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.This situation put definite limits to the amount ofcurrent which could be loaded on to conductors.In addition there is an accompanying drop in pressure.In ahalf-mile-long conductor, of the size adopted and under theaverage currents carried, there would be a drop of about 30volts.To compensate for this, to some extent, the dynamoswere designed to generate 120 volts instead of the standard110 volts for which lamps were designed.Near thepowerhouse the customers would get excess voltage--and ahalf-mile away their current would be delivered at 90volts.The early Edison carbon lamps were none toobrilliant at 110 volts and gave much less than satisfactoryillumination at 90 volts.As a result of this situation the generation anddistribution of direct-electric current became very much ofa localized matter.The Edison powerhouse could serve anarea less than a mile in diameter.In order to give serviceto a large city it would be necessary to have a powerhousein every square mile, or even closer if a uniformlysatisfactory current were to be supplied.Outside largecities the situation became even more dificult.This was asevere handicap if electricity was to become the universalpower source.Tesla's alternating-current power system, which Edison soemphatically rejected when it was offered to him, freedelectricity from its bondage to local isolation.Not alonewere his alternating-current motors more simple andflexible than the direct-current machines, but it waspossible by a highly efficient method of usingtransformers, which consisted of two coils of wire aroundan iron core, to step up the voltage and simultaneouslystep down the current in a proportionate amount, or use theprocess in reverse.The amount of energy involved, however,would remain practically unchanged.Copper wire entails a heavy investment when it is bought bythe mile.The diameter of the wire sets the limit to theamount of current it will carry.With the Edison direct-current system there was no practical way for transformingan electric current.The voltage remained fixed and when61 the current was increased to the carrying capacity of thewire no further expansion was possible on that circuit.With the Tesla system the amount of energy a wire wouldtransport would be increased tremendously by increasing thevoltage and letting the current remain fixed below thecarrying limit of the circuit.A very small wire couldcarry a thousand or more times as much electrical energy inthe Tesla polyphase alternating system as it could in theEdison direct-current system.By using Tesla's alternating-current system electricitycould be delivered economically at vast distances from thepowerhouse.It would be possible, if desired, to burn coalat the mouth of a mine for generating electricity, anddeliver the current cheaply at distant cities, or togenerate electricity where water power was available andtransmit it to distant points where it could be used.Tesla rescued the electrical giant from the apron stringsof the powerhouse and gave it geographical freedom, theopportunity to expand into the wide-open spaces and workits magic.He laid the foundation for our presentsuperpower system.A development of such magnitude wasbound to be loaded with dynamite, and action was sure tofollow as soon as someone set a match to the fuse.TESLA'S spectacular lecture and demonstration before theAmerican Institute of Electrical Engineers in New Yorkfocused on his work the attention of the electricalfraternity throughout the world.There was no doubt in themind of the vast majority of electrical engineers thatTesla's discoveries created a new epoch in the electricalindustry.But what could be done about it? There were fewmanufacturers who could take advantage of it.Hisdiscoveries were in the same predicament as a ten-pounddiamond.No one would question the value of the stone butwho would be in a position to purchase it or make any useof it?62 Tesla had given no specific thought to commercializing hiswork at this time
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