4 GENERAL INTRODUCTION 



Mississippi River at Minneapolis (1857), were largely devoted to 

 the manufacture of flour. 



In 1861 the development of the mighty power of Niagara Falls 

 was begun, a canal being built through the town to a power- 

 house at the edge of the gorge below the falls. The Niagara Falls 

 Hydraulic Power & Manufacturing Company was formed in 

 1872, and during the first years its operation consisted in fur- 

 nishing water to numerous water wheels of different manufactur- 

 ing enterprises. The inefficiency of this method, however, soon 

 became apparent, and a central power-house was built in 1881, 

 the energy being transmitted to the factories along the edge of the 

 cliff by means of ropes, belts and shafts. 



Different opinions exist as to the time at which the first trans- 

 mission of electricity took place. Its possibility was pointed 

 out as early as 1850 and possibly earlier, and it is claimed that in 

 1858 electricity was, for the first time, utilized for driving a com- 

 mercial machine. This was in the artillery works of St. Thomas 

 d'Aquin, France, where a dividing machine was driven by an 

 electric motor, which derived its current from an adjacent bat- 

 tery. Though the electric motor existed long before the dynamo, 

 it attained no prominence until after the practical demonstration 

 of the latter. As long as the galvanic battery constituted the 

 source of power, the application was naturally restricted. Another 

 reason was the defective construction of the earlier motors, their 

 counter E.M.F. being comparatively weak, and hence the work 

 which could be obtained from them was small in comparison with 

 the power expended and their size. 



While the principle of the reversibility of the electric motor 

 seems to have been known as early as 1850, it was the practical 

 experiments carried out by Gramme at the Vienna Exposition in 

 1873 that clearly demonstrated the practical importance of this 

 property. Gramme is, therefore, generally given the credit as 

 being the one who first practically demonstrated the possibility 

 of employing the electric current for transmitting energy from one 

 place to another. His experiments at this Exposition consisted 

 in transmitting current from a machine working as a generator 

 to a second machine about 550 yards distant, working as a 

 motor driving a pump. 



In 1878 a motor was installed at the sugar works at Sermaize, 

 France. It was used to operate a hoist and derived its current 



