August 12, 1880] 



NATURE 



355 



The author expressed his indebtednefs to all his colleagues, to 

 Prof. Geikie, to the Hydrographer and officers of the hydro- 

 graphic department, and in a special manner to Sir Wyville 

 Thomson, under v/hose direction and advice all the observations 

 had been conducted. 



CJialleiiger Office, 32, Queen Street, Edinburgh. 



THE J AM IN CANDLE 

 A NEW system in addition to those already prominent in the 

 ■^"^^ extensive field of electric lighting is shortly to be intro- 

 duced into this country in the form of a candle devised by the 

 well-known Trench electrician M. Jamin. This invention brings 

 with it a considerable reputation, and how far this maybe justified 

 we shall probably soon have the opportunity of judging. 



It has not yet had a trial in England, and until this is done 

 we can only rely on the results of experiments, apparently of a 

 not very exiiaustive or conclusive character, w-hich have tahen 

 place in Paris, and which must be accepted with a considerable 

 amount of re^ervation. 



The following I'escription of the new candle is that given by 

 M. Jamin himself in his paper to the French Academy of May 

 31, 1S80:— 



" I have had the honour to submit to the Academy during its 

 sitting of March 17, 1879, the principle of a new electric burner. 



" I have since succeeded in constructing a practical lamp, 

 which I will describe. It rests on a slate base, which can 

 be fixed into the globes or lantern?, according to the require- 

 ments of the decorations, and which supports at the base a 

 gutter of copper, wide, but not very thick, in order to avoid 

 shadows, and at the top is a gutter of soft iron, intended to 

 be magnetised and to attract a movable armature or plate. 

 The alternating current of a Gramme machine passes first through 

 a wire of thin copper folded round the gutter some fifteen or 

 twenty times, and which constitutes the directing circuit. In the 

 middle of this frame and in the same plane are placed the 

 candles or pairs of carbon rods between which the electric arc is 

 to play. There are three, but a larger number can be inserted if 

 the lighting is to be prolonged. Each carbon rod is inserted in 

 a metal socket, in which they stand vertically, point downwards, 

 and are retained in this position by means of a spring. 



" The working offers no difficulties and demands no skill. 

 There is no insulating material between the carbons. Those on 

 the right are fixed and vertical ; those on the left, hang freely 

 from hinges ; the tops of their supports are conected by a small 

 bar, which give s them a movement in common ; the armature is 

 attached by a lever to this bar, which it pushes towards the left 

 by its weight, which brings the carbons together until one of them 

 touches its companion. It is to be remarked that the contact 

 will only be made in one of the candles, the longest, or the one 

 whose points hang nearest together ; that one will be lighted. 



" The electric current, after having traversed the directing 

 circuit, arrives simultaneously at the movable carbons, and can 

 return indiscriminately by the three fixed carbons ; it passes 

 between those which touch, and lights them. Innnediately the 

 magnetism is made the armature is attracted, the three couples 

 of carbons spring apart at the same time, two remaining cold, and 

 the arc being established in the third. As long as there is any 

 matter to burn it continues maintained at the points by the action 

 of the directing current, and necessarily returning to it if any 

 foreign cause should drive it away. When the current stops the 

 armature falls back, and the contact is re-established ; if it passes 

 through again, the carbons are relighted, and spring apart as at 

 first. Thus the lighting is automatic, instantaneous, and renew- 

 able at will. 



" When the first candle is consumed, another must succeed it. 

 For this purpose the left carbon-holder, which remained fixed, 

 is jointed at the top and can be displaced, not in the plane of 

 the frame, but perpendicularly. It is pushed by a spring, R, 

 which tends to force it away, but it is kept vertical by a wire, B, 

 bent round like a hook at its end, and which slides tightly in a 

 receptacle where a spring presses it. When the combustion of 

 the candle has brought the arc up to this point, the wire is 

 melted, the carbon-holder is released, the tw'o carbons spring 

 suddenly apart, and the arc is extinguished, but immediately re- 

 lights in the neighbouring candle. The change is so rapid that 

 the action is hardly jwrceptible, and the other lamps in the same 

 circuit are not at all affected. 



" Besides, it must be remarked that this substitution of a fresh 

 candle for the one consumed only happens every two hours, that 



the wire is only melted at its extremity, that it is sufficient to cut 

 off the point to bend it again and to draw it a httle further from 

 its receptacle, when new carbons are to be inserted, and that it 

 serves for a great number of times. One of the greatest incon- 

 veniences of electric lighting is the possible sudden extinction of 

 one of the lamps, which immediately causes that of the other 

 candles in the same circuit, although they may be in good con- 

 dition. Ours are very little subject to this danger, but it must, 

 however, be foreseen and remedied. For this purpose one of 

 my pupils has devised a system, the description of which 

 would be too long. Its effect is (l) to open, at the moment of 

 accident, a secondary circuit, which continues the current across 

 the faulty candle ; (2) to replace the extinguished lamp by an 

 equal resistance, which leaves the others in the condition in 

 which they were at first. 



" This addition is very important, as it permits of our lighting 

 many or few candles without changing their brilliancy. 



"To sum up, eur lamp contains many essential qualities. It 

 lights and relights itself as often as required ; it only requires 

 one circuit for all the neighbouring candles ; it replaces auto- 

 matically those which are entirely consumed, by new carbons : 

 it employs no insulating material which might alter the colour of 

 the flame ; and it requires no preliminary preparation of the 

 carbons, which considerably diminishes the expense. If at first 

 it underwent, like all others, variations of brilliancy that were 

 owing, not to the construction, but to the defective preparation 

 of the carbons, these variations have disappeared since, thanks 

 to M. Carre, to whom so much is already due, and who has just 

 given to his carbons the necessary solidity." 



In the summer of 187S the writer, in conjunction with Mr. 

 McEniry, carried out a series of experiments with various forms 

 of electric candles for Mr. Robert Sabine ; the result is embodied 

 in his provisional specification of November 27, 1878, part of 

 which runs as follows : — 



" My third improvement in regulating the distance between 

 the carbon electrodes of a regulator or lamp consists in taking 

 advantage of the well-known fact that parallel conductors attract 

 or repel each other according as the currents in them go in the 

 same or in opposite directions. For this purpose I place the 

 carbons vertically side by side, one of them being fixed and the 

 other balanced over a fulcrum or centre. The frames cari7ing 

 the two carbons form portions of tlie common electric circuit in 

 such a way that when the current circulates the parallel portions 

 of the balanced frame (which carries the movable carbon) are 

 deflected and the carbons separated. The degree of deflection 

 of the flame depending upon the current, it follows that, should 

 from any cause the electromotive force in the circuit increase, 

 the frame is thereby deflected more, and the electric arc is 

 correspondingly increased in length, which reduces the current 

 again and maintains the light more steadily than when the 

 carbons are placed immovably side by side without any such 

 adjustment." 



It is presumed by the writer that M. Jamin's paper to the 

 French Academy of March 17, 1879, explaining the principle of 

 his new candle, was the first public notice of it, and it w ill be 

 therefore clearly seen that the part of the apparatus which he 

 claims as particularly his own, viz., the directing frame, is in 

 reality due to Mr. Sabine, and that while giving every credit to 

 M. lamin for independence of thought, it is only in common 

 justice to Mr. Sabine that he should receive the merit of an idea 

 which, in the words of a very flattering notice of the origin of 

 Jamin's candle in a recent number of La Lumicre Electiique, 

 constitutes an elegant appUcation of Ampere's laws. 



Mr. Sabine's arrangement is also of a more simple nature 

 than the candle just described, for it not only regulates the arc 

 but separates the carbons without the aid of magnetism, and 

 this could be as easily accomplished for a combination of three 

 candles as for one. 



It is probable that this latter candle was never constructed 

 beyond the experimental stage, but that it could be put into a 

 very simple and practical form is obvious. 



Having thus shown that the two systems are identical, we will 

 turn our attention to the consideration of the claims of this parti- 

 cular form of candle as now perfected and brought forward by 

 M. Jamin. 



It is questionable whether the surrounding frame of wire is as 

 efficacious as we are led to believe, but that it exerts a certain 

 influence on the electric arc is beyond doubt ; but whether this 

 favours the light or acts detrimentally by blowing and expanding 

 the arc remains to be proved. Again, the fact of burning an 



