further. In 1876 a smaller and lighter version of the 

 type d' atelier generator appeared that weighed 180 kg. 

 and measured 0.60 meter high, 0.35 meter wide, 

 and 0.65 meter long (fig. 68).^' There were 28 kg. of 

 copper wire on the electromagnets and 4.5 kg. on the 

 armature. When driven by a 2-hp. motor at 820 

 r.p.m. the generator would produce 200 Carcel 

 units; when driven by a 3-hp. motor at 920 r.p.m. 

 it would produce 400 Carcel units. Another model 

 was brought out in 1877 (figs. 69, 70). 



Table 2 gives the values claimed by the French 

 manufacturer for three of the type d'atelier models in 

 January 1879 (fig. 7\).^^ 



Both C and D models had dedonble armatures, so 

 that the two halves of the generator could be connected 



in quantity (parallel) or in tension (series). In the 

 tabulation, C(T) refers to model C connected in 

 tension, D(Q,) to model D connected in quantity, 

 and A(2) to two model A generators. For some 

 reason, the manufacturer gave the light intensity 

 for model A in candles and for models C and D in 

 Carcel units. 



By his later improvements Gramme had converted 

 the electric generator from a laboratory curiosity or 

 an awkward magnetoelectric machine into a fully 

 practical dynamo, ready for commercial exploitation. 

 In 1874, four Gramme generators were sold; by 1875, 

 12 had been sold; by 1876, 85; by 1877, 350; by the 

 middle of 1878, 500; and by 1879, over 1,000. 

 Mechanically, the Gramme dynamo was efficient, 





Price 



Length-width-height 



Weight 











Model 



(£) 



(inches) 



(lbs.) 



R.p.m. 



Hp. 



Light 



CP/H 



A- 



80 



27>i.x 15^^x22^4 



407 



900 



2.5 



6300 



2400 



A (2) 



160 



39 X 19>2 X 153/4 



748 



900 



5.0 



14000 



2800 



C(Q) 



240 



29 X 21K X 25>-2 



858 



1250 



8.0 



2500 



310 



C(T) 



211 



29 X 21K X 25K 



858 



700 



5.0 



1500 



300 



D(Q) 



360 



371,!; X 31/2 X 331,4 



2200 



550 



12.0 



4000 



300 



D(T) 



360 



3714 X 3 IK' X 33K 



2200 



300 



7.0 



2000 



290 



compact, and durable; electrically, unlike previous 

 dynamos, it produced a relatively constant output 

 that was greater than that of any previous one, 

 except possibly the Siemens machine. Although the 

 efficiency seems to have ranged between 80 and 90 

 percent and the main application, until the end of 

 the 1870's, was in the electrochemical industries, 

 the electric light and even the transmission of power 

 was now a possibility.'^ 



A short time after the commercial appearance of 

 these new dynamos, the world of inventors discovered 



" Z. T. Gramme, "Recherche sur Femploi des machines 

 magneto-electriques a courants continus," Comptes rendiis, 1877, 

 vol. 84, pp. 1386-1389; Hippolyte Fontaine, "Eclairage a 

 relectricite," Revue industrielle, 1877, vol. 6, pp. 173-174; 

 1878, vol. 7, pp. 248-250; op. cit. (footnote 12), passim; Engi- 

 neering, 1879, vol. 28, p. 64. 



98 Douglass, op. cit. (footnote 36), p. 129. 



»9 Fontaine, op. cit. (footnote 12), p. 89; Engineering, 1878, 

 vol. 25, p. 526; M. Mascart, "Sur les Machines magneto- 

 electriques," Journal de physique, \^11 , vol. 6, pp. 203-212, 

 297-305; 1878, vol. 7, pp. 79-92, 363-377; Felix Auerbach and 

 O. E. Meyer, "Ueber die Strome der Gramme'schen Mas- 

 chine," Annalen der Physik und Chemie, 1879, vol. 8, pp. 494-514; 

 1880, vol. 9, pp. 676-679; E. Hospitaller, "Sur le Rendement 

 electrique des machines gramme," La Lumiere electrique, 1879, 

 vol. 1, pp. 114-117. 



that such generators could be used as electric motors. 

 This was not a new principle; it had been latent, if 

 not explicit, in all the previous work on generators and 

 motors. Gramme had even noted this in his 1870 

 patent. However, it was a relatively new theory 

 that a dynamo could be so used, and it was soon found 

 that a better motor than ever before could be produced. 

 The usual story is that the discovery was an accidental 

 one — one of the \vorkers at the Vienna Exhibition of 

 1873 happened to connect two Gramme dynamos 

 together and found that one generator could drive 

 the other as an electric motor. Hippolyte Fontaine 

 promptly made such an arrangement part of the 

 Gramme exhibit. A centrifugal pump was driven 

 by a Gramme motor that received its power from a 

 Gramme dynamo three-quarters of a mile away; 

 the pump, in turn, supplied a small waterfall (fig. 73). 

 Fontaine was prompt in publicizing his finding that 

 1 hp. could be transmitted over wires in this manner 

 with an efficiency of about 50 percent. At the 

 Philadelphia Centennial Exposition of 1876, Gramme 

 dynamos were shown running arc lamps, electro- 

 plating, and driving another Gramme dynamo as a 

 motor; and by 1879 Fontaine could assert for this 

 process an over-all efficiency of about 63 percent 



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



385 



