The First Edison Central Station- 5

The First Edison Central Station- 5

 Into this converted structure was put the most complete steam plant obtainable, together

with all the mechanical and engineering adjuncts bearing upon economical and successful

operation. Being in a narrow street and a congested district, the plant needed special

facilities for the handling of coal and ashes, as well as for ventilation and forced draught.

All of these details received Mr. Edison's personal care and consideration on the spot, in

addition to the multitude of other affairs demanding his thought. Although not a steam or

mechanical engineer, his quick grasp of principles and omnivorous reading had soon

supplied the lack of training; nor had he forgotten the practical experience picked up as a

boy on the locomotives of the Grand Trunk road. It is to be noticed as a feature of the

plant, in common with many of later construction, that it was placed well away from the

water's edge, and equipped with non-condensing engines; whereas the modern plant

invariably seeks the bank of a river or lake for the purpose of a generous supply of water

for its condensing engines or steam-turbines. These are among the refinements of practice

coincidental with the advance of the art.

At the award of the John Fritz gold medal in April, 1909, to Charles T. Porter for his

work in advancing the knowledge of steam-engineering, and for improvements in engine

construction, Mr. Frank J. Sprague spoke on behalf of the American Institute of Electrical

Engineers of the debt of electricity to the high-speed steam-engine. He recalled the fact

that at the French Exposition of 1867 Mr. Porter installed two Porter-Allen engines to

drive electric alternating-current generators for supplying current to primitive lighthouse

apparatus. While the engines were not directly coupled to the dynamos, it was a curious

fact that the piston speeds and number of revolutions were what is common to-day in

isolated direct-coupled plants. In the dozen years following Mr. Porter built many engines

with certain common characteristics-- i.e., high piston speed and revolutions, solid engine

bed, and babbitt-metal bearings; but there was no electric driving until 1880, when Mr.

Porter installed a high-speed engine for Edison at his laboratory in Menlo Park. Shortly

after this he was invited to construct for the Edison Pearl Street station the first of a series

of engines for so-called "steam-dynamos," each independently driven by a direct-coupled

engine. Mr. Sprague compared the relations thus established between electricity and the

high-speed engine not to those of debtor and creditor, but rather to those of partners--an

industrial marriage--one of the most important in the engineering world. Here were two

machines destined to be joined together, economizing space, enhancing economy,

augmenting capacity, reducing investment, and increasing dividends.

While rapid progress was being made in this and other directions, the wheels of industry

were hum- ming merrily at the Edison Tube Works, for over fifteen miles of tube

conductors were required for the district, besides the boxes to connect the network at the

street intersections, and the hundreds of junction boxes for taking the service conductors

into each of the hundreds of buildings. In addition to the immense amount of money

involved, this specialized industry required an enormous amount of experiment, as it

called for the development of an entirely new art. But with Edison's inventive fertility--if

ever there was a cross-fertilizer of mechanical ideas it is he--and with Mr. Kruesi's neverfailing

patience and perseverance applied to experiment and evolution, rapid progress

was made. A franchise having been obtained from the city, the work of laying the

underground conductors began in the late fall of 1881, and was pushed with almost

frantic energy. It is not to be supposed, however, that the Edison tube system had then

reached a finality of perfection in the eyes of its inventor. In his correspondence with

Kruesi, as late as 1887, we find Edison bewailing the inadequacy of the insulation of the

conductors under twelve hundred volts pressure, as for example: "Dear Kruesi,--There is

nothing wrong with your present compound. It is splendid. The whole trouble is airbubbles.

The hotter it is poured the greater the amount of air-bubbles. At 212 it can be put

on rods and there is no bubble. I have a man experimenting and testing all the time. Until

I get at the proper method of pouring and getting rid of the air-bubbles, it will be waste of

time to experiment with other asphalts. Resin oil distils off easily. It may answer, but

paraffine or other similar substances must be put in to prevent brittleness, One thing is

certain, and that is, everything must be poured in layers, not only the boxes, but the tubes.

The tube itself should have a thin coating. The rope should also have a coating. The rods

also. The whole lot, rods and rope, when ready for tube, should have another coat, and

then be placed in tube and filled. This will do the business." Broad and large as a

continent in his ideas, if ever there was a man of finical fussiness in attention to detail, it

is Edison. A letter of seven pages of about the same date in 1887 expatiates on the vicious

troubles caused by the air-bubble, and remarks with fine insight into the problems of

insulation and the idea of layers of it: "Thus you have three separate coatings, and it is

impossible an air-hole in one should match the other."