Edison: His Life and Inventions

by Frank Lewis Dyer; Thomas Commerford Martin

A keen appreciation of ultimate success in the production of a fine quality of cement led Edison to provide very carefully in his original scheme for those details that he foresaw would become requisite—such, for instance, as ample stock capacity for raw materials and their automatic delivery in the various stages of manufacture, as well as mixing, weighing, and frequent sampling and analyzing during the progress through the mills. This provision even included the details of the packing-house, and his perspicacity in this case is well sustained from the fact that nine years afterward, in anticipation of building an additional packing-house, the company sent a representative to different parts of the country to examine the systems used by manufacturers in the packing of large quantities of various staple commodities involving somewhat similar problems, and found that there was none better than that devised before the cement plant was started. Hence, the order was given to build the new packing-house on lines similar to those of the old one.

Among the many innovations appearing in this plant are two that stand out in bold relief as indicating the large scale by which Edison measures his ideas. One of these consists of the crushing and grinding machinery, and the other of the long kilns. In the preceding chapter there has been given a description of the giant rolls, by means of which great masses of rock, of which individual pieces may weigh eight or more tons, are broken and reduced to about a fourteen-inch size. The economy of this is apparent when it is considered that in other cement plants the limit of crushing ability is "one-man size"—that is, pieces not too large for one man to lift.

The story of the kiln, as told by Mr. Mallory, is illustrative of Edison's tendency to upset tradition and make a radical departure from generally accepted ideas. "When Mr. Edison first decided to go into the cement business, it was on the basis of his crushing-rolls and air separation, and he had every expectation of installing duplicates of the kilns which were then in common use for burning cement. These kilns were usually made of boiler iron, riveted, and were about sixty feet long and six feet in diameter, and had a capacity of about two hundred barrels of cement clinker in twenty-four hours.

"When the detail plans for our plant were being drawn, Mr. Edison and I figured over the coal capacity and coal economy of the sixty-foot kiln, and each time thought that both could he materially bettered. After having gone over this matter several times, he said: 'I believe I can make a kiln which will give an output of one thousand barrels in twenty-four hours.' Although I had then been closely associated with him for ten years and was accustomed to see him accomplish great things, I could not help feeling the improbability of his being able to jump into an old-established industry—as a novice—and start by improving the 'heart' of the production so as to increase its capacity 400 per cent. When I pressed him for an explanation, he was unable to give any definite reasons, except that he felt positive it could be done. In this connection let me say that very many times I have heard Mr. Edison make predictions as to what a certain mechanical device ought to do in the way of output and costs, when his statements did not seem to be even among the possibilities. Subsequently, after more or less experience, these predictions have been verified, and I cannot help coming to the conclusion that he has a faculty, not possessed by the average mortal, of intuitively and correctly sizing up mechanical and commercial possibilities.

"But, returning to the kiln, Mr. Edison went to work immediately and very soon completed the design of a new type which was to be one hundred and fifty feet long and nine feet in diameter, made up in ten-foot sections of cast iron bolted together and arranged to be revolved on fifteen bearings. He had a wooden model made and studied it very carefully, through a series of experiments. These resulted so satisfactorily that this form was finally decided upon, and ultimately installed as part of the plant.

"Well, for a year or so the kiln problem was a nightmare to me. When we started up the plant experimentally, and the long kiln was first put in operation, an output of about four hundred barrels in twenty-four hours was obtained. Mr. Edison was more than disappointed at this result. His terse comment on my report was: 'Rotten. Try it again.' When we became a little more familiar with the operation of the kiln we were able to get the output up to about five hundred and fifty barrels, and a little later to six hundred and fifty barrels per day. I would go down to Orange and report with a great deal of satisfaction the increase in output, but Mr. Edison would apparently be very much disappointed, and often said to me that the trouble was not with the kiln, but with our method of operating it; and he would reiterate his first statement that it would make one thousand barrels in twenty-four hours.

"Each time I would return to the plant with the determination to increase the output if possible, and we did increase it to seven hundred and fifty, then to eight hundred and fifty barrels. Every time I reported these increases Mr. Edison would still be disappointed. I said to him several times that if he was so sure the kiln could turn out one thousand barrels in twenty-four hours we would be very glad to have him tell us how to do it, and that we would run it in any way he directed. He replied that he did not know what it was that kept the output down, but he was just as confident as ever that the kiln would make one thousand barrels per day, and that if he had time to work with and watch the kiln it would not take him long to find out the reasons why. He had made a number of suggestions throughout these various trials, however, and, as we continued to operate, we learned additional points in handling, and were able to get the output up to nine hundred barrels, then one thousand, and finally to over eleven hundred barrels per day, thus more than realizing the prediction made by Mr. Edison before even the plans were drawn. It is only fair to say, however, that prolonged experience has led us to the conclusion that the maximum economy in continuous operation of these kilns is obtained by working them at a little less than their maximum capacity.

"It is interesting to note, in connection with the Edison type of kiln, that when the older cement manufacturers first learned of it, they ridiculed the idea universally, and were not slow to predict our early 'finish' as cement manufacturers. The ultimate success of the kiln, however, proved their criticisms to be unwarranted. Once aware of its possibility, some of the cement manufacturers proceeded to avail themselves of the innovation (at first without Mr. Edison's consent), and to-day more than one-half of the Portland cement produced in this country is made in kilns of the Edison type. Old plants are lengthening their kilns wherever practicable, and no wide-awake manufacturer building a modern plant could afford to install other than these long kilns. This invention of Mr. Edison has been recognized by the larger cement manufacturers, and there is every prospect now that the entire trade will take licenses under his kiln patents."

When he decided to go into the cement business, Edison was thoroughly awake to the fact that he was proposing to "butt into" an old-established industry, in which the principal manufacturers were concerns of long standing. He appreciated fully its inherent difficulties, not only in manufacture, but also in the marketing of the product. These considerations, together with his long-settled principle of striving always to make the best, induced him at the outset to study methods of producing the highest quality of product. Thus he was led to originate innovations in processes, some of which have been preserved as trade secrets; but of the others there are two deserving special notice—namely, the accuracy of mixing and the fineness of grinding.

In cement-making, generally speaking, cement rock and limestone in the rough are mixed together in such relative quantities as may be determined upon in advance by chemical analysis. In many plants this mixture is made by barrow or load units, and may be more or less accurate. Rule-of-thumb methods are never acceptable to Edison, and he devised therefore a system of weighing each part of the mixture, so that it would be correct to a pound, and, even at that, made the device "fool-proof," for as he observed to one of his associates: "The man at the scales might get to thinking of the other fellow's best girl, so fifty or a hundred pounds of rock, more or less, wouldn't make much difference to him." The Edison checking plan embraces two hoppers suspended above two platform scales whose beams are electrically connected with a hopper-closing device by means of needles dipping into mercury cups. The scales are set according to the chemist's weighing orders, and the material is fed into the scales from the hoppers. The instant the beam tips, the connection is broken and the feed stops instantly, thus rendering it impossible to introduce any more material until the charge has been unloaded.