Figure 74. — The Siemens and Halske alternator 

 with external exciter, as shown in Vienna 

 Exhibition of 1873. From A. Thomalen, 

 "Zur Geschichte der Dynamomaschine," 

 Beitrdge z.ur Geschichte der Technik und Industrie, 

 1916, vol. 7, p. 149. 



Figure 75. — The Siemens and Halske dynamo 

 of 1876. Fronn J. Dredge, Electric Illumina- 

 tion. London, n.d. (about 1882), vol. i, p. 

 280. 



Table 4. — Shoolbred's comparison of three models of the Siemens machine and three models of the Gramme 



type d'atelier, 1878. 



Machine and modei 



R.p.m. 



Candles 



Hp. to 

 drive 



Candles! 

 Hp. 



Weight 



Cost{£) 



Siemens, Model A 



850 



1200 



2 



600 



250 



70 



Siemens, Model B 



650 



6000 



4 



1500 



375 



112 



Siemens, Model C 



360 



14000 



8 



1750 



1150 



250 



Gramme, Model M 



1600 



2000 



1.5 



1333 



150 



70 



Gramme, Model A 



900 



6000 



2.5 



2400 



375 



100 



Gramme, Model C 



700 



15000 



5 



3000 



800 



300 



Table ^.—Evaluation of the Siemens and Gramme dynamos at Chatham, England, in iSyg. 



Machine and model 



R.p.m. 



Candles 



Hp. to 



drive 



CandleslHp. 



Cost Efficiency 

 (£) (%) 



Siemens, Model B, two 



680 



19140 



13.4 



1430 



244 73 



Gramme, Model A, two 



875 



18300 



9.6 



1920 



160 88 



Gramme, Model C 



1200 



19500 



9.5 



2050 



240 85 



Gramme, Model D 



500 



27500 



15. 1 



1820 



360 89 



Gramme, Model D 



475 



22500 



12:7 



1770 



360 88 



PAPER 30: DEVELOPMENT OF ELECTRICAL TECHNOLOGY IN THE 19TH CENTURY: III 



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