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E. & F. N. SPON, 125, STEAND, LONDON. 



TK i 


As of late the employment of alternating current 
transformers has largely increased and become of 
great importance, indeed as they are called upon to 
play a striking part in electric lighting from central 
stations, the author has thought a short notice of 
the development of this invention would possess 
some interest. This task appeared to be so much 
the more pressing, as many distorted versions of the 
invention and its priority have found place in the 
technical journals. 

The author has not let the reading of the large 
number of patents discourage him, and hopes that 
the following plain and concise statement of these 
researches will contribute towards the forming of a 
correct judgment as to the services rendered by the 
several inventors. 




As we wish to write cf those discoveries which led 
up to the invention of the transformer, we must go 
back to a time, old as compared with the modern 
development of electrotechnics. For the starting- 
point of our observations we shall take Faraday, 
who, like Newton in mechanics, led the way in the 
domain of electricity, and whose name stands in the 
most intimate relations with all inventions for the 
mechanical production of the electric current, and 
therefore with the later development of electro- 

The most important discovery for which we have Faraday, 1831. 
to thank Faraday is that of induction. This dis- 
covery was made by him in the year 1831, and 
intimated to the philosophical world in a paper read 
on the 24th November, 1831, appearing in the 
Transactions of the Philosophical Society in the 
year 1832. 

Faraday's first induction apparatus consisted of 
two coils of wire, the one being slid over the other. 
As he was passing the current from a battery through 
one of these, he made the discovery that each time 
the circuit of the coil was opened or closed an 



force was created in the second coil, 
which caused a fehart gush of current or induction 
current to flow, provided the circuit of this coil was 
closed, as might be through a galvanometer. The 
peculiarity of this induced current was, that it only 
flowed in the second coil during the time the current 
in the first coil took to reach its normal strength 
after closing the circuit, or on breaking the circuit 
during the time the current took to decrease from 
its normal strength to zero. 

This discovery undoubtedly belongs to the domain 
of the transformer, induction being the physical 
precedent upon which the transformer is based; 
indeed, a tranformer is in principle an induction 

Fm. 1. 

Fig. 1 represents the arrangement of this funda- 
mental experiment. The primary coil is connected 
with the battery, the secondary with the galvano- 


meter. The primary coil, in order to obtain the 
best effect, is placed inside the secondary, and on 
opening and closing its circuit the needle of the 
galvanometer is thrown to the one or the other side 

The arrangement, as in Fig. 2, made by Faraday 
showed itself to be an especially effective combina- 

FIG. 2. 

tion for the production of these induction phenomena. 
There were wound round an iron ring two separate 
wires of about the same length. The one coil was 
brought into connection with a battery, and to the 

B 2 


ends of the other a pair of electrodes were attached. 
The current from the battery being sent through the 
primary coil, lines of force were produced which ran 
almost altogether in the iron core. As the core 
possessed only a very small magnetic resistance, the 
intensity of magnetisation was very great, and on 
closing the primary circuit a strong inductive effect on 
the secondary coil was produced. Faraday obtained 
with this apparatus the first sparks of induction. The 
apparatus is all the more interesting as, although 
not completely without poles, it at least forms a 
closed magnetic circuit. It has much likeness to 
the non-polar transformer of Zipernowsky, Deri, and 
Blathy, but it may be easily shown to be not entirely 
poleless. Poles mean, in electrical as well as mag- 
netic circuits, those points between which the greatest 
difference of potential exists. A current without 
difference of potential can only flow in an electrical 
or magnetic circuit when the loss of potential in 
each part of the length of the circuit, viz., the 
product of resistance and current, is equal to the 
gain of potential, that is the magneto- or electro- 
motive force ; therefore a current without difference 
of potential requires that the resistance and magneto- 
or electromotive force in each part of the length be 
the same. Now the magnetic resistance of a sym- 
metrical iron ring is constant in all parts of the 
length of its magnetic circuit. In the case in 
question only one half of the ring was excited, 
therefore poles must have been formed at both ends 
of the exciting coil. The ratio of transformation of 


this apparatus of Faraday's was equal to unity, so it 
had therefore no claim to the designation of " trans- 

The induction apparatus of Faraday in its sim- 
plicity was in a certain measure the embryo out of 
which all dynamos and transformers have developed. 
We have seen how the first induction current was 
discovered by making and breaking the current from 
a battery in the primary coil. This method was at 
first adhered to, until Faraday remarked that when 
the secondary was quickly drawn out of or put into 
the primary coil, induced currents were also pro- 
duced without requiring to break the circuit, the 
wires of the secondary coil cutting the lines of force 
in the magnetic field of the 
primary coil. He then re- 
placed the primary coil and 
battery by a permanent 
magnet, which was likewise 
dipped into the induction 
coil, Fig. 3. 

From this, and from the 
later development of this 
invention, it follows that the 
question was not of a trans- 
former in the present sense 
of the word, but of a second- 
ary generator. Transformers 

as at present understood were first known in Europe 
as the Kuhmkorff's induction coil. Before we take 
up this invention we shall mention a much earlier 


and like invention, which had already been made in 
the United States in the year 1838. This was the 
induction coil of Professor Page, and was the outcome 
of another invention by Professor Henry, whose 
apparatus was only a single induction coil. The 

Henry and first public notice of Professor Page's apparatus 
appeared in the Silliman-Journal of 12th May, 1836, 
under the title, " Methods and trials of obtaining 
physiological phenomena and sparks from a heat 
engine by means of Professor Henry's apparatus." 
In May, 1837, Sturgeon published, in the "Annals 
of Electricity," in London, a description of the 
apparatus of Henry and Page. 

Cailan, 1837. Callan, an English student of physics in Minnoth, 
showed first, in the year 1837, that if high tension 
was wanted, it was necessary to employ thick wire 
for the primary and thin for the secondary coil. 
Before this time wires indeed of different lengths, 
but of equal cross sections, had always been em- 
ployed. His apparatus was not so bad as those 
before known, but still stood far behind that of 
Professor Page. 

Page, 1838. The arrangement of Professor Page's apparatus, 
which is shown in Fig. 4, was as follows : Two 
coils of wire well insulated from one another 
were wound on to a bundle of iron wires. A self- 
acting contact-breaker was put into the primary 
circuit, and consisted of a double lever E, having on 
one of its arms two parts bent downwards, so as to 
dip into two mercury cups. The movement of the 
part H, as compared with that of E, was so small 


that it remained always in the mercury. At M, 
however, when the lever was set in motion contact 
was broken and made. To prevent oxidation Page 
poured in a layer of alcohol over the quicksilver. 

FIG. 4. 

The continuation of the lever in the other direc- 
tion of the axis, which was borne by two pillars K, 
was bent backwards, and on its end carried a cylin- 
drical piece of iron standing before the end of the 
bundle of iron wires. If the primary coil were 
now placed in connection with a source of current, 
the iron core became magnetised, attracted the cylin- 
drical piece of iron to itself, and by raising the lever 
E broke the contact at M. The iron core then lost 
its magnetism, released the iron armature, and the 


play began anew. A counter-weight F, which could 
be shifted along another lever 0, allowed the play of 
the contact-breaker to be regulated. It will be 
found that this interrupter was very like that con- 
structed many years afterwards by Leon Foucault 
The effects which Page produced by means of this 
instrument were much more intense than those pro- 
duced by Kuhmkorff with his, as Page succeeded 
with only a single Grove element in inducing in the 
secondary circuit such a high electromotive force as 
produced sparks 4 inches in length through a 
vacuum tube a result that Ruhmkorff, although 
his invention created such a great and well-deserved 
attention, did not attain. In the year 1850 Page 
built a much larger apparatus. 

In order to give some idea of the magnitude of the 
electro-magnetic forces which came into play here, 
suffice it to say, that the exciting coils could hold 
suspended in the air in their interior an iron core 
weighing 520 kg. The primary or magnetising coil 
was of square copper wire, with a side measuring 
inch, and a battery of 50 to 100 Grove elements 
was employed, the immersed area of the surface of 
the plates being 100 square inches. This apparatus 
gave sparks of great length. When, with maximum 
currrent strength, the primary circuit was broken, 
sparks of 8 inch length were received. 

Ruhmkorff, Ruhmkorff constructed, in the year 1848, the so- 

called spark-inducer named after him, the object of 
which was also to convert currents of low tension into 
hose of very high tension. With this coil and like 


coils of larger dimensions effects were produced, but 
only such as were afforded by the common forms of 
frictional electrical machines. All things considered, 
it is not a little surprising that while the invention of 
the Ehumkorff coil was still in its infancy, the won- 
derful output of Page's apparatus was still, even in 
the year 1851, quite unknown in Europe. 

Fig. 5 represents the earlier form of the Euhmkorff 
apparatus. It consisted of a bobbin of good insulat- 
ing material ; thoroughly dried wood, or better, hard 

FIG. 5. 

rubber. The two end pieces of the bobbin were usually 
made of grooved glass discs, and were bound down to 
the bedplate of the apparatus by two wires. Inside 
the coil was the already often-mentioned bundle of 
iron wires. The primary or inducing wire was next 
wound upon the bobbin. As this wire had to carry 
currents of comparatively great strength, it con- 
sisted of only one or a few layers of thick wire. 
The circuit of this coil was completed as far as two 
terminals on the bedplate, first passing through an 
interrupter like what has already been described. 
Over the primary coil, and after a sufficient layer 


of insulation had been added, the secondary wire 
was wound. As this wire was destined for very small 
currents, it was of as fine wire as it was possible to 
wind. In order to obtain high potential it was 
necessary that the secondary should possess many 
turns. In the earlier coils a length of between 
8 and 10 kilometres was used ; in the coils now 
made this length has been increased to between 50 
and 70 kilometres. The ends of the secondary coil 
were connected to terminals insulated on glass 
pillars. It was not nearly sufficient insulation for 
the secondary wire to be covered with silk, but 
every layer was well soaked with dissolved shellac, 
and then well dried as it should be. A condenser 
in connection with the primary coil was placed under 
or in the bedplate, which was usually a box. This 
condenser was, and is still, often made thus : On both 
sides of a strip of paraffined paper, several metres 
long and of convenient breadth, tinfoil is stuck, at 
the same time leaving a sufficient margin of paper for 
insulation. The whole is then folded together suitably. 
The effect of the coil is substantially enhanced when 
the sheets of tinfoil are each connected to the circuit 
of the primary coil in such a way that the condenser 
is in shunt to the interrupter. 

In Fig. 6 is shown a newer form of Kuhmkorff's coil, 
with an interrupter like the mercury contact-breaker 
which we have before described. According as the 
movable weight is raised or lowered, the oscillations 
of the lever, and consequently the induced currents, 
follow one another more slowly or more rapidly. 



We find a further development or modification of c. T. & E. B. 
the invention of Page and Kuhmkorff, patented by the Bri s ht > 1855t 
brothers C. T. and E. B. Bright on 21st October, 
1852, and No. 2103 in the year 1855. In the latter 
of these patents the inventors state what follows con- 
cerning the nature of their inventions. 

FIG. 6. 

"A section of an induction coil made after this 
manner is shown in fig. 7, having a very strong 
effect. The primary wire, of which only a part is 
shown, is wound on an iron core, and outside is sur- 
rounded by an iron cylinder. Both of these are 
metallically connected by the flanges of the bobbin, 
which also are of iron. The secondary coil may also 
be surrounded by an iron tube, and if the resistance 
of the circuit be extraordinarily great with still more 



primary coils, or it may be also contained in the 
same tube as the primary. In cases where it is 
found necessary to increase the quantity of the 

FIG. 7. 

electro-magnetic effects, we find that the forms 
shown in Figs. 8 and 9 are very effectual, and may 
by varied on the same principle. 

FIG. 8. 

The iron core in the middle is wound with 
the primary wire, and is surrounded by the other 
iron cores, which are fixed into the large flanges of 
the middle core, and carry the secondary coils. 
Should still greater effects be required, more primary 



or secondary coils connected in series with the others 
may be added outside, in order to produce a greater 
extension of the poles and a more extensive induc- 

FIG. 9. 



This patent is interesting also for the fact that in 
it we find a disposition of parts, viz. the arrangement 
of several induction coils in ranks, and connected 
with one another in parallel, which nearly 30 years 
later was taken up and practically used by Gaulard. 

Among the patents of the year 1857 there is an Harrison, 
English one by Harrison, claiming as its object the 1857> 
passing of a primary current through one or more 
induction coils, and the connection of the secondary 
coils with the carbons of an arc lamp. There is 
nothing remarkable in the description. 

The last attempt to use induction coils for indus- Jablochkoff, 
trial purposes is met with in the year 1878. In this 1878a 
year Jablochkoff took out a German patent, which 



was also carried out in practice. He required 
currents of very high tension to feed his kaolin lamp ; 

at that time such currents 
could only be produced by 
induction coils. He writes 
as follows in his patent : 

"Die Herstellung einer 
elektrischen Beleuchtung 
nach meinen System be- 
greift eine Serie von Induk- 
tionsrollen in sich, wovon 
die inneren Drahte in eine 
elektrische Leitung einges- 
chaltet sind." 

Jablochkoff used inter- 
mittent direct currents as 
well as alternating cur- 
rents. The arrangement 
shown in Fig. 10 was for 
the former. He states con- 
cerning this : 

" In diesem Falle sind die 
Induktionsrollen mit Unter- 
brecher und Kondensator 
ausgestattet, oder man kann 
auch, wie die Zeichnung 
nachweist, einen und den- 
selben Unterbrecher fur alle 
Kollen anwenden. Die Induktionsrollen B 1 B 2 B 3 , 
nach einen beliebigen Prinzipe konstruirt, sind in 
der Nahe der Lichtherde angebracht." 



Concerning the employment of alternating cur- 
rents, Jablochkoff says : 

"Diese Disposition weicht von der ersteren nur 
durch die Weglassung des Unterbrechers und des 
Kondensators der Kolle ab. 

FIG. 12. 

"Die in Fig. 11 angewendeten Rollen sind in 
Fig. 12 detail! iert gezeichnet. Auf einer kreis- 
formigen Scheibe C aus weichem Eiseri erhebt sich 
in der Mitte derselben ein hohler Cylinder b aus 
Holz oder anderem isolirten Materiale; um den 
unteren Teil des letzteren ist die Hauptspirale a 
gewickelt, welche aus bandformigen Kupferstreifen 


oder anderem Metal le besteht. a' 1st die in gleicher 
Weise zusammengesetzte Induktionsspirale, deren 
Drahtenden zu den Lichtherden ftihren. Zwischen 
den einzelnen Windungen der Spirale sind Streifen 
aus Papierkarton oder einem anderen isolirenden 
Material angebracht. Die Spirale a ist in die 
Hauptleitung, wie Fig. 11 zeigt, eingeschaltet. " 

The second claim of tbis patent is also interesting, 
and reads as follows : 

"Die Einflibrung einer Serie von Induktions- 
rollen in den Umkreis eines beliebigen Elektricitats- 
generators zur Erzeugung einer Serie von Induk- 
tionsstromen. welcbe es gestatten, Lichtberde von 
verschiedener Intensitat durch eine einzige Elek- 
tricitatsquelle zu versorgen, was zur vollstandigen 
Teilbarkeit des elektriscben Lichtes fiibrt." 

JablocbkofFs system as just described was to be 
seen working in tbe Paris Exhibition of the year 
1878. A proper industrial application of tbis system 
does not appear to have taken place. 

Bri T h?i87*' In the ye{ir 1878 the brothers Bright bad also 
made further progress in tbe use of induction coils 
for electric lighting purposes, and in the same year 
they took out tbe English patent No. 4212, in 
which they described the use of alternating currents 
for working secondary apparatus or induction coils 
placed at various points where light was required. 
We shall here quote some very interesting sentences 
from this patent, which again show that tbe 
brothers Bright knew already in the year 1878 the 
properties of transformers suiting them for electric 


lighting purposes ; indeed they then anticipated the 
principles contained in the later patent of Gaulard. 
Here is an abstract from the description : 

" At each point where electric light is used, the 
electric lamps or groups of such lamps are fed by 
the secondary coil or coils of an induction apparatus 
placed there. The primary coils of all the induction 
apparatus are in the common circuit of one main- 
lead, which is in connection with a battery or a 
magneto-electric machine placed in some suitable 
situation. The size and length of the primary and 
secondary coils of each induction apparatus is deter- 
mined according to the number of lamps at each 
point, where the secondary current shall supply the 
electric lighting." 

The employment of induction coils for the distri- E. Edwards & 
bution of light, heat, and power was patented in 
England in the same year by Edmund Edwards and 
Alphonse Normandy. Among other matter in this 
patent there is as follows : 

" At or near every point where it is required that 
a light shall be produced, we arrange a coil (or 
series of coils) of insulated metallic wire or ribbon 
(preferably surrounding a bar or wires of soft iron), 
through which coil or coils the current from the 
principal wire first described can be passed when 
desired, or cut off by means of a key or lever. Bound, 
or adjacent to, each coil of insulated wire described, 
we form one or more secondary coils of insulated 
metallic wire, or ribbon, arranged so that the passage 
of the rapidly intermittent current of electricity, as 








described, through the primary coil or coils, generates 
a corresponding current of electricity in each of the 
secondary coils. 

In the same year, Strumbo had also constructed a 
secondary generator like that of Gaulard, and a de- 
scription of it was contained in the newspaper ' Le 
Monde/ of 24th October, 1878. It is of note in this 
apparatus, which we have illustrated in Fig. 13, that 

FIG. 18. 

the primary and secondary wires were wound side 
by side, and that both coils had the same relative 
position to the iron core. 

Harrison also, in the same year, took out a patent 
having the same object as his of the year 1857. Both 
patents proposed the connection of induction coils in 
series. This is especially clearly mentioned in the 


latter of these, as there he says that both induction 
coils are put in circuit at intervals along the main- 
lead, or primary circuit, so that one or more coils are 
near the places where lamps are to be fed. 

We find in Meritens' English patent, No. 5257, of Meritens, 
the year 1878, the series connection of primary coils 
in the dynamo-circuit also described. 

Meritens intended to employ, in place of the many 
separately insulated circuits of the alternating dynamos 
of that time, only a single circuit, fed from one large 
or several smaller dynamos. A large number of in- 
duction coils connected in series, were to have been 
distributed in the different districts of a city. Besides 
this, Meritens made a combination of the secondary 
coils, so that he was in a position to produce currents 
and potentials of various dimensions. 

"We now come to an inventor, who, in his time, Fuller, 1878. 
exercised a great influence upon electric lighting by 
means of transformers, and whose system was in 
every way a great advance on those of his foregoers. 
This man was named Jim Billings Fuller. He began 
to study electric lighting in his laboratory at Brook- 
lyn in the year 1874, giving his whole energy for 
this object. Fuller's system of current distribution 
was first patented in America in the year 1878. The 
patent No. is 210,317, of 26th November, 1878. His 
apparatus is represented in Fig. 14. It consisted of 
an induction coil on which an electric lamp was 
mounted, to all appearances a Jablochkoff candle. 
The induction coil, to which we shall return later on, 
was built in the form of two horseshoe magnets 

c 2 



FIG, 14. 

joined together, and having consequent poles at the 
small coils in the middle, after the manner of the 
magnets of a Gramme machine. The four large 
coils are the primary or ex- 
citing, the four small coils on 
the poles of the double mag- 
nets are the secondary coils. 

The lever MN was of iron, 
and served to weaken the 
effects of induction, inas- 
much as it formed a magnetic 
short circuit. Here we find 
for the first time the employ- 
ment of a regulating device. 
Fig. 15 illustrates the method 
of connection.* As already 
mentioned, Fuller succeeded 
in setting aside many of the 
defects which were adhered 
to in the many very badly 
constructed transformers of 
his predecessors. While he was busy carrying his 
invention into practice, he became a sacrifice to his 
over-great activity, and on the 15th February, 1879, he 
was taken away by illness. Only a few hours before 
his death, he called his foreman to himself, and ex- 
plained to him the principles of his system. After 
ending his explanations, he asked him if he had 
understood all that he had said, and, on receiving 
an answer from him that he had, he smiled con- 

* See also Scientific American,' 5th April, 1879, p. 212. 



tentedly, and a few moments later lie ended a useful 
life, which had given so much promise of good results. 

In the year 1880 Edward Henry Gordon took out E. H. Goni< 

* J 1 OOA 

the English patent No. 41,826. Gordon had con- 
structed an electric lamp based on the fact that when 


FIG 15. 

a current of sufficient electromotive force was passed 
over the space between two balls of platinum or plat- 
inum iridium, the balls were rendered glowing white. 
These balls were suspended by thin platinum wire, or 
the supports were of platinum, serving also to carry 


the current. For the production of overspringing 
sparks, it is well known that a great difference of 
potential is necessary, so Gordon was' obliged to 
have recourse to induction coils, which he intended 
to excite by means of magneto-electric machines, or 
alternating current dynamos. In his patent he de- 
scribes how this idea should be carried out, and he 
actually did feed two lamps of 50 c.p., or one of 100 
c.p. The apparatus is described as follows : u The 
primary consists of a bundle of iron wire 1*3 inch 
diameter, and 18 inches long. Three layers of insu- 
lated wire 0*08 inch in diameter are wound on it. 
The secondary is wound on an insulating tube, and 
consists of about two-thirds of a mile of wire ' 0075 
inch diameter, covered four times with silk. It is 
wound in 60 discs." "There are three binding 


screws, one at each end and one in the centre, so that 
the whole coil, or either half separately, can be used 
for one lamp." 

We do not find in Gordon's patent the slightest 
indication which would justify us in ascribing to him 
the invention of a system of distribution by trans- 
formers as known at the present day, but, on the 
contrary, it is clearly shown that the fundamental 
conditions of such a system of distribution were un- 
known to him, for he laid the chief weight upon 
connecting the induction coils in series, and on the 
production of high electromotive force necessary for 
his lamp. Over and above this, he was of opinion, 
as he stated prominently, that the more advantageous 
kind of dynamo was one such as that of de Meritens, 


having many coils of thin wire, which, were connected 
to separately insulated leads. 

Let us look back upon the inventions which, were 
made in the domain of electric lighting by trans- 
formers from the time of Faraday's discovery of 
induction up to the year 1880. There we see that 
three distinct characteristics were possessed by all 
the systems invented up to that year. These three 
characteristics lay in the construction, the ratio of 
transformation, and th v e method of employing the 
transformers. Single transformers, with two or more 
poles, were used. The ratio was either 1 : 1, in which 
case the induction coil is really not a transformer, or 
it was from a low to a high electromotive force ; but 
nowhere do we find that currents of high electro- 
motive force were converted into those of low 
electromotive force. The idea in the use of trans- 
formers was that of division, not that of distribution 
of electric energy. The difference between division 
and distribution of electrical energy is, in the main, 
as follows. By a division of electrical energy it is 
meant that a fixed amount of produced energy is 
divided into pre-determined parts of a certain 
number and size, while it remains indifferent, as far 
as the total energy is concerned, in what manner and 
how many of these parts are usefully employed. By 
distribution of electrical energy it is meant, on the 
other hand, that the energy produced is variable 
according to the variable requirements of con- 
sumption, the maximum requirement being pre- 
determined from the number and size of the local 


requirements, which also vary relatively to one 
another. Of the last of these systems there is no 
indication in any of the inventions of induction coils 
up to this date. 

If we seek for the cause of these characteristics, 
we find that the reason why transformers with two 
or more poles were constructed is, that the electricians 
of those days either did not know or did not under- 
stand the principles on which a proper transformer 
should be constructed. With them the idea of a 
magnetic pole acting on a wire near it was always 
present, while they entirely overlooked the fact that 
the electro-magnetic force, not the pole, produced 
the electromotive force in the wire. On account of 
this they were of opinion that free poles in a trans- 
former were not only not a drawback, but, on the 
other hand, a distinct advantage. 

We find that Fuller especially held this view. 
He sought not only to have in his apparatus two 
simple poles, but double poles, and indeed he 
patented this arrangement of his transformer. The 
first claim of his patent reads thus : 

" The double electro-magnet herein described, the 
main coils of which are included in the circuit of a 
main conductor from a generator of alternating 
electric currents, producing in said magnet conse- 
quent magnetic poles, as shown, and around which 
poles are coiled helices of wire for receiving the 
currents induced by the polar changes, said helices 
being included in the local circuit with the lamp." 

We must bear in mind that, as far as the ratio and 


idea of employment of a transformer are concerned, 
the problem at that time was quite another to what 
it is now. At present the transformer serves princi- 
pally to render possible the carrying of the current 
to a great distance economically. The electricians 
of those days were not so far advanced as to be able 
to run arc lamps independently of one another on the 
same circuit, and this they held to be quite impos- 
sible, whether the lamps were connected in parallel 
or series. That apparatus was thought to be good 
which allowed separately insulated currents to be 
led from one source of current, each separate circuit 
going to feed a single lamp. The chief reason for 
this view lay in the fact that the extinguishing of 
all the lamps in one circuit could easily take place 
through the fault of one of them. At that time, 
when an arc lamp was cut out of circuit, it was 
replaced by a fixed resistance, instead of which it 
was thought that induction coils would have suited 
well. It may be casually mentioned that owing 
to this fact too sanguine hopes of the solution 
of the problem of independent working of lamps 
were aroused, through a want of sufficient know- 
ledge of the laws of induction. There have also 
been apparatus other than induction coils used for 
the purpose of making the points of consumption 
independent of one another. We can only now 
recall the patent of Jablochkoff, No. 1638, which 
is based on the principle of connecting condensers 
into branches of a quickly alternating main current, 
from which arc lamps, &c., were fed; also a like 



arrangement by Avernarius (Figs. 16 and 17), with 
the use of secondary batteries, which were to be em- 
ployed for either parallel or series connection.* 

FIG. 16. 

FIG. 17. 

There were no transformers in those days which, 
in the present sense of the word " transformer," con- 
vert high electromotive force to low to suit the 
consumers. On the contrary the apparatus, which 
was then used in electric lighting plant, was such as 
converted low into high electromotive force, or such 
that the ratio was 1 : 1, or nearly so, according as it 
was determined by the connection in series of the 
primary coils, and the difference of potential at the 
consumption devices; for example, the induction 
coils of B. Ruhmkorff, Jablochkoff, and Gordon. 

* Avernarius, Centralblatt fur Elektrotechnik, vol. iii. p. 323. 


When, however, the term high electromotive force 
is met with in descriptions of the apparatus of that 
time, it must be taken to mean a great difference of 
potential between the terminals of the dynamo, not 
between the primary terminals of the transformers. 
Take, for instance, 100 transformers connected in 
series, run with a difference of potential at the 
dynamo of 1000 volts, although it was not known at 
that time how to produce so high an electromotive 
force, still this would give across the primary ter- 
minals of each transformer the modest difference of 
potential of 10 volts. In this way the difference of 
potential at the generator was determined by the 
number of transformers in series. This system had 
plainly the great disadvantage, that no matter how 
tortuous a path the lead must follow, it had to pass 
through the primary coils of all the transformers, and 
the principles of a proper system of distribution were 
not present. 

With the invention of the incandescent lamp the 
activity of inventors was given quite another direc- 
tion. The systems of electric lighting up to this 
time were not sufficiently advanced to permit even 
of a division* of the electric light, that is, the ability 
to feed even a small number of lamps from one 
generater. We shall only mention this invention 
so far as it helps to further the history of the trans- 

Gramme made the earliest arc lamp that could be 
employed alone; then followed Jablochkoff, as the 

* At that time a customary and very characteristic expression. 


first who carried out practically, and with good results, 
the use of arc lamps in series or in parallel arc 
with condensers. Siemens and Halske then replaced 
the Jablochkoff candles with their differential lamp, 
which, although not offering an opportunity for a good 
division of light, was unexcelled in construction and 
manufacture, pointing out the way for further pro- 
gress in arc lighting. This class of lighting was 
brought nearly as far forward as it is to-day by the in- 
troduction of continuous cur rents for this use by Brush. 
With the invention of the glow lamp quite other 
aims were placed in the foreground for the electrical 
world. The incandescent lamp did not possess that 
unsteadiness of light which, with arc lamps, gave so 
much trouble to electricians. The prominent 
qualities of the glow lamp offered opportunity for 
the solution of a problem, such as gas had already 
solved half-a-century earlier, namely, the distribution 
of the electric light, or, more properly, of the electric 
current. For this, the already known and generally 
employed methods of connection were no longer 
sufficient. Edison was the first who demonstrated 
that the series method of connection was not suitable 
for glow lamps ; at the same time he showed the ad- 
vantages of parallel connection, coming forward with 
a thoroughly well thought and worked out system of 
distribution. By this means the change was made, 
and, from this time onward, all inventors were obliged 
to suit their systems to the demand, that each point 
of consumption must remain undisturbed by the 
variations of current which take place in the circuit. 


Marcell Deprez has laid down in a work of his,* 
the laws which make it possible to hold the points of 
consumption of electric energy independent of one 
another, and, excepting some inexactnesses which 
crept into his representation, these laws have been 
almost all carried out in practice since that time. 

The system of direct distribution to glow lamps 
had the one well-known serious drawback, viz. that 
it only allowed of limited employment, because the 
cost of tbe leads, with equal loss of energy, increased 
with the square of the distance from the source of 

It was therefore obligatory, in order to carry the 
current economically to greater distances, to seek 
new means and ways, without rendering inefficient 
the only practical system of connecting incandescent 
lamps in parallel. The experience which had already 
been gained in the economical carrying of high 
tension currents with arc lamps in series, pointed out 
that high tension currents should be used, and that 
in the secondary circuits of transformers fed by such 
a current, consuming devices could be connected as 
might be desired. 

Haitzema Enuma, in the year 1881, was the first H. Enuma, 
to go in this direction, and took out a patent for the 1J 
feeding of glow lamps by means of transformers. 

He followed the principle of making each 
secondary circuit and each point of consumption 
independent. The means to this purpose which he 
thought to employ were not practical, and did not at 

* Comptes Bendues, 1881, p. 872. 


all differ in substance from those of his predecessors. 
His system is remarkable for his method of connecting 
the induction coils in the main lead, i.e. in series, 
using the secondary currents from these coils to 
excite other coils from which tertiary currents were 
received, and these again were further used to excite 
quaternary currents, and so on. This procedure 
stands on a level with that of the famed dynamo- 
electric chain of Siemens and Halske, of which it has 
been asked, " To what purpose ? " 

The peculiarities of the system of Haitzema Enuma 
become evident from the following extract from his 
patent : 

" Solche (namlich die bekaunten) Induktionsrollen 
werden in den Hauptstromkreis uberall eingeschaltet, 
wo der Strom abgezweigt (!) werden soil ; und durch 
diese Einrichtung erhalt zuletzt jede elektrische 
Lampe, oder jeder durch Elektrizitat in Betrieb 
gesetzte Apparat seinen eigenen Strom." 

Haitzema Enuma had intended, so far as this shows, 
to connect the primary, secondary, tertiary, &c., coils 
in series, and the main lead being a closed circuit, the 
ends were taken to earth. The ends of the circuits of 
the secondary, tertiary, and further induced currents, 
were also connected together, or to earth. 

Gauiard and The first who came forward with an industrial 

' employment of the series system were Gauiard and 

Gibbs, who, in the year 1883, placed before the public 

an installation of electric lighting in the Koyal 

Aquarium in London. 

There were two such apparatus as shown in Fig. 18, 




FIG. 19. 

which were connected in series, and excited with 
13 amperes from a Siemens' alternating current 
dynamo. The apparatus had the following construc- 
tion : The induction coils, a section of one of which 
is shown in Fig. 19, had three layers of primary wire, 
and the secondary was wound in four divisions, the 
ends of the wires of the divisions being led to a com- 
mutator. Fig. 20 shows this commutator placed in 
the middle of four induction 
coils. The ends of the secon- 
dary wires were connected to 
eight terminals on the upper 
plate of the apparatus, from 
which the current could be 
led away from each pair, or 
combined at will. By aid of 
the commutator, the number of 
coils in circuit could be altered 
as desired. On the lower 
plate there was a second com- 
mutator, which served the 
same purpose for the primary circuit. 

The core of the apparatus consisted of bars of 
insulated iron, and by means of a rack could be 
raised or lowered in the coils for the regulation of 
the current. Both of these arrangements had been 
already long known. 

In the same year another installation for the 
lighting of some stations on the Metropolitan Kail- 
way was taken in hand and carried out. 

The source of current was a Siemens' alternating 


FIG 20. 


current dynamo of type Wo, which was excited by a 
continuous current machine. The potential was 
supposed to be 1500 volts and the current 11 3 
amperes. The main lead connecting the transformers 
in series was of 7 wires of 1 5 mm. diameter, and 
was 22*9 kilometres long, having a resistance of 
30 ohms. Three stations were supplied. At Edge- 
ware Road twelve coils, with their secondary coils in 
parallel, fed 30 glow lamps ; and other four coils, also 
in parallel, fed two Jablochkoff candles. In Aldgate 
two coils supplied one arc lamp, and twelve more 
coils 35 glow lamps, each of 20 c.p. and three of 
40 c.p. At Notting Hill there were 22 glow lamps 
and one arc lamp. In this last installation coils 
were employed with their coils aranged after a 
somewhat different manner. On a pasteboard or 
wooden cylinder of about 50 cm. in height a cable 
was coiled in layers. 

The interior of this cable consisted of a 4 mm. 
copper wire well insulated with paraffined cotton, 
FIG. 21. anc ^ around this, parallel to its axis, lay 
6 cables or cords, each consisting of 
12 wires, also insulated with paraffined 
cotton (Fig. 21). The wire of 4 mm. 
formed the inductor through which 
the primary current was passed. The 
six cables, each of twelve strands, formed the induced 
portion of the apparatus, and the ends were con- 
nected to a commutator, so that they could be used 
either in parallel or series. 

The methods of construction and connection used 


in these attempts by Gaulard and Gibbs did not 
differ in principle from those of their predecessors. 
Gaulard and Gibbs also employed in these trials 
bi-polar induction apparatus. The efficiency of such 
apparatus can only be comparatively small, because 
the effects of magnetisation, and therefore of induc- 
tion, are weakened to a great extent by the lines of 
force having to pass for the greatest part of their 
path through air instead 'of iron. Taking another 
view of such apparatus, as they have a ratio of trans- 
formation of 1 : 1, they must, with the employment 
of high potential, be connected in series. 

Undoubtedly Messrs. Gaulard and Gibbs have in 
their time claimed certain things as new and of their 
own invention, namely, the arrangement of several 
separate induction coils together, the placing of the 
coils next to one another, and the winding of the 
wires parallel. These claims, however, have been 
condemned from all sides as unjustified. The em- 
ployment of several coils has already been mentioned 
as patented by the brothers Bright on 21st October, 
1852, and was again later on discovered by Poggen- 
dorf, Ruhmkorff, Foucault, and others. We have 
also shown, on page 11, that the placing of the coils 
next one another had likewise been invented by 
the same men 30 years earlier. The symmetrical 
arrangement of both coils, the primary and secondary, 
had also already been used. (See page 18.) 

But when, in spite of all this, we find Mr. J. K. 
Mackenzie* maintaining that the Fuller transformer 
* The ' Electrical Engineer,' 17th Feb., 1888. 

D 2 


was non-polar, and further, that the following im- 
provements must be ascribed to Messrs. Gaulard 
and Gibbs, viz. : 

1. The reduction of the primary and secondary 
wire-resistance to a minimum. 

2. The attainment of the greatest possible coefficient 
of induction with the lightest apparatus. 

3. The symmetrical arrangement of both coils. 

4. The proportioning of the coils, so that the 
weight of metal in each is the same. 

Seeing this, it must be thought that this gentle- 
man either does or will not, understand the subject. 
Then if Gaulard has succeeded with his apparatus 
in obtaining some advantages as proposed in the 
above-mentioned clauses, Nos. 1 and 2, these advan- 
tages can be obtained to a much higher degree 
with non-polar transformers. This has been proven 
by Prof. Ferraris.* 

The improvements mentioned under Nos. 3 and 
4 are only to be attained with bi-polar transformers 
after difficult and otherwise disadvantageous arrange- 
ments ; for instance, the combination of the primary 
and secondary wires in a common cable, or, when the 
coils consist of ribbon wire, by the winding of the 
one inside the other. With non-polar transformers 
these improvements are already inherent. The 
Fuller transformer was just as much without poles 
as two horseshoe magnets are, with their like poles 
laid together. 

In all these systems with series connection of the 

* La 'Lumiere electrique," fol. xvii., p. 145-148, 1885. 


transformers, the intensity of the current in the 
primary circuit must be held constant in order that 
it may be possible for the induction apparatus to 
maintain the secondary electromotive force constant. 
Notwithstanding this, constancy was not attained, 
but only one cause of the variations annulled. 
Another cause of the variations of the difference of 
potential at the secondary terminals of the coil still 
remained ; this was the loss of potential due to 
resistance and self-induction, which increased with 
the load. The electromotive force of the secondary, 
and therefore of the primary coils, accordingly 
increases as the current in the secondary decreases. 
When no secondary current is flowing, the electro- 
motive force in the primary and secondary coils is a 
maximum. We have consequently this disproportion 
that the smaller the output of the apparatus the 
greater the energy consumed. With the secondary 
circuit open and a constant exciting current, the 
energy used could be as much as ten times as great 
as under full load. 

The disadvantages of this system are apparent ; 
for, putting aside the loss of energy arising from the 
disproportion between produced and consumed 
energy, each change of load on the secondary circuit 
exerted a great influence on the primary circuit, and 
again on the secondary circuits of the other coils in 
the main circuit. 

All the transformer systems already described 
were intended, as we see, for subdividing the current, 
and as fitting therefor we find the series method of 


connection universally brought forward. With this 
method, owing to a rise in electromotive force which 
was dangerous to the lamps, &c., when only a part 
of those in the secondary circuit were extinguished, 
it was compulsory either to run the induction coil 
fully loaded or quite empty. Thus, when the num- 
ber of lamps or other devices in use was varied, a 
regulation of the current strength and uniform 
working was either quite impossible, or only partly 
possible by unreliable and incomplete mechanical 
means. On this account no one succeeded with this 
method in carrying out a rational distribution of 
current by means of induction coils such as are re- 
quired by the widespread demands for electric 
current from a central station. 

The first to point out the disadvantages of the 
series method of connection was Eankine Kennedy, 
who had devoted himself wholly to the study of in- 
duction apparatus. These disadvantages he published 
in an article in the " Electrical Review " of 9th June, 
1883. At the end of this article we find the inter- 
esting statement that transformers, when not 
connected in the primary circuit in series, as had 
been usual till then, but in parallel, form a self-regu- 
lating system of current distribution. Kankine 
Kennedy expresses this in the following words: 
" In parallel arc, however, the secondary generator 
is a beautiful self-governing system of distribution." 
At the same time, however, his article affords proof 
that the author then possessed only a limited com- 
prehension of the physical facts concerned, because 


he maintained, for instance, that the introduction of 
an induced counter electromotive-force in the circuit 
of an alternating current dynamo might constitute a 
means of regulation without loss of energy ; however, 
it might be allowed, that he meant by these words 
one of these elements which must be present in a 
really rational system of distribution with the use of 
transformers, if it were not the case that at that time 
he was not aware both of the properties of trans- 
formers suiting them for such a connection as well as 
those which make them self-regulating in a system 
of distribution. Above all this he had at that time 
never thought of a transformer in the sense, the word 
is used to-day, that i*, as an induction apparatus, 
which converts high into low tension currents. This 
is quite clear, as is seen from the end of the sentence 
before cited, as he says, " But what about the size of 
conductors for such a system? Prodigious!" Kennedy 
thought to all appearance that the parallel connec- 
tion of transformers made possible self-regulation in 
the same manner as the simple direct parallel con- 
nection of incandescent lamps. While at the same 
time he imagined that on account of the small re- 
sistance of each coil the resistance of the net of leads 
must nearly vanish, therefore he concluded that the 
parallel connection of such induction apparatus as he 
had in his mind's eye was impracticable. 

The apprehension of Kennedy's ideas, as we have 
here stated, finds direct confirmation from the leading 
article in the " Electrical Keview " of 9th June, 1883. 
At the end of this leader the editors say, that " Mr. 


Kennedy's apparatus is an induction coil pure and 
simple." "Messrs. Gaulard and Gibbs will scarcely 
deny, nor can they deny, that the action of this par- 
ticular construction of the coil is identical with that 
of his." In this sentence it is distinctly stated that 
the construction of Kennedy's induction apparatus is 
identical with that of Gaulard and Gibbs'. Kennedy 
accepted this statement in silence ; if it had been 
otherwise, he would have protested in his next ap- 
pearance in print. 

In order to make possible the connection of trans- 
formers in parallel, the advantages of which it may 
be said Kennedy had augured, there was still much 
wanting. Above all there was wanting the idea of a 
transformer as meant at present, and an exact know- 
ledge of its action. F. Geraldy has expressed 
himself very suitably upon this point in the intro- 
duction to his report upon the trials made with the 
system of Messrs. Gaulard and Gibbs.* 

"La distribution de 1'e'lectricite comporte la solu- 
tion d'un grand nombre de problemes. II ne suffit 
pas de se decider en principe et lorsqu'on a choisi la 
distribution en quantite (en supposant meme, que 
Fun des precedes puisse eire applique d'une facon 
exclusive, ce qui n'est pas certain), lorsqu'on a trouve 
le moyen de regler le generateur et les recepteurs 
conformernent au mode choisi, il reste encore a lever 
quantite de difficultes, a creer et disposer beaucoup 
d'organes auxiliaires." Geraldy explained distinctly 
that it was not sufficient to determine only the 
* La * Lumiere electrique,' vol. x. p. 496, 1883. 


method of connection, but there were still a consider- 
able number of obstacles to be surmounted before 
the object could be attained. 

It has been a costly lesson, before the properties 
of transformers were known, w f hich make them form a 
self-regulating system. Even in the year 1884 do 
we still find Messrs. Gaulard and Gibbs on the same 
false track as previously. It was in the Turin Ex- 
hibition where Messrs. Gaulard and Gibbs carried 
out their system upon a large scale, and where they 
also succeeded in gaining the interest of technical 
circles, and arousing general attention. 

The transformers installed by Messrs. Gaulard and 
Gibbs in the Turin Exhibition were protected by the 
German patent, No. 28947, and this time again their 
transformers were wound with equal primary and 
secondary coils. The construction of the apparatus, 
as already explained, made it a necessary condition 
that the transformers be connected in series, because 
only by this means could the high tension current 
be utilised. It was a necessary corollary of this 
method of connection that the converting of the high 
potential of the primary circuit into low potential, 
was performed, not by the ratio of the number of 
turns in the coils of the transformers, but in a certain 
manner by the subdivision of the electromotive force 
in the circuit. 

The special construction of the transformers used 
in the Turin Exhibition differed from the older 
apparatus in so far that both coils were formed of 
stamped out circular copper discs, which were 


soldered together by projecting teetb. Tbe insula- 
tion was made of stamped-out paper discs. Botb 
spirals were wound between one another. The 
building up of such coils was effected in the follow- 
ing manner (see Fig. 22A) : A red copper disc was 
first placed on the core, then insulation, upon this a 
black copper disc, then again a red copper disc, and 
so on. Like colours of copper discs were then 
soldered together at the projecting teeth. In this 

FIG. 22. 

manner there were produced two spirals running 
parallel with one another, there only being one layer 
of coils. The employment of such ribbon conductors 
had some advantages, namely, good use of the space 
at disposal for coils, and rapid cooling through the 
projecting teeth. They had, also, disadvantages, the 
chief of which was, that the conductors were of bare 
metal, so that a fault in insulation could easily occur. 



In fact, several 
faults in the trans- 
formers in Turin 
did arise from this 
cause, the action of 
the coils being dis- 
turbed. Further 
attempts with simi- 
lar coils were made, 
the station houses 
of Turin, Venaria, 
and Lanzo being lit 
for five consecutive 
hours. The circuit 
was about 80 kilo- 
metres long, the 
main lead being of 
chrombronze wire 
of 3 '7 mm. di- 
ameter. At Turin 
there were 34 
Edison lamps of 
16 c.p. each, and 
a sun arc lamp ; at 
Lanzo there were 
nine Bernstein 
lamps, 16 Swan 
lamps, a sun arc 
lamp, and two 
Siemens' arc lamps. 
In the exhibition 


itself, there were nine Bernstein lamps, nine Swan 
lamps, and a sun arc lamp. In the Figaro Kiosk 
nine Swan lamps were fed from a small transformer. 

As already related, the trials of Messrs. Gaulard 
and Gibbs' system at Turin had aroused in the 
widest circles the liveliest interest, and, consequently, 
the errors of the system soon became public. Thus 
we find in the technical literature of that time 
influential voices raised against the system, and 
pointing out its disadvantages. 

Among others, Prof. Colombo read a paper during 
the course of the National Exhibition at Turin, the 
subject being the system of Gaulard and Gibbs. 
While doing sufficient justice to the good points of 
the system, he also said that although it solved the 
problem of carrying the electric current to great 
distances, it was in no way what it was represented 
to be, and what it should be : a system of distribution 
allowing the electric current from a distant central 
station to be led to meet the demands of any kind 
of consumer without any one of these interfering 
with the supply of current to any other. He 
characterised these drawbacks sharply, and very 
suitably, by the remark, that in the Gaulard and 
Gibbs system, each consumer drew properly his 
supply of current from his transformer, and not from 
a common network of leads always self-regulating, 
as is the case in every large installation with 
continuous currents. Prof. Colombo satisfied him- 
self with this reference to its disadvantages, mention- 
ing also what should be striven after to make the 


system a perfect one, saying that the ideal electric 
lead system was one combining the advantages of 
the Edison central-station with that of Gaulard and 

Prof. Colombo confined himself to these hints, and 
he must acknowledge that the means leading to the 
attainment of this purpose remained still to be found 

The reproduction of this lecture by Prof. Colombo 
is placed before an article by Deprez in " La Lumiere 
electrique," * in which latter the system of Gaulard 
and Gibbs is strongly criticised. Deprez showed that 
that system can have no claim to be new. He 
points also to the wants of the system, especially 
that of self-regulation, stating that the means remain 
still to be discovered, which would make possible 
the self-regulation of a system of distribution with 
transformers. He also says that Gaulard's system 
of distribution had not solved this problem, and 
therefore could not be held to be practically useful. 

We find the same view represented in an article 
by H. Koux,f where he points to the enormous 
fluctuations which take place when the resistance in 
the secondary circuit is altered. Some of the figures 
vouching for his opinion we shall now reproduce. 
They were taken by M. Pietro Uzel, in Turin, in an 
observational way 4 

The observations are only quoted so far that the 

* La ' Lumiere electrique,' vol. xiv. p. 45. 

t ' Electricien,' 7th March, 1885. 

J 'Natura,' 25th January, 1885, p. 60. 



Watts A I at the secondary terminals are still in- 
creasing; were they continued further the damning 
fact would reveal itself that as the power put in 
increased, the power given out would approach zero. 
Taking account of these fluctuations, it is not 
possible to see how, as Mr. Eoux says with justice, 
a distribution of current by this system can be made 
in an efficient manner. Mr. Gaulard in his reply, 
virtually assents to this article, but adds, that these 




Primary Circuit. 


Secondary Circuit. 







I A 















































































variations could be prevented, if the cores of the 
transformers be shifted either by hand or auto- 
matically. Both methods would be expensive, and, 
besides, the automatic regulation would be unreliable. 

It was at once recognised by all those interested 
in the subject, that this system made possible a sub- 
division, but by no means a distribution of current. 

Before proceeding further with the history of the 
development of the transformer, let us for a little 


while take up the question, what conditions are 
necessary for a practical and rational system of 
current distribution by means of transformers. As we 
have already explained in another part of this paper, 
the method of parallel connection, i.e., a system in 
which the difference of potential is held constant, is 
alone suitable. Deprez maintained in his time that the 
difference of potential between the terminals of the 
source of current must be kept constant. Should the 
distribution be made on this principle, the resistance 
of the network of leads must be very small, in order 
that with full load only a very small loss of electro- 
motive force may take place in the leads. In the 
indirect system of current distribution, consequently, 
the tension at the secondary terminals of the trans- 
formers must also be maintained constant. 

The question is now before us, In what manner 
must the primary electromotive force vary to effect 
this ? Consider an iron core, having on two different 
parts round it, two rings of wire. This iron core may 
now be magnetised by bringing near to it in the 
line of its axis a permanent magnet. On drawing 
the latter quickly away, an electromotive force will 
be momentarily produced in both the wire rings, 
and the electromotive force will be proportional to 
the number of the disappearing lines of force. This 
number, in consequence of the dispersion of the lines 
of force, will be very different at different parts of 
the magnetised core. The induced electromotive 
forces in the windings of the wire will also be dif- 
ferent. The equality of these electromotive forces, 


which is so important, can only be attained if all the 
windings are in relatively the same position with 
regard to the magnetic field. The circuits of both 
coils being closed, the one having a current flowing 
through it, the other through a suitable resistance, 
besides the condition mentioned in the last sentence, 
another must be fulfilled ; this is, the internal resist- 
ance must be practically zero, i. e. the difference of 
potential between the terminals shall equal to all 
intents and purposes the total electromotive force. 

We have now to examine how far the already 
observed constructions of transformers fulfilled these 
demands. A transformer in which the windings lie 
relatively in the same position to the magnetic field 
can quite well be bi -polar. All that is necessary for 
this is that the coils be wound on to the core next 
to one another; this is most simply managed in a 
transformer having a ratio of 1:1. This law was 
first determined by Maxwell. The apparatus of 
Strumbo shows such a method of winding already 
carried out. 

Thus it may be seen that of bi-polar transformers, 
those which, with regard to the constancy of the 
secondary tension, are most suitable, are quite use- 
less on account of their ratio being 1 : 1, although 
they are destined for the series method of connection. 

The connection of proper transformers in parallel 
can only be made with such apparatus as, not- 
withstanding their ratio of transformation, possess 
windings having the same relative position to the 
magnetic field this is only the case with non-polar 


transformers. Besides this quality of non-polar trans- 
formers, their magnetic resistance is so low that the 
condition of very low internal resistance is easily 

The following conditions of a self-regulating and 
economical system of current distribution with 
transformers result, therefore, from the foregoing 
explanations : 

1. The generator of current must give a great 
difference of potential as constant as possible at the 
terminals of the transformers, and also independent 
of the number fed. 

2. The transformers must convert the current of 
high electromotive force into a current of such 
electromotive force as may be desired. The trans- 
formers must have a closed magnetic circuit (that is, 
they must be poleless), in order that all the primary 
and secondary turns shall possess, relatively to the 
magnetic field, a like position, also in order that the 
resistances of the primary and secondary coils shall 
be so small that they cause practically no loss of 
electromotive force. 

Throught he fulfilment of both these conditions, it 
is rendered possible to maintain the secondary tension 
constant by maintaining the primary tension constant, 
indifferently whether it is regulated automatically 
or by hand. To suit this, the transformers must also 
be arranged into distributive stations of the second 
order, and derived in parallel from the main leads. 

In May, 1885, a system of current distribution 
meeting all the just-mentioned requirements was mi 


publicly brought out, giving an illustration of a 
truly self-regulating system of current distribution, 
This was the system of Zipernowsky, Deri, and 

The first two patents concerning this system date 
from 18th February, 1885, and are entitled, "Im^ 
provements in the means for the regulation of 
alternating electric currents," No. 34,649, by Carl 
Zipernowsky and Max Deri, of Budapest ; " Improve- 
ments in the distribution of alternating currents," 
No. 33,951, by Max Deri, of Vienna. The third 
patent is dated 6th March, 1885, and is entitled, 
" Improvements in induction apparatus for the pur- 
pose of transforming electric currents," No. 40,414, 
by Carl Zipernowsky, Max Deri, and Otto Titus 
Blathy, of Budapest. 

The system described in these three patents was 
immediately afterwards brought forward in the 
three exhibitions of Budapest, Antwerp, and London 
(Inventions Exhibition), arousing in technical circles 
a general and well-earned attention. 

In the patent documents as well as in the earliest * 
articles in the journals concerning the system, two 
special forms of transformers are described, viz. that 
consisting of an iron core with the wire outside, and, 
secondly, that consisting of copper coils surrounded 
by iron wire. The transformers shown in Figs. 24 
to 28 belong to the last of these classes, that in 
Fig. 23 to the first. The fundamental principle 

* Elektricitatsverteilung aus Centralstationen, System Ziper- 
nowsky-Deri, Centralbl. f. Electrotechnik Bd. VII. S. 422. 



upon which all these transformers are constructed is 
that the subdivisions of the iron core run perpen- 
dicularly to the copper wires. Transformers such as 
are shown in Fig. 25 having a ring-shaped iron core 
wound with copper wire at first employed, later 

FIG. 23. 



the inventors used in preference the form repre- 
sented in Fig. 23. 

In all these forms the principle is generally 
adhered to, that the magnetic resistance and the 

E 2 



exciting power possess for each part of the length of 
the magnetic circuit the same value, and thus the 
formation of poles with the resulting dispersion of 
the lines of force is avoided. 

This system procured for itself universal recogni- 
tion, but especially in the Budapest Exhibition. 

FIG. 24. 

There several exhibits within a radius of 1,300 
metres were lit from a common central station. The 
several circuits were quite independent of one 
another, and lamps could be extinguished or lit in 


FIG. 25. 


FIG. 27. 

I Copper wire. 



any one of them without anywhere producing a 
change in the intensity of the light, which could 
be perceived. 

It was, therefore, in the year 1885 that the prob- 
lem of current distribution by means of transformers 
was solved in a truly practical manner. The ideas 
which led the inventors to this thoroughly success- 
ful solution were then so unknown to practical and 
theoretical electricians, that it was long ere they 

FIG. 29. 
Main Conductor 1 

Main- Conductor 


were understood and appreciated. Even in February, 
1886, such an electrician as Prof. Forbes maintained 
in his Cantor Lectures that the parallel connection 
of transformers was quite impracticable. He believed, 
namely, that a connection such as shown in Fig. 29 
was useless, because the difference of potential at the 
generator diminished from the machine outwards, 
but that a connection such as shown in Fig. 30 must 
be used. According to him, in a direct system of 



distribution each lamp should have a separate lead, 
and having regard to the great number of leads 
which would thus be necessary, he concluded that 
the series method of connection was the right one. 
One would suppose that Prof. Forbes was not aware 
of the weighty disadvantages of this method. How- 
ever, that was not the case. He proposed, that with 
series connection the strength of current should be 
kept constant, and that each transformer should 

FIG. 30. 

have an especial regulating apparatus the raising or 
lowering of the core; which, by the way, is an arrange- 
ment impracticable in a well designed transformer. 
Such a regulating apparatus has lately been made 

" This is," says Prof. Forbes, " the last triumph, 
which after a series of troublesome experiments has 
brought us year after year nearer to the solution of 
the difficulties." " I am not in a position to explain 



here the modus operandi" he says further, " but I 
have seen the apparatus working very satisfactorily." 
This apparatus has up till now not become known. 
The assertion that the troublesome experiments had 
brought us year after year nearer to the solution of 
the difficulties, is quite inappropriate. Just the 

FIG. 31. 







urn [pi 






] C 



3 C 











opposite is the case ; they have taken us year after 
year further away from the solution, until at last all 
was thrown overboard and a new commencement 

Profs. Ruhlrnann* and Essonf also gave vent to 
their opinions against the connection of transformers 

* * Electrical Keview,' vol. xvii. p. 157. 

t ' Elektrotecknische Zeitschrift/ September, 1885. 


in parallel. In a like manner Messrs. Gaulard and 
Gibbs for some time after the Zipernowsky-Deri 
system was known pleaded for their own method of 
connection, until at last they were obliged, on account 
of the unpleasant experiences at the Grosvenor 
Gallery in London, to adopt the system of parallel 
connection, which they then at once employed at 

There were, up till very lately, still many elec- 
tricians who did not perceive the advantages of 
parallel connection, just for the simple reason that 
they were ignorant of the properties of the non-polar 
transformer, suiting the parallel system of connection 
for a rational system of distribution. Especially the 
one property of transformers remained unknown to 
the literature devoted to the subject up to the year 
1885, namely, that in transformers properly con- 
structed the relation between the primary electro- 
motive force and that of the secondary, remains 
unaltered notwithstanding any variations in the 
current taken out ; also that if the primary electro- 
motive force be kept constant the secondary would 
likewise remain constant, provided the transformer 
be connected in parallel. 

It had taken 30 years, until at last the way was 
found leading to the desired result. We have al- 
ready superabundantly explained that this direction 
was essentially different from that taken by all 
electricians until after Gaulard's time ; that not only 
the methods of connection, disposition, and regulation 
of the system, but also the construction of the trans- 


formers themselves had to be quite departed from, 
and apparatus constructed which obeyed totally other 
laws to those of the earlier forms. 

If indeed earlier inventors proposed for other pur- 
poses magnetically-closed induction coils, the fame 
due to the birth of proper non-polar transformers, in 
which the whole of the primary and secondary turns 
have a like position relatively to the magnetic-field, 
first invented, carried out, and combined into a self- 
regulating systen of current distribution, belongs 
undoubtedly to Messrs. Zipernowsky, Deri, and 

It would have been thought that after the direct 
distribution of current to glow-lamps had taken up a 
determined position, it would not have been difficult 
to discover a self-regulating system of distribution 
with transformers. However, the fact shows this was 
not the case, for after the Edison lighting system 
was long known, we find such electricians as Haitzema 
Enuma, Gaulard, and Kennedy, experimenting with 
the series system of connection ; indeed the last of 
these even deters his colleagues from the attempt to 
run transformers in parallel, because he openly held 
the opinion that this method of connection was im- 

We have here the development of current distri- 
bution by means of transformers, as it completed 
itself in Europe. The American electricians how- 
ever, made the matter somewhat easier. They 
quietly waited until the invention gave useful results 
in Europe, and then simply imported it. 


The field to-day belongs to the parallel method of 
connection, and after the installation in the alkali 
works at Aschersleben was destroyed by flooding, 
there only remains a single installation with series 
connection, as far as we know ; this is that which 
was fitted up in Tivoli near Kome in the year 1886. 
This installation however, serves only to feed an in- 
variable number of street-lamps, and can therefore 
have no claim to the designation of an installation 
for the distribution of electric currents by means of 





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MAY 1 9 1978 




APR 14 1933 

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