Friday, May 9, 2008

Reminiscences of an Active Life #4 -- May 9, 2008

Doctor Peter Henri Van Der Weyde was born in Nymegen, Holland in 1813. He went on to live a remarkable life of achievement in the sciences and the arts. He died in America in 1895.

While serving as editor of Manufacturer and Builder Magazine, he wrote many articles, including the ones which gave this blog its name. In 1893 and 1894, he published a 23-part (!) memoir in the same periodical.

Here is the fourth part. He continues his discussion of his career in electrical engineering.

Antonio Pacinotti was an Italian physicist who improved the dynamo. Zénobe Gramme was a Belgian electrical engineer who created the first dynamo useful in industry.

George B Prescott was the first chief electrician of the Western Union Telegraph Company. His nephew, Frank C Prescott, later became a newspaperman, a lawyer, and a Brigadier General in the California Militia. I assume the Mr Field whom Dr Van der Weyde describes was Stephen Dudley Field.

The image comes from the first installment, in the February, 1893 issue.

Part One

Part Two

Part Three

Reminiscences of an Active Life.


From Manufacturer and Builder, Volume XXV, Number 5. May, 1893

Career as an Electrician (continued from p. 88). -- The statement made that the invention of the dynamo was primarily the result of the successive labors of Pacinotti in Italy and Gramme in France, is based on undeniable facts, recorded in the publications of the period in which those eminent investigators lived. These prove that this modern generator of electricity is, in fact, nothing but the electric motor of Pacinotti, which originally was intended to transform an electric current into a motive power, but of which Gramme inverted the function and used it for the transformation of a moving power into an electric current. The electric motor was, therefore, the predecessor, or parent, of the dynamo, which is, in fact, an inverted electric motor; and as any suitable machine of this kind can be put in operation by an electric current of whatever origin, if only sufficiently strong to move it, it is evident that a dynamo current will cause any suitable electric motor to be put in operation. This shows that the statement attributed to one of the foremost electricians, that the greatest invention of modern times is the inversion of the function of the dynamo (which means that when driven by a motive power it would generate motion in another dynamo), which statement has been going around in many electrical publications, is chronologically erroneous, and should read that the greatest invention of twenty years ago has been the inversion of the electric motor into a dynamo. If such a dynamo is sufficiently large and powerful, its current may drive a large number of small motors, at such a low cost that the voltaic batteries have been abandoned as a motive power on a practically useful scale, and are only used where very weak currents are sufficient, such as is the case with electric bells, alarms, for the telephone, private telegraphs, etc.

The latter word reminds me of the active part I took at an early period to advocate the introduction of dynamos for the transmission of telegraphic signals, and of which I wish to leave a record on the pages of the MANUFACTURER AND BUILDER.

In 1872 when the Western Union Telegraph Company was erecting the large building at the corner of Broadway and Dey street, New York, in which they were to move after its completion, as their limited quarters at the corner of Broadway and Cedar street became too narrow (especially in regard to the space necessary for the batteries required, some of which had to be placed in other buildings), I predicted that at the rate the business of this prosperous company was increasing, the new building, spacious as it was, would soon become too small to contain even the batteries needed, wherefore I advised Mr. Prescott, who then was at the head of the company, to substitute a few dozen dynamos to take the place of all the batteries, which were to occupy a whole floor above the operating room. This space could be utilized for other purposes, while I recommended that the dynamos be placed in the cellar and driven by steam power, without causing any vibration in the building, unavoidable in the use of dynamos, as these machines, in order to accomplish what was needed, had to be driven with very great velocity.

At that time the Gramme dynamo, with the Pacinotti continuous winding, was little understood, and only such machines as produced alternating currents, which were brought in the same direction by commutators, were known by the majority of electricians. They produced pulsating currents, utterly unfit for telegraphy; and this was the objection which Mr. Prescott offered against my plan. I assured him that the Gramme dynamo was not subject to this objection; but as, unfortunately, there was not such a dynamo in this country, he told me that he was soon going to Paris, and intended to investigate this matter. On his return, he stated to me that he found the current produced by this class of dynamos was perfectly uniform, a steady flow, like that from voltaic batteries, keeping the most sensitive galvanometer at a fixed declination, which was constant for a constant velocity of revolution, and only increased when the velocity was increased. He stated that he was satisfied that it could be done, but he hesitated to introduce the innovation, and consequently the whole spacious floor over the operating room in the new building was soon overcrowded with gravity batteries.

As I did not suppose that my idea was patentable, because I had neither invented telegraphy nor the dynamo, while the combination of two so well-known principles appeared to me not to be a patentable device, I made no effort in this direction. I soon found, however, that I was mistaken in this opinion, as soon afterward there arrived from California a certain Mr. Field, who had obtained a patent for this very device, and offered to sell his patent to the Western Union Company. He had devised a combination of six Gramme dynamos, one of which he used to magnetize the fields of the five others. This was an old principle which long before had been applied by Ladd in his current generator, in which he used two revolving armatures, one of which served to magnetize the field while the other served to produce the current to be used for the purpose intended.

Mr. Field arrived in New York just at a very favorable time, as the Western Union Company was compelled to increase again the amount of their battery power, and had actually no more room, as the whole extensive floor was full of batteries, and it was found that the only way out of the serious difficulty was to remove a section of the batteries and substitute therefor the six dynamos which could produce more than fifty times as much current as the battery cups they displaced. The result was, of course, a success, and could not be otherwise, as the current of such dynamos is perfectly identical in character with that of voltaic batteries; being much stronger, it had to be reduced by inserting artificial resistances, which at first consisted of platinum wire wound around cylinders of plaster of Paris. This expensive arrangement was, however, later changed to something better and simpler -- namely, incandescent lamps, which offer the important advantage of illuminating the surrounding space, which frequently is a dark cellar, as is now the case in the dynamo room of the Western Union Telegraph Company.

It was said that Mr. Field was paid $100,000 for his patent, but he told me later that he received a far less amount than that; but certain it is that if my advice, given gratuitously several years before, had been followed, it would have saved the Western Union Telegraph Company a considerable sum of money, not to speak of the bad blunder of not following my opinion, given from the first, to place the dynamos in the cellar on a solid foundation, in place of carrying them up, with the power required to drive them, to one of the upper floors of the very tall building. Surely Mr. Field, who superintended their placement, should have known better.

The result was what I had expected -- the whole building was in a continual state of vibration, so that it became utterly unfit to use the delicate instruments required to measure resistance, volts, amperes, etc., and the company was compelled to hire part of another building, for which some rooms over the store now occupied by Greeley in Dey street, opposite the Western Union building, were selected; connecting wires were stretched across Dey street to one of the upper floors of this building. I saw them in use when I had the pleasure of becoming acquainted with the nephew of Mr. Prescott, who had charge of this department. I found him to be a very intelligent, capable and obliging young gentleman, who took pleasure in showing and explaining to me the beautiful apparatus which the company had provided for the purpose of the measurements required to be taken, such as the resistance of the insulating covering of parts of submarine cables in megohms, as well as the static charge of which the inside conductor of a cable was capable, and which required the most delicate devices which have been invented for that purpose.

As might have been expected, it was not long afterward that the dynamos were removed to the cellar, where the steam power was close at hand, While the voltaic batteries on the upper floor were only used for short distances, such as local messages, etc., some of which, however, were soon displaced by pneumatic tubes connecting the main building directly with branch offices in New York city.

Since the great fire which nearly destroyed the building, all batteries have been discarded and a number of small dynamos substituted for all the work, so that at present there are not any voltaic batteries in use by the company, but every current needed is supplied by dynamos.

(To be Continued).

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