Part 1

Transcriber’s Notes:

Text enclosed by underscores is in italics (_italics_).

The whole number part of a mixed fraction is separated from the fractional part with -, for example, 2-1/2.

Additional Transcriber’s Notes are at the end.

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SØREN HJORTH

SØREN HJORTH

INVENTOR OF THE DYNAMO-ELECTRIC PRINCIPLE

BY

SIGURD SMITH C. E., M. I. F.

PUBLISHED BY »ELEKTROTEKNISK FORENING« AT THE EXPENSE OF THE CARLSBERG FOUNDATION

KØBENHAVN PRINTED BY J. JORGENSEN & CO. (M. A. HANNOVER) 1912

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This pamphlet is published simultaneously in English and in Danish, and is distributed among interested institutions all over the world.

Translated by F. SODEMANN, C. E., M. I. F.

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_Handsworth, Birmingham, Feb. 6th, 1851._

... After this wonderful force has been discovered by Your Excellency, it has been my pride and interest that also the utilization thereof should be originated by a Dane....

(_Fragment of a letter from Hjorth to H. C. Ørsted._)

PREFACE.

Since the Life and Works of Søren Hjorth, the Dane was published in the Danish technical journal the »Elektroteknikeren«, in 1907, a statement concerning Hjorth’s rights of priority to the invention of the dynamo-electric principle has been sent to the leading foreign technical periodicals, viz. »Elektrotechnische Zeitschrift«, »L’éclairage électrique«, and »Electrical Engineering«. As this statement still stands uncontradicted, it seems reasonable to consider Hjorth’s priority rights to this principle to be generally acknowledged, even in the great centres of civilization. Therefore I highly appreciated the courtesy of Mr. Hjorth’s heirs, after the death of his step-daughter, Miss D. Ancker, in the autumn of 1908, in offering me an opportunity to peruse the large collection of letters, rough-copies, drawings, and sketch-books left by Hjorth, which threw new light on his interesting life and work. Where it was previously necessary to resort to guesswork alone, we are now able to base our statements on established facts and to follow Hjorth’s train of ideas almost from his first, to his last invention, and to see where he has right and where he failed.

In the following pages, an account will be given of the results of these recent researches in connection with what was previously known about Hjorth.

Charlottenlund 1911.

_Sigurd Smith._

CONTENTS.

Page

Preface.

Søren Hjorth:

Childhood and Youth 1

The Railway 4

Electricity 7

Hard Times 18

Sources 29

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SØREN HJORTH.

Childhood and Youth.

Søren Hjorth was born on the 13th of October, 1801. He spent his childhood at Vesterbygaard, an estate rented by his father, Jens Hjorth, in Jordløse Parish, north of Tissø. His mother’s maiden name was Margrethe Lassen. Of their numerous children only two, besides Søren, survived childhood.

The parents became early aware that their son possessed great mechanical genius. He received his first education from the parish school-master. After Hjorth was confirmed, his father leased the beautiful estate Dragsholm, in Odsherred County, where he remained for many years, and after the death of his first wife, he married baroness Zytphen-Adeler.

Though he did not have an opportunity of learning much in his childhood, Hjorth succeeded in his youth in passing an examination which admitted him to the Bar. Later on he became the steward of Bonderup Estate, near Korsør, but in this position he did not feel satisfied, and in 1828 he became a volunteer in the State Treasury, in Copenhagen. In 1836, he advanced to the position of Clerk of the Exchequer and secretary. Although Hjorth’s occupation, during the last 30 years of his life, was mainly that of a civil engineer, he always continued to be addressed as Secretary Hjorth, and by this title he is still remembered by some of his surviving contemporaries.

Hjorth’s interests while at the Treasury were not concentrated solely on his work there. Mechanical problems always fascinated him. It is told that, during this period, he made all kinds of experiments at Dragsholm, and, among other things, he constructed a thrashing-machine. In 1832 he constructed a rotary steam-engine, which was made by Schiødt, a mechanic residing at St. Annae Plads, and, upon Hjorth’s application, it was bought by the King for 500 rixdollars in notes. The King donated it to the newly founded Polytechnic Institute, this being the place where it might best be utilized and »where this original domestic invention might most suitably be placed«. The same year, Hjorth described in »Ursin’s Magazines for Artists and Artisans« a steam-car, invented by him and adapted to be propelled by means of the rotary steam-engine. So Hjorth once more made a petition to the Government for a subvention of 2000 to 2500 rixdollars to assist in the practical manufacture of this car. The decision on this application was postponed, however, at the suggestion of Professors Ørsted, Zeiss and Forchhammer, because Hjorth had not yet finished the installation of the boiler for the first steam-engine at the Polytechnic Institute. Hjorth did not succeed in making the engine work, as it was not made with sufficient accuracy. The sum for which the car was to be made, was never granted, as petitioned for, although Hjorth had given up using his rotary engine for it; and the car itself was probably never built.

At that time, the use of steam-cars on the country roads attracted great attention in England, and many different constructions appeared. In 1834 Hjorth, aided by subventions from the »Rejersen Foundation« and the Government, went to England, in order to acquaint himself with the use of these steam-cars on high-roads and railroads. During these years he very actively investigated the use of steam-power, especially as a means of propulsion for vehicles and ships. With admirable interest and diligence he studied the steam propelled road-carriage, and for a long time he considered that to be the future means of conveyance. Although he did not succeed in getting his own steam-carriage put to practical use, he made many experiments on a steam car, and I am told by one of his passengers that on the level streets of Copenhagen and Frederiksberg all went very well, but the carriage could not climb Valby hill.

During these years, Hjorth also attended the lectures at the Polytechnic Institute, and he was especially interested in Ørsted’s lectures on the physics of the globe, and on electricity and magnetism.

Notwithstanding his unsuccessful experiments with the rotary steam-engine, Professors Ørsted, Zeiss and Forchhammer had to give him a warm recommendation, when he made a petition to the Ministry in order to get his expenses refunded by the Government. They mentioned his indefatigable zeal, his great diligence, and the considerable expense borne by him in the pursuit of his researches. The numerous and expensive experiments absorbed all the money Hjorth could procure: not only his salary was spent, but also such funds as he was able to raise among his friends.

The Railway.

In 1839 Hjorth made a journey to England, France and Belgium. By that time, he seems to have come to the conclusion that steam-carriages running on rails, are preferable to steam-carriages running on the high-road, at any rate he mainly studied locomotives and railroading during this journey.

After his return to Denmark, he spent some years as manager of Marschall’s piano factory, though still at work with his railroad schemes, and in 1840 he happened to find a man named Schram, a book-keeper, who shared his interests and was able to assist him in the realisation of his ideas. In 1840, these two men published a detailed calculation of the probable revenues and expenses of a railroad between Copenhagen and Roskilde. This project, however, did not arouse any interest, and people were mostly inclined to smile at the idea, and it appeared impossible to induce competent men to take, any interest in the scheme, much less to invest money therein.

Then, in 1841, they applied to the young »Industrial Association« which body referred the case to its special committee of commerce. Even this committee did not seem much inclined to listen to Hjorth’s and Schram’s proposition, but their undefatigable energy finally succeeded in persuading the committee of commerce to convoke a large meeting to be held on the 24th of March. Here it was decided to make an application to the Government for the surveying of the proposed railroad line and, to the surprise of many, the petition was granted. Hjorth, possessing distinctive agitatory faculties, showed great activity, delivering lectures and exhibiting models, and tried thereby to excite interest in his schemes. His contemporaries describe him as a sociable man of a winning and lovable disposition and possessing a certain persuasive power. He was well liked by his friends as well as by his many casual acquaintances. In 1841 both Hjorth and Schram were elected members of the Board of Representatives of the Industrial Association, and from 1841 to 1843 Hjorth was the vice-president of the association. Now there began to be some sympathy for their cause, and the Board of Representatives of the Industrial Association showed a willingness to follow the sub-committee elected, consisting of the two motionists and Lector, (later Professor) Wilkens of the Polytechnic Institute. The strenuous efforts of this sub-committee resulted in the Industrial Association submitting, in January 1843, an application for a franchise to form a stock-company for the purpose of building a railroad from Copenhagen, by way of Roskilde, to a sea-port on the western coast of Sealand. This franchise, was granted, for a period of 100 years, and on the 16th of April 1844 the Industrial Association issued a public invitation to take stock in a company whose stock capital was to be 1-1/2 million rixdollars, a very considerable sum for those times. As early as in the beginning of May, most of the stock was taken--mainly in Hamburg. While the confidence in a scheme of this kind was but slight in Denmark, the speculation in railroad stocks was nearly culminating at the stock-exchanges of Germany and England; as a matter of fact, it became near being a swindle. The Sealand Railroad Company was founded on the 2nd of July 1844, and Hjorth became its first technical director, while Schram became its first general manager. The Industrial Association received 15000 rixdollars for the franchise, and from this sum it paid 3000 to Hjorth and Schram.

In 1843, Hjorth was unanimously elected president of the Industrial Association. In 1845, he had to resign this office, but as it appeared very difficult to concentrate the votes in favour of a new president and vice-president, »Secretary Hjorth, to meet the general demand, accepted the vice-presidency«, which office he then held for a year.

In the meantime, the railroad company had finished the construction of its first piece of road, from Copenhagen to Roskilde, and this was opened for traffic on the 27th of June 1847, some days before the time limit fixed. Even at that time it was decided, owing to Hjorth’s influence, to extend the road to Korsør. The cause of the delay in commencing this work was the railroad crisis which had just broken out in Germany and England, making it impossible to obtain money for the construction of railroads. This road, therefore, was not constructed until the government, in 1852, guaranteed an interest of 4% on the capital invested.

Hjorth retained his position for about 4 years, and concerning this period he writes: »All the great difficulties and obstacles to be surmounted during the construction of the road influenced my health to such a degree that I broke down and was forced to abandon my position as technical director of the railroad before the expiration of my term of office, in order that I might take a water-cure at Klampenborg«. After he had, to some extent, regained his health there, and another board of directors had been elected, he made a travel to England which turned out to be of such great importance that we will describe it more fully in the following.

Electricity.

After Faraday, in 1831, had discovered how an electric current might be produced by means of a magnet, many people busied themselves by trying to put this invention into practical use, and numerous attempts were made to construct electro-magnetic and magneto-electric machines for useful purposes.

No wonder that these efforts attracted Hjorth’s attention, and, as early as 1842, he had drafted an electro-magnetic machine, consisting of a stationary circle of magnets, whose poles were directed against the poles of a moveable circle of magnets. In 1843 this sketch was deposited with the Royal Scientific Society, but the sketch itself, as well as the explanation belonging to it, are very incomplete.

In the month of April, 1848, Hjorth made a petition to the government for a subvention of 200 rixdollars, in order that he might go to England to get an electro-magnetic machine[1] designed by him, made there. Hjorth had noticed that, in a piece of iron encircled by an electric current, the magnetism only to a certain extent would increase, with the strength of current, there being a point of saturation for the iron. When this point has been reached, it will be of no use to increase the intensity of the current, since the magnetism will not increase any further. On the basis of this observation, Hjorth had constructed his machine, but he had confided the details thereof only to Professors Ørsted and Forchhammer. In the report on Hjorth’s petition made by these two professors to the Board of Trade, they, curiously enough, take exception to the above-mentioned observation by Hjorth, while its correctness will now be acknowledged by any electrician. These professors, however, advised that Hjorth’s petition should be granted, using this liberal argument, worded by Ørsted: »Regarding the petitioner’s new electro-magnetic machine, we must state that we find it quite ingenious, and although we are not convinced that it will produce remarkable effects, we should consider it useful to have a working model executed. Having during so many years worked for this case, the petitioner might perhaps, by the execution of such a model, be enabled to make some further invention, which would bring him nearer to the goal. Indefatigable zeal has often accomplished its purpose, where science had to declare the means at first used, to be entirely inadequate, but where, by continued work, entirely different means, previously unknown to the inventor, were found. Inasmuch as the sum of 200 rixdollars asked for is so small, we find it advisable to grant the subvention. Still we cannot refrain from remarking that the petitioner’s machine may just as well be made here as at any other place«.

Thus the discoverer of electro-magnetism cleared the road which was to lead to the most beautiful application of electro-magnetism, that application which, before all others, has been of radically reforming importance during the last half century, thereby throwing double splendor on Ørsted’s name.

Soon after his arrival at London, in the summer of 1848, through a firm which he knew from an earlier period of his life, Hjorth made the acquaintance of a nephew of Bramah, the renowned mechanician and inventor of the Bramah-lock. Hjorth’s invention was then laid before a friend of Bramah’s, a civil engineer named Gregory, who had made the study of magnetism his specialty. Gregory at once persuaded Bramah to bear the expense of making a machine, and of securing patents in England and several other countries, on condition that the expected profits should be divided between him and Hjorth. Later on, B. Taylor and Normann Innis were taken in as partners, paying together £1000, and then Charles Stovin (£600) and Robert Broad, of the Henley Iron Works (£500). Two machines were now made, according to Hjorth’s directions, by the firm of Robinson & Sons, Pimlico, London. One of these is shown in Fig. 1, and is apparently quite an ingenious imitation of the steam-engines of those days. _C_ is a movable, _A_ a fixed electro-magnet. Their peculiar shape, involving several conical pins fitting into corresponding cavities, was thought to be advantageous for the distribution of the effect of the magnetic force over a longer stroke. The »piston« _C_, reciprocating up and down, drives a crank shaft having two opposite cranks. To either of the cranks there is a corresponding group of magnets. An eccentric fixed on the shaft, moves a »slide valve«, alternately closing the circuit of one or the other of the two groups of magnets. When the one piston is at its lowest position, the circuit of the other group of magnets is closed, and its piston is attracted, until it reaches its bottom position; then the current is shifted, and the other piston attracted, etc. In order to avoid the formation of sparks at the circuit breaker, an ingenious device was provided, closing the current of one group of magnets, immediately before that of the other one was broken. The first machine was made with a 4 inch stroke, the next one with 13-1/2 inch stroke. The magnetic attraction per square inch of the piston, had about the same magnitude as the pressure per square inch in the low pressure steam-engines of those days. The patent application was filed in London as early as in October 1848, and it was granted on the 26th of April 1849[2]. On the 21st of September, the same year, Hjorth obtained a fifteen year monopoly in the kingdom of Denmark, to manufacture machines, utilizing electro-magnetism as motive power in the above described manner.

The larger of the machines here referred to was shown in action to several technical experts, and created considerable sensation, especially on account of the great length of stroke attained--13-1/2 inches--and the uniform motion of the machine. The machine is mentioned in »Mining Journal«, for the 5th of May, and 16th of June 1849, and an extract of these articles is published in the »Flyveposten« for the 3rd of July the same year.

Hjorth was invited to show the machine at the Royal Society, and at the annual meeting of the Society of Civil Engineers, of which he was a member. It was exhibited at the Universal Exhibition in London, in 1851. In the catalogue it was highly commended, and it received the only prize-medal awarded to electrical machines.

There was, however, one essential obstacle to the practical use of this machine, namely the lack of means for cheaply producing electricity in the quantities required by the electromotor. Wet batteries were expensive to use, and if the machine were to become useful in practice, a powerful »dry battery« would be a necessity. Most of the then known machines producing electricity, were fitted with permanent steel magnets, and as the point of magnetic saturation of steel is low, these machines were unable to produce any considerable quantities of electric energy. Hjorth therefore imposed upon himself the task of building a dry battery. His sketch-book from 1851 is full of new schemes for such batteries and improvements on those already existing (Woolrich’s, Elkington’s and Paine’s). From this it appears, among other things, that he was fully aware that, when the spools suddenly entered or left the field, difficulties would arise in the commutation, and he therefore improved the machine by bending the field magnets, obtaining thereby a gradually increasing and decreasing field, the same thing which is, nowadays, attained by using pointed or obliquely cut pole-shoes.--It would be very tempting to study more closely these sketch-books with their neatly colored drawings, showing how many different ideas have been fostered by him, before the actual production of the first dynamo, in 1854. Most of the descriptions and notes have been written in the English language, which he used almost as readily as his native tongue. On the 1st of May, 1851, Hjorth writes in his sketch-book, beside a sketch of a machine having copper discs for armature conductors and cast iron electro-magnets: »_By passing the current on the said way round the Electromagnets, these will of course be excited in proportion to the strength of the same, and the more they are excited, the more will the discs be influenced by the magnets, a mutual action thus taking place_«.

So it appears that Hjorth, as early as on the 1st of May 1851, with perfect clearness, has pronounced the dynamo-electric principle.

Under the date of June 24th, 1851, we find sketched out another beautiful idea for the construction of a dynamo. It must be regretted that this machine has not been executed, as it would certainly have proved superior to his dynamo of 1855, which has many points in common with this project. Fig. 2 shows a reproduction of this page of the sketch-book. There is no descriptive text to this sketch, only at one side of the drawing, these very significant words are written: »Magneto-Electric arrangement with mutual action«. All the six powerful held magnets are of cast iron, and they are wound so as to be magnetized by the current, produced by the dynamo itself[3].

In November, 1851, Hjorth returned to Copenhagen, and here he continued what he had commenced in England. In May, 1852, he deposited with the »Society of Sciences« some papers, signed by Professors Scharling and Forchhammer in December, 1851. These papers contain two descriptions, written in English, and two drawings of »dry batteries«. These consist of 3 or 4 circular rows of vertical steel rod magnets, placed one above the other, and disposed round a vertical shaft, carrying 2 or 3 circular rows of armatures. Each armature consists of a piece of soft iron, and is wound with a strip of copper, in a special manner. There are, in each row, as many armatures as magnets. The hollow shaft, as well as the magnets, which are fitted with shoes of soft iron, are wound, and encircled by the current produced in the armatures. With regard to the magnetic arrangement, this machine comes very near to the one patented by Brett in 1848, and it will be noticed that it cannot be said to be constructed according to the dynamo principle, as the »mutual« action plays no important part, the magnets being permanent steel magnets, hardly adapted to receive much extra magnetism by the current of the machine. Hjorth points out, as the novel feature of these machines, the division of the steel magnets into many small ones, with an armature corresponding to each magnet. Hereby he claims, for the same weight of the steel magnets, a larger capacity of the machine than if he had used fewer, but larger steel magnets[4]. The machine is fitted with a commutator for direct current.--In March, 1854, the sketch-book contains another sketch of a dynamo, with clear indication of the dynamo principle, approximately as it was patented on the 14th of October the same year[5]. This sketch is reproduced in Fig. 3. The machine has two permanent cast iron magnets and two electro-magnets. The armature cores are fitted with oblique pole-shoes. The description is very brief and contains the same as the patent specification.