cleverness. Tom, indeed, was of opinion that Maggie was

Although Edison had instituted such a costly and exhaustive search throughout the world for the most perfect of natural fibres, he did not necessarily feel committed for all time to the exclusive use of that material for his lamp filaments. While these explorations were in progress, as indeed long before, he had given much thought to the production of some artificial compound that would embrace not only the required homogeneity, but also many other qualifications necessary for the manufacture of an improved type of lamp which had become desirable by reason of the rapid adoption of his lighting system.

At the very time Mr. McGowan was making his explorations deep in South America, and Mr. Ricalton his swift trip around the world, Edison, after much investigation and experiment, had produced a compound which promised better results than bamboo fibres. After some changes dictated by experience, this artificial filament was adopted in the manufacture of lamps. No radical change was immediately made, however, but the product of the lamp factory was gradually changed over, during the course of a few years, from the use of bamboo to the "squirted" filament, as the new material was called. An artificial compound of one kind or another has indeed been universally adopted for the purpose by all manufacturers; hence the incandescing conductors in all carbon-filament lamps of the present day are made in that way. The fact remains, however, that for nearly nine years all Edison lamps (many millions in the aggregate) were made with bamboo filaments, and many of them for several years after that, until bamboo was finally abandoned in the early nineties, except for use in a few special types which were so made until about the end of 1908. The last few years have witnessed a remarkable advance in the manufacture of incandescent lamps in the substitution of metallic filaments for those of carbon. It will be remembered that many of the earlier experiments were based on the use of strips of platinum; while other rare metals were the subject of casual trial. No real success was attained in that direction, and for many years the carbon-filament lamp reigned supreme. During the last four or five years lamps with filaments made from tantalum and tungsten have been produced and placed on the market with great success, and are now largely used. Their price is still very high, however, as compared with that of the carbon lamp, which has been vastly improved in methods of construction, and whose average price of fifteen cents is only one-tenth of what it was when Edison first brought it out.

With the close of Mr. McGowan's and Mr. Ricalton's expeditions, there ended the historic world-hunt for natural fibres. From start to finish the investigations and searches made by Edison himself, and carried on by others under his direction, are remarkable not only from the fact that they entailed a total expenditure of about $100,000, (disbursed under his supervision by Mr. Upton), but also because of their unique inception and thoroughness they illustrate one of the strongest traits of his character--an invincible determination to leave no stone unturned to acquire that which he believes to be in existence, and which, when found, will answer the purpose that he has in mind.

INVENTING A COMPLETE SYSTEM OF LIGHTING

IN Berlin, on December 11, 1908, with notable eclat, the seventieth birthday was celebrated of Emil Rathenau, the founder of the great Allgemein Elektricitaets Gesellschaft. This distinguished German, creator of a splendid industry, then received the congratulations of his fellow-countrymen, headed by Emperor William, who spoke enthusiastically of his services to electro-technics and to Germany. In his interesting acknowledgment, Mr. Rathenau told how he went to Paris in 1881, and at the electrical exhibition there saw the display of Edison's inventions in electric lighting "which have met with as little proper appreciation as his countless innovations in connection with telegraphy, telephony, and the entire electrical industry." He saw the Edison dynamo, and he saw the incandescent lamp, "of which millions have been manufactured since that day without the great master being paid the tribute to his invention." But what impressed the observant, thoroughgoing German was the breadth with which the whole lighting art had been elaborated and perfected, even at that early day. "The Edison system of lighting was as beautifully conceived down to the very details, and as thoroughly worked out as if it had been tested for decades in various towns. Neither sockets, switches, fuses, lamp-holders, nor any of the other accessories necessary to complete the installation were wanting; and the generating of the current, the regulation, the wiring with distributing boxes, house connections, meters, etc., all showed signs of astonishing skill and incomparable genius."

Such praise on such an occasion from the man who introduced incandescent electric lighting into Germany is significant as to the continued appreciation abroad of Mr. Edison's work. If there is one thing modern Germany is proud and jealous of, it is her leadership in electrical engineering and investigation. But with characteristic insight, Mr. Rathenau here placed his finger on the great merit that has often been forgotten. Edison was not simply the inventor of a new lamp and a new dynamo. They were invaluable elements, but far from all that was necessary. His was the mighty achievement of conceiving and executing in all its details an art and an industry absolutely new to the world. Within two years this man completed and made that art available in its essential, fundamental facts, which remain unchanged after thirty years of rapid improvement and widening application.

Such a stupendous feat, whose equal is far to seek anywhere in the history of invention, is worth studying, especially as the task will take us over much new ground and over very little of the territory already covered. Notwithstanding the enormous amount of thought and labor expended on the incandescent lamp problem from the autumn of 1878 to the winter of 1879, it must not be supposed for one moment that Edison's whole endeavor and entire inventive skill had been given to the lamp alone, or the dynamo alone. We have sat through the long watches of the night while Edison brooded on the real solution of the swarming problems. We have gazed anxiously at the steady fingers of the deft and cautious Batchelor, as one fragile filament after another refused to stay intact until it could be sealed into its crystal prison and there glow with light that never was before on land or sea. We have calculated armatures and field coils for the new dynamo with Upton, and held the stakes for Jehl and his fellows at their winding bees. We have seen the mineral and vegetable kingdoms rifled and ransacked for substances that would yield the best "filament." We have had the vague consciousness of assisting at a great development whose evidences to-day on every hand attest its magnitude. We have felt the fierce play of volcanic effort, lifting new continents of opportunity from the infertile sea, without any devastation of pre-existing fields of human toil and harvest. But it still remains to elucidate the actual thing done; to reduce it to concrete data, and in reducing, to unfold its colossal dimensions.

The lighting system that Edison contemplated in this entirely new departure from antecedent methods included the generation of electrical energy, or current, on a very large scale; its distribution throughout extended areas, and its division and subdivision into small units converted into light at innumerable points in every direction from the source of supply, each unit to be independent of every oth- er and susceptible to immediate control by the user.