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CHAPTER II.

HISTORY OF ELECTRIC LIGHTING.

LIGHTNING is the first and grandest form of electric light. Ordinarily, however, we confine the term to mean artificial electric light. Considered from this point of view, probably the first electric illuminating effects obtained by man were electric sparks produced intentionally or accidentally by frictional electricity. The effects obtained, however, in these very early experiments were so feeble that they are hardly worth considering; and it was not until the first electrical machine was made by Otto von Guericke, about the middle of the seventeenth century, that the sparks produced were sufficiently powerful and frequent to be looked upon as even the germ of the electric light. In fact, the duration of an electric spark being only an almost infinitesimal fraction of a second, it can hardly be considered to be a light of any practical use. Later, however, the frictional electric machine was improved by Newton and others, and numerous experimenters took up the study and development of electricity. One line of work which probably produced an electric light worthy of the name earlier than any other method, and one which has recently assumed particular importance, is the production of light by means of electrical discharges in air or other gases, whether rarefied or not. Intermittent electric sparks are entirely too sudden and temporary, unless the number of sparks is made sufficiently great to be practically equivalent to a continuous discharge.

During the latter part of the seventeenth and early in the eighteenth century numerous experiments were made with discharges in air or rarefied gas.

The record of these may be found in a book entitled PhysicoMechanical Experiments on Various Subjects, containing an Account of Several Surprising Phenomena touching Light and Electricity. By F. Hauksbee, F.R.S. Published in London in 1709.

The above experiments deserve to be considered as being the first production of the electric light in anything like a practical

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way, although heretofore they have been ignored so far as the history of electric lighting is concerned; but the interesting experiments of Tesla and others in connection with electrical discharges might lead us to look upon these very early attempts as being as important as much later experiments which are ordinarily given as the origin of the electric light. Leaving aside, however, the question of what the electric light of the future may be, it is certainly a fact that the electric light of the present day depends essentially upon the use of an electric current of several amperes, or a large fraction of one ampere. Frictional electric machines cannot give any such current; therefore electric lighting of the kind now practiced was an impossibility until some source of electric current was discovered. The first source of this kind was the primary battery, or chemical generator of electricity, invented by Volta in 1800. The voltaic battery was soon taken up and developed by scientific men, and batteries of sufficient power to produce quite strong currents were made by Volta himself and by others. Sir Humphry Davy immediately recognized the great possibilities of the battery for scientific and practical use, and constructed a very large one of 2,000 pairs of plates in 1808. This battery was used by him in various investigations; and in the years of 1809 and 1810 he performed with it the epoch-making experiment of producing a continuous and brilliant electric light, which was practically identical in principle with the arc light of to-day. This experiment is best described in his own. words as follows: "When pieces of charcoal about an inch long and one-sixth of an inch in diameter were brought near each other, within a thirtieth or fortieth part of an inch, a bright spark was produced, and more than half the volume of charcoal became ignited to whiteness; and by withdrawing the points from each other a constant discharge took place through the heated air, in a space equal to at least four inches, producing a most brilliant ascending arch of light."

It should be noted that in the above experiment Davy made use of carbon electrodes, which are the essential elements of the present arc lamp; and carbon is also used for the filament of all practical forms of incandescent lamp. He also noticed the arched form of the electric current between the carbon points, from which form the arc derives its name. This great experiment is unques

tionably the foundation of the present methods of electric lighting; but the use of a voltaic battery as the source of current prevented any extensive introduction of the electric light, on account of the prohibitive expense and trouble of running a battery large enough to give sufficient current. A much more powerful and cheaper source of electrical energy was needed to make the electric light a practical success; therefore little or no progress was made until the discovery by Faraday, in 1831,* of magnetoelectric induction, which was almost immediately followed by the rapid development of the magneto-electric machine, or mechanical generator of electricity, from which has been evolved the modern dynamo-electric machine. The most notable of the first machines. were those of Dal Negro,† Pixii, ‡ Saxton (1833), § and Clarke (1835). These machines were all similar in principle, and consisted essentially of coils or bobbins of copper wire and a permanent magnet, one of which was revolved and the other held stationary. This rotation produced primarily an alternating current in the coils, which was led out by suitable connections. At the suggestion of Ampère,** a commutator was added, in order to obtain a direct current; that is, one flowing in one direction only. These magneto machines were perfected and built on a larger scale by other experimenters.

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The most noteworthy types of these larger machines were the "Alliance machine" and the "Wilde machine." These forms were made of considerable power; that is to say, they were capable of generating currents of several horse-power, and adapted to being used for practical work. The Alliance machine originated with Nollet in 1849, and was improved by Holmes, Masson, Du Moncel, and others; and in 1857 it had been brought up to a fairly perfected condition. In 1863 this machine was applied to lighting the lighthouses of the French coast by electricity. This was probably the first important practical use of the electric light, and is therefore of great interest. About the same time the Wilde machines were also being used to generate current for arc lights; but these for the most part were for experimental or exhibition purposes. These machines, it should be

+ Phil. Mag., July, 1832.
§ Phil. Mag., 1836.

* Experimental Researches, vol. i. p. 25.
* Ann. Chim. Phys., vol. 1. p. 322, 1832.
**Ann. Chim. Phys., li., 76, 1832.

Ibid.

remembered, were up to that time of the magneto type; that is to say, the field magnetism was produced by permanent magnets. The use of electro-magnets, and the principle of self-excitation as applied to the modern dynamo-electric machine, was developed by various workers. In 1845 Wheatstone and Cooke patented the use of electro-magnets instead of permanent magnets, which were, however, to be excited by a current obtained Irom some source outside of the machine itself, being what is now called separately excited. Brett, in 1848, suggested that the permanent magnetism in a magneto machine might be increased by the current of the machine itself. Sinsteden independently made a similar suggestion in 1851. Wilde, in 1863, used a small magneto machine to supply currents to an electromagnet which formed the field magnet of a very much larger generator. In this way he obtained very powerful effects, and made a machine capable, for example, of fusing a copper rod of considerable diameter. The definite and complete invention of the principle of using the current of the machine itself to feed its own field magnet was independently and almost simultaneously announced by Werner Siemens to the Berlin Academy on Jan. 17, 1867, and by Sir Charles Wheatstone to the Royal Society of London on Feb. 14, 1867. This gave to the world the modern dynamo-electric machine, upon which, more than anything else, the great success of electric lighting and almost all the other applications of electricity depends. The next important step in the development of the dynamo was the improvement of the armature, which up to that time had been quite crude. In 1860 Pacinotti designed, and in 1865 published* a description of, a machine having a ring armature with a continuous winding. This is the essential element of the very high efficiency directcurrent generators of the present day. This invention was practically, ignored until it was independently rediscovered by Gramme in 1870.

The invention of Pacinotti had been merely a laboratory experiment, whereas Gramme took up the subject as an engineer, and designed and constructed many successful machines of this type. In 1873 von Hefner-Alteneck applied Gramme's principle of a continuous or closed-coil winding to the shuttle armature invented

* Nuovo Cimento, xix., 378, 1865.

by Werner Siemens in 1856. The Siemens shuttle armature, sometimes called the I armature on account of the form of cross section of its iron core, was at the time of its invention a decided improvement over the bobbin forms of armature then in use in regard to mechanical construction and compactness; but in its magnetic and electrical action it is radically imperfect, principally because it has only a single coil, which produces a very intermittent effect. The Alteneck armature, on the other hand, is wound with a number of coils or sections of wire in different planes, and is therefore continuous and steady in its action, like the Gramme armature. The only difference in principle between these two important types of armature is the fact that the iron core of the Gramme armature is in the form of a ring, while that of the Alteneck armature is a drum or cylinder. In fact, these terms are more commonly employed to designate the two types of armatures than the names of their inventors. Up to that time the history of electric lighting had been the history of the electric generator, because a good source of current had first to be obtained before any real progress could be made in applying electricity to the purpose of lighting. But the dynamo machine having been brought up to a reasonably practical form, it was available to form a solid basis for the astonishingly rapid development of practical electric lighting which then began. At the same time that the dynamo was being improved the problem of producing a satisfactory electric lamp was also being grappled with; but no very successful results had been obtained. Serrin in 1857, and others, had constructed arc lamps, or what were then called "regulators," which consisted. of the electric arc between carbon points such as was produced long before by Davy, with the addition of a clock-work or other mechanism for feeding the carbons together as they burned away.

The incandescent lamp progressed at first even more slowly and imperfectly than the arc lamp. Crude forms of lamps were devised and made by Starr and King in 1845, Staite in 1848, and others; but none of these attempts can be looked upon as anything more than interesting experiments which laid the foundation for further progress. In 1876 there existed fairly satisfactory forms of dynamo machines and of arc lamps, and there

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