But, as the reader has already learned, the metallic filament was soon laid aside in favor of carbon, and we find in the laboratory notes an amazing record of research and experiment conducted in the minute and searching manner peculiar to Edison's method. His inquiries were directed along all the various roads leading to the desired goal, for long before he had completed the invention of a practical lamp he realized broadly the fundamental requirements of a successful system of electrical distribution, and had given instructions for the making of a great variety of calculations which, although far in advance of the time, were clearly foreseen by him to be vitally important in the ultimate solution of the complicated problem. Thus we find many hundreds of pages of the note-books covered with computations and calculations by Mr. Upton, not only on the numerous ramifications of the projected system and comparisons with gas, but also on proposed forms of dynamos and the proposed station in New York. A mere recital by titles of the vast number of experiments and tests on carbons, lamps, dynamos, armatures, commutators, windings, systems, regulators, sockets, vacuum-pumps, and the thousand and one details relating to the subject in general, originated by Edison, and methodically and systematically carried on under his general direction, would fill a great many pages here, and even then would serve only to convey a confused impression of ceaseless probing.
It is possible only to a broad, comprehensive mind well stored with knowledge, and backed with resistless, boundless energy, that such a diversified series of experiments and investigations could be carried on simultaneously and assimilated, even though they should relate to a class of phenomena already understood and well defined. But if we pause to consider that the commercial subdivision of the electric current (which was virtually an invention made to order) involved the solution of problems so unprecedented that even they themselves had to be created, we cannot but conclude that the afflatus of innate genius played an important part in the unique methods of investigation instituted by Edison at that and other times.
The idea of attributing great successes to "genius" has always been repudiated by Edison, as evidenced by his historic remark that "Genius is 1 per cent. inspiration and 99 per cent. perspiration." Again, in a conversation many years ago at the laboratory between Edison, Batchelor, and E. H. Johnson, the latter made allusion to Edison's genius as evidenced by some of his achievements, when Edison replied:
"Stuff! I tell you genius is hard work, stick-to-it-iveness, and common sense."
"Yes," said Johnson, "I admit there is all that to it, but there's still more. Batch and I have those qualifications, but although we knew quite a lot about telephones, and worked hard, we couldn't invent a brand-new non-infringing telephone receiver as you did when Gouraud cabled for one. Then, how about the subdivision of the electric light?"
"Electric current," corrected Edison.
"True," continued Johnson; "you were the one to make that very distinction. The scientific world had been working hard on subdivision for years, using what appeared to be common sense. Results worse than nil. Then you come along, and about the first thing you do, after looking the ground over, is to start off in the opposite direction, which subsequently proves to be the only possible way to reach the goal. It seems to me that this is pretty close to the dictionary definition of genius."
It is said that Edison replied rather incoherently and changed the topic of conversation.
This innate modesty, however, does not prevent Edison from recognizing and classifying his own methods of investigation. In a conversation with two old associates recently (April, 1909), he remarked: "It has been said of me that my methods are empirical. That is true only so far as chemistry is concerned. Did you ever realize that practically all industrial chemistry is colloidal in its nature? Hard rubber, celluloid, glass, soap, paper, and lots of others, all have to deal with amorphous substances, as to which comparatively little has been really settled. My methods are similar to those followed by Luther Burbank. He plants an acre, and when this is in bloom he inspects it. He has a sharp eye, and can pick out of thousands a single plant that has promise of what he wants. From this he gets the seed, and uses his skill and knowledge in producing from it a number of new plants which, on development, furnish the means of propagating an improved variety in large quantity. So, when I am after a chemical result that I have in mind, I may make hundreds or thousands of experiments out of which there may be one that promises results in the right direction. This I follow up to its legitimate conclusion, discarding the others, and usually get what I am after. There is no doubt about this being empirical; but when it comes to problems of a mechanical nature, I want to tell you that all I've ever tackled and solved have been done by hard, logical thinking." The intense earnestness and emphasis with which this was said were very impressive to the auditors. This empirical method may perhaps be better illustrated by a specific example. During the latter part of the storage battery investigations, after the form of positive element had been determined upon, it became necessary to ascertain what definite proportions and what quality of nickel hydrate and nickel flake would give the best results. A series of positive tubes were filled with the two materials in different proportions—say, nine parts hydrate to one of flake; eight parts hydrate to two of flake; seven parts hydrate to three of flake, and so on through varying proportions. Three sets of each of these positives were made, and all put into separate test tubes with a uniform type of negative element. These were carried through a long series of charges and discharges under strict test conditions. From the tabulated results of hundreds of tests there were selected three that showed the best results. These, however, showed only the superiority of certain PROPORTIONS of the materials. The next step would be to find out the best QUALITY. Now, as there are several hundred variations in the quality of nickel flake, and perhaps a thousand ways to make the hydrate, it will be realized that Edison's methods led to stupendous detail, for these tests embraced a trial of all the qualities of both materials in the three proportions found to be most suitable. Among these many thousands of experiments any that showed extraordinary results were again elaborated by still further series of tests, until Edison was satisfied that he had obtained the best result in that particular line.
The laboratory note-books do not always tell the whole story or meaning of an experiment that may be briefly outlined on one of their pages. For example, the early filament made of a mixture of lampblack and tar is merely a suggestion in the notes, but its making afforded an example of Edison's pertinacity. These materials, when mixed, became a friable mass, which he had found could be brought into such a cohesive, putty-like state by manipulation, as to be capable of being rolled out into filaments as fine as seven-thousandths of an inch in cross-section. One of the laboratory assistants was told to make some of this mixture, knead it, and roll some filaments. After a time he brought the mass to Edison, and said: