Einzeldarstellungen am der Elektrotechnik, Berlin, 

 J. Springer, 1941), p. 89, fig. 61. 



tests were held at South Foreland during the winter of 

 1876-1877 under the joint supervision of Professor 

 Tyndall, successor to Faraday as scientific adviser 

 to Trinity House, and James N. Dougla.ss, chief 

 engineer of Trinity House. 



The results of these tests (see table 1) showed the 

 new dynamo to be far superior to the magneto 

 generator.'- Of the two dynamos, the Siemens 



ta ;i — ~ 



fp'!-!^ 



— ] 



d'dE 



m'- 



t^ 



Figure 39. — The usual form of the Alliance 

 generator as provided with a commutator. 

 From Annales tclegraphiques, 1862, vol. 5, pi. 5. 



the magneto generators, which had already been found 

 reliable. 



The attention of Trinity House was again brought to 

 the new machines in 1876 by an exhibition of the 

 Loan Collection of Scientific Apparatus held at South 

 Kensington. There one could see the dynamos of 

 Gramme and Siemens together with the magnetos of 

 the Societe I'Alliance and of Holmes. Trinity House 

 thereupon invited the manufacturers to a trial com- 

 petition to determine the kind of apparatus best 

 suited for the new lighthouse at Lizard Point. The 





1, 





„»; 1, 



:*[]:"Lr 





'2 John Tyndall, "Report on Electric Illumination," Engineer- 

 ing, \611, vol. 24, p. 303; James N. Douglass, "Report on 

 Electric Illumination," Engineering, 1877, vol. 24, pp. 333, 

 351; Richard Higgs and John Brittle, "Some Recent Improve- 

 ments in Dynamo-Electric Apparatus," Minutes of Proceedings 

 oj the Institution of Civil Engineers, 1878, vol. 52, pp. 36-98. 



366 



BULLETIN 228: CONTRIBUTIONS FROM THE MUSEUM OF HISTORY AND TECHNOLOGY 



