After heavy suffering Professor Ferdinand Braun passed away the morning of the 20th of April, 1918, in America. The field of Physics and associated technology lost a very innovative researcher, particularly in the field of electrical oscillations. Ferdinand Braun is also rightfully considered the creator of wireless telegraphy. In high honor and acknowledgment of this fact the 1909 Nobel prize in Physics was awarded jointly to him and G. Marconi. His work and ideas live on in the modern development of radio telegraphy.

At the request of the publisher we present a short outline of his work in this magazine.

F. Braun's interests were extraordinarily extensive and versatile, encompassing a broad range of scientific activity including all areas of physics. It is not possible in this essay to give an account of his exhaustive accomplishments, even if we limited it to only the most important. Therefore we will only discuss his work in electrical oscillations that we cooperated on, both as assistants and several years under direct supervision. It is certainly essential to touch on a number of his remaining projects. Already in his early investigations there exist seeds for important developments in wireless telegraphy. Different results from Braun have become lasting datum of general physics and some of the questions raised by his data have sustained work and remained interesting to this day. (TS)

One of these problems was the clearing-up of procedures in galvanic elements. F. Braun pointed the way to correctly compute electromotive force (EMF) from thermal data. Before him one believed that the EMF of the galvanic elements could only be computed from the heat of the chemical reaction. The acceptance of this theory was shown by Braun to be inadequate. He refuted this theory by theoretical considerations on one hand and by detailed measurements on the other, giving us information still of value today.

Braun's first relevant work originated in the year 1878. In the year 1882 Helmholtz dealt with the (same) problem and introduced the now well known term "free energy" TS

Braun was also the first to scrutinize the effect of pressure on galvanic reactions and EMF. This special problem was finalized (finished, laid to rest) by R. Gans at the Stausbourg Institute.

Für Braun gab die Beschäftigung mit diesen Dingen die Anregung zur Aufstellung des sogenannt LE CHATELIER-BRAUNschen Prinzips, eines bekannten Satzes, dessen Gültigkeitsbereich nicht in vollem Umfange aufrechterhalten werden konnte.
Beyond my ability to translate.

In the year 1891 Braun discovered a new phenomena in the field of electrolysis which he called "Elektrostenolysis". If a current is sent through a small gap in an electrolyte solution (e.g. silver nitrate solution) metal separation takes place at the gap. (the gap seems to have acted as a third electrode) This strange feature, whose complete explanation is probably still pending, was examined in detail by Braun. Following the work and investigations of Becquerel, Braun pursued "elektrocapillare" reactions. There is a reaction between two solutions separated by a porous wall, where they diffuse through the pores into segregated layers. TS!

Around the same time Braun busied himself with the effects which arise with dripping electrodes.
He proves that Pellat's conclusions regarding the difference in potential between a metal and the solution of one of it's salts are in error. TS He presents opinions regarding chemical decomposition caused by introducing mercury drops into liquids: one would speak now of decomposition by absorption. Furthermore he probably first formulated the relationship that exists between the change in volume of a saturated (with dissolved salts) solution and the dependence of solubility on pressure which he justified thermodynamicly. TS
Furthermore Braun declared the interesting fact that the compressibility of water, in which certain salts are dissolved is less than pure water.

In his work Braun relied heavily on written principals. But it is not only his results and questions that are interesting, but also the type of his experiments. He possessed extraordinary luck (fate) and a large amount of ingenuity in the development of equipment to facilitate his experiments. In this way measuring instruments and apparatus were developed, which produced great independent interest and found their way into physical investigation and measuring techniques.

Here also the Braun tube, those belongs to the physicist and electrical engineer in such a way trusted cathode ray tube. By its practically inertialess functioning it gives the possibility of examining the course of variable rivers and tensions up to extraordinarily high frequencies. This of Braun equal in its first publication stressed characteristic of its tube gives her a privileged position under all oszillographischen devices. For the fast oscillations, which are used in the radio engineering, the BRAUN tube is the only means, in order to examine the course in the detail; as such it carried many services out in the hands BRAUNS and its coworker. By use of a glow cathode (pain ELT) it was perfected further and is today an indispensable and aid much-used with works with alternating currents of all frequencies.

of Brauns, after their emergence the meaning won for the wireless telegraphy, are except the example evenly specified above all to call its investigations work over the stromleitung by certain bad-leading krystalle. in the year 1874 already describe Braun the following fact discovered by him: if one sends an electric current by kupferkies, sulfur gravel, bleiglanz, pale ore and such, then one that its strengthens is not proportional emk. if thereby the electrodes, is differently constituted, observes then hangs the amperage also of the direction of the difference of potential put on starting from Braun has for example with its first arrangements of differences of the amperage of 30 % for opposite directions found with later arrangements was still substantially larger the differences in the amperage, so that one can speak practically of the fact that the river goes through only in a direction this feature, which represents a deviation of the stromleitung from the Ohm's law and which is called unipolar line, has a very important application found: on it are based from Braun invented and krystall detectors introduced to the practice of the wireless telegraphy.

deviations from the Ohm's law play in order the electrical oscillations at all an excellent roll not only for the proof of the oscillations leaders used, with whom the river of the tension is not proportional, but also for their production transmit e.g. are such a leader, with whom no linear relationship between river and tension exists, in the same way the arc, the electron tube one can state that each new feature or new arrangement, which exhibits a sufficient expressed "deviation from the Ohm's law" results in at the same time a new method for production or to the receipt of oscillations. in this connection it is interesting to point out that Braun from its earliest work to several times procedures examined on its deviation from the linear law (except regarded the above still: unipolar line in, oscillations of loaded strings, flexible aftereffect features gas).

with the problems of the wireless telegraphy busy Braun from the year 1898 the following was present itself off at that time: in the year 1895 A. had used popoff the kohaerer with more klopfer and relays in connection with a aerial (receiving antenna) for the registration of thunderstorms. in the same time marconi send-tries with a righischen oscillator and on it hung a aerial (transmitting antenna) employed to the receipt used he had an arrangement, those was substantially identical with the popoffschen. in the year 1897 succeeded marconi bridging with its arrangement with spezia distances up to 15 km wirelessly. it was shown soon that for the achievement of larger ranges a disproportionately much stronger enlargement of the antenna height was necessary, so has e.g. slaby (1897) for the overcoming of a distance of 21 km over country aerial of 300 m length related, which were carried by ballons. In this way, without adding new thoughts and without realization of the playing physical procedures the new, shining invention could obviously develop MARCONIS hardly further.

Both carried F. out Braun: It recognized the side in principle of the procedures, which work during the relatives arrangement with clear view, and it created those arrangements, which form also today still the foundation of the wireless telegraphy being based on this realization. One will ignore probably its achievements best, if one itself carried back to this first time and the development of the wireless telegraphy of the historical point of view regards.

It is appropriate thereby to divide the complex of the physical features, which arise in the wireless telegraphy, in three groups which are connected naturally with one another, which can be treated however nevertheless separately:

1. The procedures in the transmitter.

2. The propagation of the electrical waves.

3. The procedures in the receiver.

How did it stand at that time with the questions of the first group? Even the main question was not solved: with which wavelengths or frequencies one it with the Marconi Transmitter to do has. No trained means were present, in order to measure these sizes so fundamental for the radio engineering. One was inclined to the opinion that one would have to do it with the Marconi Transmitter with very short waves, which are produced by the balls of the spark gap as Righi oscillator thus with wavelengths of the order of magnitude of a meter.

Braun it recognized now that this could not be correct. Rather the air leader grounded by the spark gap had to be regarded as a whole (spark balls + wire), and this system comes a basic self-wave, which is certain mainly by the length of the aeriales. It was therefore to be expected that one has to do it with the Marconi Transmitter not with the HERTZ waves strictly speaking, but with many longer waves. This us today as naturally seeming view of the whole procedure was little than generally recognized probably at that time nothing. The realization of the correct view was determining for the whole further development of the radiotelegraphy.

Now already at that time a means was well-known, in order to produce electrical oscillations from such large wavelength to: that sucked. Condenser circle. Oszillatorischen unloadings of such a circle had been examined already 1862 by FEDDERSEN and later LODGE also resonance attempts with them employed. Braun recognized immediately the large advantages, which the use of the condenser circle in the radio engineering offered. Its basic idea was the following: Against a transmitter for wireless telegraphy two different tasks are placed: first of all as strong, high frequency an alternating currents as possible must be produced, then must the same in radiation, i.e. into electrical waves, be converted in it. The Marconi Transmitter, which is more closed ", but" open "in contrast to the condenser circle no" an oscillation circle, radiates excellently. On the other hand the condenser circle, which does not radiate practically, for the production of strong, high frequency rivers is far superior to the open oscillation circle. From combination of both things now the famous BRAUN coupled transmitter resulted. In its first execution form it essentially existed circles directly or inductively coupled aerial, which contained no spark gap now of a condenser circle with spark gap, which by an inductor one operated, and of with that. The oscillations developing in the condenser circle produce rivers in the aerial and by this are radiated.

A similar zwiefache task as when sending develops also with the receipt. First the electrical waves arriving from the transmitter must be caught, whereby they are converted into high frequency rivers, which cause then for their part the indication rendition in the telephone or write apparatus. The aerial is suitable also here, like it POPOFF and MARCONI related had, excellently for the receiving of the waves. It is suitable however many less well for appropriate utilization of the caught energy, to which, as Braun recognized, again the condenser circle is outstanding suitable. Thus from connection of the aerials with the coupled BRAUN receiver resulted to one or more condenser circles.

Further following to the BRAUN idea course, the here following is mentioned: With the simple Marconi Transmitter one could increase the energy with given aerial only by the fact that one turned into to ever higher charging voltage. That involved an enlargement of the funkenlaenge, which caused a so increased energy waste in the spark again with the small capacities of the aerial that the total profit at useful energy became illusory. In contrast to it one has the possibility with the BRAUN transmitter of increasing by suitable choice of the capacity of the closed circle the usable energy in much stronger measure. The spark gap in the aerial is missing during the BRAUN arrangement completely, it is in closed circles, where it works many less harmful. When Braun inserted the condenser circle into the transmitter, these energetic considerations could appear as very substantial. At that time only few measurements were present over the energy consumption in the spark. Later investigations, in particular the work of J. ZENNECK, M. VIENNA and other one, how Braun stresses in his Nobel speech expressly, showed that into the closed circle always the crucial role to the transfer of the spark from the antenna is not to be attributed, which one had to accept after the initial conditions of the knowledge.

In addition, apart from this energy question the BRAUN transmitter means a completely substantial progress opposite the original Marconi Transmitter. It is only referred to the following advantages:

1. One wins a larger liberty in the choice of the height of the primary tension.

2. The demands, which must be made against the isolation of the antenna, are much smaller with the BRAUN coupled transmitter than with the simple transmitter, which must be isolated statically. This fact has great practical importance.

Vibratory systems with several degrees of freedom, from which the BRAUN feed back control systems represent a special case, had been examined theoretically and also experimentally several times, in particular in application to mechanical and acoustic problems (lord RAYLEIGH, M. VIENNA among other things). The creations BRAUNS animated the theoretical interest and gave the means, in order to carry out and examine the features of feed back control systems comfortably. Thus further physical circles only familiarly with the laws of these important procedures, with which one encountered results, which had to appear unexpected for the theoretically not training at that time. For example on the occurrence of two from each other different frequencies with the coupling of two completely same systems.

Here the still following is to be noticed concerning the consequence of the BRAUN invention, which appears quite substantial to us. It can mostly almost be considered as a characteristic of a really fundamental invention that its meaning exceeds the far over direct application purpose, to which it was originally created. This applies at the BRAUN condenser circle extremely. The whole technology of sending experienced many transformations since the time, where Braun introduced the closed circle to the practice. The transmitter with the slamming spark was replaced by the WIEN transmitter, with which the fundamental invention of the delete spark became related. But with the WIEN transmitter the straight closed circle is an indispensable component. Then the era of the undamped waves, first the Poulsensender, came then through ALEXANDERSON, GOLDSCHMIDT, COUNT ARCO high frequency machine and finally the electron tube transmitter which is based trained among other things on the MEISSNER feedback principle. With none of these methods the closed condenser circle may be missing, if the utilization should be favorable. Its function is different depending upon the circumstances, but its meaning always remains prevailing. Similar applies also concerning the receipt methods, which likewise experience the most manifold changes in the course of the development. The use of the electron tube brought a complete circulation and created possibilities, of which in the first development years hardly could be thought. In addition, with the most modern receipt mechanisms the use of the closed condenser circle remains one of the best and usually used means for the achievement of high a selectivity as possible.

If we link coupled oscillation circles thus in the wireless telegraphy with BRAUNS name, then happens with full right. Because, although the condenser circle actually as electrical vibratory system already for a long time before the radio telegraphy admits was, is it nevertheless certainly BRAUNS earnings/services, its meaning for this technology to have clearly recognized and it to the same introduce.

We turn now after this digression back to the work, which followed at that time the emergence of the BRAUN transmitter. After BRAUNS ideas had worked satisfactorily equal with its first attempts, which were implemented mainly by M. CAN GATE and J. ZENNECK, developed a large number of secondary questions, whose solution became necessary. Above all it applied to prepare measuring methods and arrangements, which were adapted to the recent branch of the technology. The measuring methods for amperage, tension and such could not be taken over for the fast oscillations directly from electro-technology at that time. Far also completely new requirements came closer to the measuring technique: the measurement of frequencies or wavelengths and of logarithmic DEK rem ducks. In principle the use of the resonance features for these purposes was well-known since BJERKNES. These methods had however for the new area (wavelengths by other order of magnitude, to be a hundred times more largely completely substantially reworked. Above all an easily handling and comfortable apparatus had to be created for the measurement of frequencies (frequency meters or wellenmesser). The methods were prepared in Strasbourg of J.ZENNECK and them for the measuring technique of the wireless telegraphy became fundamental among other things: They led to the first really practically useful KoePSEL KoePSEL-DoeNITZ wellenmesser, which consists of a condenser circle with calibrated variable condenser and thermal current indicator. The wellenmesser remained unchanged today in principle until.

One of the most substantial components of the receipt mechanism is as well known the detector, i.e. a device, which make themselves the high frequency rivers training in the receiver under the influence of the arriving waves displayable. As detector became in the beginnings of the wireless telegraphy sucked. Kohaerer uses. This remained however despite the efforts of a whole set of inventors an extraordinarily difficult and inkonstanter apparatus, which was suitable for technical purposes only quite unsatisfactorily. It is thus understandably that the efforts of many researchers aimed at it, new, to find better suitable detectors. Braun the large merit/service is entitled also here a detector class to have created those that concerns simplicity, also today still unbesiegt stands there. Through long time it had displaced all other detectors and had controlled alone the receipt. There is this the Krystalldetektoren, whose impact we above stated, and which began to already use Braun in the year 1899 for the receipt.

Beside these fundamental work, which referred directly to the procedures with sending or receipt, BRAUNS interest was stressed by questions, which stand in connection with the propagation of the electrical waves.

The task of arranged sending was understood by Braun by completely different side. The principle of its method is the following: two or several separate vertical air leaders are used, which are set up in distances comparable with the wavelength and which are fed with out of phase oscillations. One can select the distances or the phase shifts in such a manner that the radiation preferably takes place after a certain direction. Such attempts were accomplished in the years 1904 and 1905 on the Strassburger drilling place polygon. The field was measured at distances, which amounted to some wavelengths, with a bolometer arrangement. The result corresponded to expectations. This theoretically perfect method for arranged sending does not have up to now for long waves an entrance into the technology found, mainly probably, because it complicated nevertheless rather and expensive plants required. It is however impossible that the technology falls back with the further development of the radio telegraphy, in particular the short-wave transmitter, again on the BRAUN thoughts similar arrangements is by the way already carried out.

In the last Vorkriegsjahr busy itself Braun again with the arranged receipt. This time in connection with other general questions. Closed oscillation circles should be used, contrary to up to then the generally used open circles for catching the electrical waves. With these attempts 1913 in Strasbourg the coil aerial, which found furthest spreading today as receiving antenna, developed. The framework receipt offers substantial advantages in relation to the receipt by open oscillation circles. One can free oneself with him from disturbances, which come from certain directions, and has thus larger stoerungsfreiheit. Further one has the possibility of the wireless bearing etc.. These advantages, which are today probably generally recognized, were clearly recognized by Braun. In its first report attempts already are for the determination of the direction of the waves sent by the Eiffel Tower. To it then investigations attached over the direction regulation of the electrical vector in the field of the arriving waves. For the first time the field strength in waves of the wireless telegraphy (likewise Eiffturmwellen in Strassbourg) was continued to intend according to the absolute value. Today the knowledge of the field strength of the waves arriving at the receiving place is indispensably become the evaluation of functioning the stations. All modern methods to their measurement the BRAUN arrangement is essentially the basis.

We have try a short outline of BRAUNS work on that areas of the wireless telegraphy to give and we have us anxious show, how fundamental its ideas remained also for the modern development of the radio engineering. If one summarizes above the saying, then one will be able not to attribute to the BRAUN achievement an innovative role in the development of the wireless telegraphy. Braun clearing up and creative on the entire area of the radio telegraphy and its name worked under of all first will always remain in the history of the development this beautiful area of application of physics.

The work, which Braun on that implemented areas of the electrical oscillations, gave it suggestion to a whole number of other work, which in a certain connection with it. Thus it placed the task to the feature of the anisotropic refraction of the optics the analogue with HERTZ waves to manufacture itself (brick lattices). Thus he found furthermore to a feature, which was with HERTZ waves well-known and often examined, the optical analogue. It concerns the HERTZ lattice attempt, which is accomplished as well known as follows in its classical form: one lets a linear polarized electrical wave be noticeable on a screen, whose wire distances are small against the wavelength. If the electrical vector stands perpendicularly to the gitterdraehten, the wave is nearly unweakened let through. Against it if the electrical vector swings parallel to the wires, then the wave is strongly reflected and let through only weakly. A lattice with the refinement necessary for visible light radiation is mechanically not producible. Now the most interesting observation made Braun that the metal fittings, which one can receive on glass by atomization from thin wires by means of strong condenser TLA dung, a behavior shows, which is completely similar to the behavior of the HERTZ lattice. If one lets go through linear polarized light, its polarization plane is parallel to the axle of the sputtered wire, then the preparation, which one observes in the microscope with weak enlargement, appears dark. If one the polarizer 90, then the field lightens itself. Braun this by him interpreted discovered feature, by assuming that the metal deposit exhibits a fine sub microscopic lattice structure, and it has this explanation by further, finely invented experiments supported. These last attempts (in particular the thesis of UNGERER) appear proving for the fact that one has to do it here with the Hertz lattice attempt in the visible spectrum. Braun in a set of work tried to use the feature for the analysis of finest structures and organic things.

We want our outline to be content with these examples, by which BRAUNS investigations and drafts are not by any means exhausted to new work on that border areas between optics and electricity, and want thereby over BRAUNS research work to close.

As a teacher Braun everything, which was vergoennt it to work in its Institut will remain unforgettable. It left it to everyone to act and to its inclination follow after its own individuality. It pursued all work with continual interest and supported with advice and act and its advice always was more up than clearing: Braun foreseeing of the features and a feeling of experimenting were own, which cannot be learned and which only chose researcher nature are given. These characteristics, to which it owes its researcher success to a large extent, benefitted also its pupils.

As a personality Braun worked by its naturalness and friendliness and by its extraordinary sympathetic consideration uncommonly attractively.

BRAUNS researcher achievements secure in the science a high honor place for it, and all, which had the luck to step with it into closer relations will always retain the memory of the large, world-experienced, intelligent and nevertheless so good-natured man with love and reverence.