Sunday, March 9, 2008

Reminiscences of an Active Life #2 -- March 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 second part. He discusses his early studies of electricity.

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

Part One

Reminiscences of an Active Life.


From Manufacturer and Builder, Volume XXV, Number 3. March, 1893

Career as an Electrician (continued from p. 26). -- It is evident that the favorable reputation which was obtained for electric medical treatment was largely due to the circumstance that it was applied to men who had previously been overdosed with drugs, and whose digestive organs I left to nature. The result was that all the veterans wanted to take part in the electric treatment, so that I soon had the whole regiment at my disposal. This exactly suited me, and I considered myself fully as fortunate as the Abbé Nollet, one hundred years before, when he obtained, by order of the King of France, a whole regiment of soldiers to experiment upon with the then newly-invented electric appliances. In the same way the men were to me objects to experiment upon, and my experiments were made in various ways, such as insulating the one who supposed that he needed electric treatment most, keeping him charged by permanent connection with the prime conductor, while the electric machine was kept in motion, and letting the regiment pass by, every man in his turn drawing sparks from such parts of the charged man, and by such parts of the bodies of the passing column, as were supposed to need repair.

I remember vividly one man with an anchylosed knee joint, who claimed, after every treatment, that he could bend his knee a little more, while in fact I could detect no difference. Such is faith.

The reputation of the electric treatment spread also outside the barracks, and many others applied for the privilege of being charged, sparked or shocked. I accommodated them, as I was continually learning something by varying my experiments; so, in this sense, it did me a great deal of good, but I doubted if it did any good to the patients, and therefore I never charged anything. At that time I was not yet graduated as an M. D., and not entitled to the rights of doctors, who always charge whether they cure or not, and who also charge even when they kill the patient, of which quite recently I have been informed of a sad example.

All the experiments here mentioned were made with friction electric machines, either with a glass disk or the cylinder machine which I had made from a large bottle, as before described. In the meantime I continued my experiments with the voltaic pile, and, for the sake of chronological order, must mention that an attempt to verify Oersted’s fundamental experiment revealing the relation between electricity and magnetism, was made long before trying the two liquids suggested by Berzelius in 1833, and referred to on page 26 of the February issue of this journal.

I heard of this discovery of Oersted about the year 1829, in listening to a conversation between my father and Gen. Krayenhoff, who was an eminent physicist, had his large house filled with physical apparatus, enjoyed a pension, and at the age of between 70 and 80 found his greatest pleasure in physical research. He gave a lecture on physics every Thursday evening at his house, to which the physicians, druggists and principal school teachers of the city were admitted. As I was neither the one nor the other, I attended these lectures by special favor through his friendship to my father, and was the only boy among that audience.

Oersted’s fundamental experiment consists, as is well known, in the practical demonstration that a compass needle will always place itself at a right angle to the wire conducting the current. My first attempt to verify it was made with a current strong enough to pass a shock through a whole regiment of veterans, provided the weather was extra dry, but it failed. I soon commenced to understand that static electricity gives no flow of current like voltaic, and then applied the voltaic pile; this also failed, even after the column was cleaned and freshly re-erected. Then I took the liberty of calling on the kind old general, who smiled, and told me to follow him and he would show me. He conducted me to a room labeled “Electro-Magnetism,” and took a zinc plate about two feet square and placed it in a narrow copper trough of a little larger dimensions, lined with wooden strips so as to prevent metallic contact. It contained diluted sulphuric acid. Then he connected the copper and the zinc by means of two pieces of copper wire with the two ends of a strip of sheet copper placed under a compass needle and parallel to that needle, and the needle obeyed.

This, in combination with my own experiments, was my first lesson in what at present we call amperes and volts. The voltaic column has plenty of voltage, or pressure, but very little current, or amperes, and the deficiency of these was the cause of my failure. I understood then fully that the quantity of current increased with the size of the plates, while the pressure increased in the ratio of their number when connected in series, which means copper, zinc; copper, zinc, etc.; while their connection in parallel -- which means all the coppers joined, and also all the zincs -- makes the battery equivalent to one single cell of large size. I followed the method thus described, which was to discard the laborious and ineffective voltaic piles, and use instead cups containing the plates and the acids, which resulted in a complete revolution of electrical methods and in the results obtained.

It was not long after these experiments that the important discovery of Oersted began to bear fruit. It led, in less than ten years, to the invention of the electro-magnet by Sturgeon, and in a very few years more to its application for transmitting signals over long wires(electric telegraphy). It was exactly twenty years after Oersted's discovery that Morse obtained his patent for the electric telegraph (1840), which began to be put in practice four years later, and has during the succeeding half century grown to the most gigantic proportions.

The utilization of the electric current for mechanical purposes did not grow so rapidly, for the reason that, while for the transmission of signals a very feeble current is sufficient, for mechanical purposes a very strong current is required, in order to make the power obtained of practical utility. Of this fact my personal experience satisfied me at an early period. An account of this experience is added here, by reason of its usefulness and its bearing upon later improvements.

A great stimulus was given to experimenters in this line, when, in 1837, the newspapers announced that Jacobi, in St. Petersburg, was experimenting to propel a boat on the Neva by means of an electric engine. The stimulus was increased by a resolution of the representatives of the German Bund, assembled in Frankfort-on-the-Main, promising a premium of several thousand thalers to the inventor who would produce an electric motor capable of superseding the steam engine.

The text of their resolution is quite a curiosity when looked at in the light of our present knowledge of electricity. It should be considered that at that time the dynamo had not yet been invented, and, being utterly unknown, the only generators of electric currents were voltaic batteries. An abstract of their program ran about thus:

“Considering the serious calamities and frequent loss of life incident to the use of steam power, and the mildness and consequent safety of electric currents, it will be of great importance to supersede those dangerous engines and boilers by the safe electro-motors. Therefore the Bundestag has voted a premium of a hundred thousand thalers to electricians of any nationality who will invent and exhibit an electro-motor performing the functions of a steam engine.”

No wonder that many electricians went to work to make the desired practical electro-motor, and that the writer was one of them. Having then a good workshop, with all the conveniences needed, he began at once. The first question was: Which will be the most available construction? To bring this to a practical test, I made a series of some thirty or forty small working models, all of the same size, but of different construction, as well in principles as in details. The size was, on the average, 10 by 7 inches, the hight varied from 4 to 10, and even 12 inches. In most of them the axis of rotation was vertical, for convenience of construction, the intention being to test which of them could be moved with the smallest battery, and to select that which satisfied this test, and then build it on a large scale.

This was done. Six large electro-magnets of soft iron, horseshoe form, and some 40 pounds weight each, were furnished with proper coils (made of strips of sheet copper, as at that time only brass wire, and no copper wire, could be obtained in the trade). This furnished twelve poles, of which six were made stationary, while the other six revolved in front of them on a horizontal axis. This furnished a fly-wheel of some 150 pounds, and by means of a pulley and belt ran the lathe by means of a voltaic battery of six cups, provided that no work was done; but when it was attempted to turn a simple piece of wood, the application of the chisel stopped the rotation, and it was evident that more current was needed, so the battery was doubled to twelve cups. This was an improvement on the others, but was not quite satisfactory, and twelve more cups were added, making it a battery of twenty-four cups. This, however, involved so much labor to attend to the cleaning, etc., of the battery, that a man was hired to attend to this; a number of extra cups was furnished to substitute for such as needed renovation, so that the man was continually kept busy while the turner attended to the work at the lathe.

(To be Continued)

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