In the early part of 1888an arrangement was made with the Westinghouse Company for the manufacture of the motors on a large scale.But great difficulties had still to be overcome.My system was based on the use of low frequency currents and the Westinghouse experts had adopted 133cycles with the object of securing advantages in the transformation.They did not want to depart from their standard forms of apparatus and my efforts had to be concentrated upon adapting the motor to these conditions.Another necessity was to produce a motor capable of running efficiently at this frequency on two wires which was not easy of accomplishment.
At the close of 1889,however,my services in Pittsburg being no longer essential,Ireturned to New York and resumed experimental work in a laboratory on Grand Street,where Ibegan immediately the design of high frequency machines.The problems of construction in this unexplored field were novel and quite peculiar and Iencountered many difficulties.Irejected the inductor type,fearing that it might not yield perfect sine waves which were so important to resonant action.Had it not been for this Icould have saved myself a great deal of labor.Another discouraging feature of the high frequency alternator seemed to be the inconstancy of speed which threatened to impose serious limitations to its use.Ihad already noted in my demonstrations before the American Institution of Electrical Engineers that several times the tune was lost,necessitating readjustment,and did not yet foresee,what Idiscovered long afterwards,a means of operating a machine of this kind at a speed constant to such a degree as not to vary more than a small fraction of one revolution between the extremes of load.
From many other considerations it appeared desirable to invent a ******r device for the production of electric oscillations.In 1856Lord Kelvin had exposed the theory of the condenser discharge,but no practical application of that important knowledge was made.Isaw the possibilities and undertook the development of induction apparatus on this principle.My progress was so rapid as to enable me to exhibit at my lecture in 1891a coil giving sparks of five inches.On that occasion Ifrankly told the engineers of a defect involved in the transformation by the new method,namely,the loss in the spark gap.Subsequent investigation showed that no matter what medium is employed,be it air,hydrogen,mercury vapor,oil or a stream of electrons,the efficiency is the same.It is a law very much like that governing the conversion of mechanical energy.We may drop a weight from a certain height vertically down or carry it to the lower level along any devious path,it is immaterial insofar as the amount of work is concerned.Fortunately however,this drawback is not fatal as by proper proportioning of the resonant circuits an efficiency of 85per cent is attainable.Since my early announcement of the invention it has come into universal use and wrought a revolution in many departments.But a still greater future awaits it.
When in 1900Iobtained powerful discharges of 100feet and flashed a current around the globe,Iwas reminded of the first tiny spark Iobserved in my Grand Street laboratory and was thrilled by sensations akin to those Ifelt when Idiscovered the rotating magnetic field.
