Some of the major developments that led to a practical electric incandescent lamp are reviewed in order to gain an appreciation of the work and dedication expended by untold numbers of experimenters. Some efforts will be purposely, as well as inadvertently, left out. However, with the passage of time a more complete and accurate story should result. This cursory effort is a modest beginning toward that end.

Alessandro Volta
The picture of Alessandro Volta (1745-1827), shown to the left, was scanned from Reference (18). Volta was born in the city of Como in northern Italy. He was professor of physics at the University of Pavia. Although static electricity was known prior to Volta's work it was he who introduced a method of obtaining continuous electrical current to the world. This extremely creative invention gave mankind a power source that was of great benefit initially to the scientific community and later to the general community. The invention was the voltaic pile, the forerunner of the storage battery of today. One version of the voltaic battery consisted of stacks of silver and zinc plates separated by paper that had been soaked in salt water. Volta wrote a letter on March 20, 1800 to the Royal Society revealing his discovery and within a short period of time the first battery was constructed in England. Soon many others were manufactured and improvements were not long in coming. Indeed, two English scientists built a battery composed of silver half-crown coins that were alternated with zinc discs—even before Volta's entire letter had reached England (Reference 18, pg 89); the letter had been sent in two parts with the second part being received several months after the first (Reference 18, pg 66). The technical paper on the voltaic battery, written in the French language by Volta, was read before the Royal Society on June 26, 1800 and the article appeared in print in the same year¹.

Sir Humphry Davy
Humphry Davy (1778-1852), shown to the left¹², immediately recognized the importance of the development of the voltaic battery (or pile or cell) and set out to use the power source for chemical investigations. Quite as an aside from his extensive chemical investigations, Davy was the first person to establish an arc discharge in the laboratory with the use of an enormous voltaic battery. In the following, Davy, in 1812⁴, mentioned the battery he used as well as his observations and descriptions of the discharge:

"The most powerful combination that exists in which number of alternations is combined with extent of surface, is that constructed by the subscriptions of a few zealous cultivators and patrons of science, in the laboratory of the Royal Institution. It consists of two hundred instruments, connected together in regular order, each composed of ten double plates arranged in cells of porcelain, and containing in each plate thirty-two square inches; so that the whole number of double plates is 2000, and the whole surface 128000 square inches. This battery, when the cells were filled with 60 parts of water mixed with one part of nitric acid, and one part of sulphuric acid, afforded a series of brilliant and impressive effects. When pieces of charcoal about an inch long and one-sixth of an inch in diameter, were brought near each other (within the thirtieth or fortieth part of an inch,) a bright spark was produced, and more than half the volume of the 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 at least to four inches, producing a most brilliant ascending arch of light, broad and conical in form in the middle. When any substance was introduced into this arch, it instantly became ignited; platina melted as readily in it as wax in the flame of a common candle; quartz, the sapphire, magnesia, lime, all entered into fusion; fragments of diamond, and points of charcoal and plumbago, rapidly disappeared, and seemed to evaporate in it, even when the connection was made in a receiver exhausted by the air pump; but there was no evidence of their having previously undergone fusion.

"When the communication between the points positively and negatively electrified was made in air, rarified in the receiver of the air pump, the distance at which the discharge took place increased as the exhaustion was made, and when the atmosphere in the vessel supported only one-fourth of an inch of mercury in the barometrical gage, the sparks passed through a space of nearly half an inch; and by withdrawing the points from each other, the discharge was made six or seven inches, producing a most beautiful coruscation of purple light, the charcoal became intensely ignited, and some platina wire attached to it, fused with brilliant scintillations, and fell in large globules upon the plate of the pump. All the phenomena of chemical decomposition were produced with intense rapidity by this combination..."

John George Children
A friend of Davy's was John George Children (1777-1852)¹⁴. When the news of Volta's development reached England, J. G. Children and his father, George Children (1742-1818)¹³, decided to build a large battery for their own investigations. John George Children eventually published two papers^{2, 5} that detailed the batteries built as well as the results of investigations on the application of the batteries to different metal wires. Although Volta and Davy had observed glowing wires with their batteries, the more powerful ones made by Children carried the investigations a step higher. The results of heated wires obtained from their first battery apparently preceded the arc discharge observations mentioned by Davy above.

Michael Faraday
Michael Faraday (1791-1867) was an early associate of Humphry Davy, being his assistant at the Royal Institution in 1813, at age 22. Faraday's portrait, shown to the left, was scanned from the 1868 book by John Tyndall¹⁰. Faraday's contributions to the knowledge of science were extraordinary. His list of discoveries includes electrical induction, which led to the development of magneto-electric machines. He was instrumental in achieving the installation of the first electric light in a lighthouse at South Foreland, near Dover, on the English Channel.

In a lecture delivered on March 9, 1860, before the Royal Institution, Faraday⁸ displayed a lamp (shown below and to the left) that embodied the features of the arc discharge device Humphry Davy had demonstrated about 50 years earlier. In this lamp Faraday utilized two carbon electrodes and the power source was a battery. He exhausted the air so that the carbon would not burn up; this was done to help explain the phenomena taking place in the lamp circuit. The lecture display was used, in part, to show the brilliant light that Davy had achieved with the voltaic battery.

In 1860, Faraday reported⁹ that the electric light (meaning an arc lamp) in the South Foreland lighthouse had been operating for six months without failure. He said:

"By means of a magnet, and of motion, we can get the same kind of electricity as I have here from the battery; and under the authority of the Trinity House, Professor Holmes has been occupied in introducing the magneto-electric light in the light-house at the South Foreland; for the voltaic battery has been tried under every conceivable circumstance, and I take the liberty of saying it has hitherto proved a decided failure. Here, however, is an instrument wrought only by mechanical motion. The moment we give motion to this soft iron in front of the magnet, we get a spark. It is true, in this apparatus it is very small, but it is sufficient for you to judge of its character, It is the magneto-electric light, and an instrument has been constructed, as there shown (fig. 59), which represents a number of magnets placed radially upon a wheel—three wheels of magnets and two sets of helices. When the machine, which is worked by a two-horse power engine, is properly set in motion, and the different currents are all brought together, and thrown by Professor Holmes up into the lantern, we have a light equal to the one we have been using this evening. For the last six months the South Foreland has been shining by means of this electric light—beyond all comparison better than its former light...."

"Trinity House was the first lighthouse authority to employ electric light and it took no less a person than Faraday to overcome the Brethren's reluctance to be first in the field. The lighthouse selected was the South Foreland light and a magneto and arc lamp were installed there in 1859. In order to compare the qualities of the electric arc with the then conventional oil-lamp the two methods of lighting were exhibited simultaneously so that passing ships could report on the comparative qualities of each. It was said that on a clear night the electric arc could be seen for twenty-seven miles, which would be quite possible from a masthead if its height, combined with that of the tower, was 300 feet."

Sir William Robert Grove
The years between about 1810 and 1840 were witness to many investigations carried out on attempts to produce a practical light source with the voltaic arc. One of the reasons for these investigations dealt with the mine explosions that occurred in the collieries in northern England. Many miners lost their lives because of the danger of methane gas coming in contact with the flame light sources of the day. In the year 1815 this problem was presented to Sir Humphry Davy and it was one that he pursued with tremendous success. He developed what was then known as the Davy Safety Lamp. By proper construction of the lantern nearly all potential explosion situations were eliminated. As many as 1500 to 2000 of such lamps were used at one mine location; this was so because of the fact that the light output of such a lamp, being a flame source, was quite feeble. Attempts were made by different investigators to develop an arc discharge source that could be used for that purpose. William Robert Grove (1811-1896) was one of those persons who worked in that subject area. However, Grove decided that an incandescent source might well fill the requirements of illumination.

In one of Grove's articles he said⁷:

"...Not being able satisfactorily to overcome these difficulties, I abandoned it for the time, and made some experiments on another method of voltaic illumination, which appeared to me more applicable to lighting mines; their publication was postponed, and I had nearly forgotten them, until the papers above-mentioned.

"I substituted the voltaic ignition of a platina wire for the disruptive discharge. Any one who has seen the common lecture-table experiment of igniting a platina wire by the voltaic current nearly to the point of fusion, will have no doubt of the brilliancy of the light emitted; although inferior to that of the voltaic arc, yet it is too intense for the naked eye to support, and amply sufficient for the miner to work by. My plan was then to ignite a coil of platinum wire as near to the point of fusion as was practicable, in a closed vessel of atmospheric air, or other gas, and the following was one of the apparatus which I used for this purpose, and by the light of which I experimented and read for hours:—A coil of platinum wire is attached to two copper wires, the lower parts of which, or those most distant from the platinum, are well-varnished ; these are fixed erect in a glass of distilled water, and another cylindrical glass closed at the upper end is inverted over them, so that its open mouth rests on the bottom of the former glass; the projecting ends of the copper wires are connected with a voltaic battery (two or three pairs of the nitric acid combination), and the ignited wire now gives a steady light, which continues without any alteration or inconvenience as long as the battery continues constant, the length of time being of course dependent upon the quantity of the electrolyte in the battery cells. Instead of making the wires pass through water, they may be fixed to metallic caps well-luted to the necks of a glass globe.

"The spirals of the helix should be as nearly approximated as possible, as each aids by its heat that of its neighbor, or rather diminishes the cooling effect of the gaseous atmosphere; the wire should not be too fine, as it would not then become fully ignited; nor too large, as it would not offer sufficient resistance, and would consume too rapidly the battery constituents; for the same reason, i. e. increased resistance, it should be as long as the battery is capable of igniting to a full incandescence.

"The helix form offers the advantages, that the cooling effect being lessened, a much longer wire can be ignited by the same battery; by this increased length of wire, the battery fuel is economised, while a greater light is afforded; by the increased heat, the resistance is still further increased, and the consumption still further diminished, so that, contrary to the usual result, the increment of consumption decreases with the exaltation of effect produced. The very necessity of inclosing the coil in a glass recipient also augments the heat, the light, and the resistance; if I remember rightly, Mr. Faraday first proposed inclosing wire in a tube for the purpose of being able to ignite a longer portion of it...."

It is of interest to point out some aspects of Grove's statements that shed some light on another lamp that has been reported to exist in the chain of developments since the work of Volta. The lamp in question is the so-called De la Rue or De la Rive lamp. Although a more complete discussion of this lamp is given in the write-up labelled "A Lamp of Uncertain Origin", a few words are in order here. As it regards the lamp, it has been described as consisting of a coil of platinum wire within a glass enclosure with electrical contacts leading to brass caps and it was purported to have a vacuum within the glass vessel. Two different years have been given as the date of introduction—these being 1809 and 1820. Writers have credited this lamp development to either Warren De la Rue or Auguste De la Rive.

The 1840 lamp, as described by Grove, fits the description of the lamp in question except for the vacuum within the lamp. However, it should be realized that a platinum filament, unlike a carbon filament, can operate in an atmosphere with some oxygen content without failure. Also, it should be pointed out that Grove mentioned that Michael Faraday apparently was the first to suggest the desirability of inserting the platinum wire within the glass enclosure (see above). Faraday might have made the suggestion in conversation or discussion. Meyer²² made the following statement on his page 60:

"For a number of years he (Michael Faraday) was a consultant to Trinity House on lighthouses, and in 1847 he proposed lighting buoys with incandescent lamps using platinum spiral filaments."

"He reported, in 1847, on the ventilation of the South Foreland lights, and on a proposal to light buoys by platinum wire ignited by electricity."

References
(1) "On the Electricity Excited by the Mere Contact of Conducting Substances of Different Kinds", In a letter from Alessandro Volta to Sir Joseph Banks, Philosophical Transactions of the Royal Society of London, Vol 90, 1800, pp 403-431. Read June 26, 1800.
(2) "An Account of Some Experiments, Performed with a View to Ascertain the Most Advantageous Method of Constructing a Voltaic Apparatus, for the Purpose of Chemical Research", J. G. Children, Philosophical Transactions of the Royal Society of London, Vol 99, 1809, pp 32-38. Read November 24, 1808.
(3) The Bakerian Lecture for 1809. "On Some New Electrochemical Researches, on Various Objects, Particularly the Metallic Bodies, from the Alkalies, and Earths, and on Some Combinations of Hydrogene", Humphry Davy, Philosophical Transactions of the Royal Society of London, Vol 100, 1810, pp 16-74. Read on November 16, 1809. In the caption for Fig. 6, on page 74, Davy mentioned that the large battery being constructed at the Royal Institution had not been completed as of the date of the reading of the paper.
(4) Elements of Chemical Philosophy, Sir Humphry Davy, Printed for J. Johnson and Co., St. Paul's Church-Yard, London, 1812, pp 152-153.
(5) "An Account of Some Experiments with a Large Voltaic Battery", J. G. Children, Philosophical Transactions of the Royal Society of London, Vol 105, 1815, pp 363-374.
(6) The Collected Works of Sir Humphry Davy, Vol. IV (edited by John Davy), Smith, Elder and Co. Cornhill, London, 1840, pp 110-112.
(7) "On the Application of Voltaic Ignition to Lighting Mines", W. R. Grove, The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science, Vol XXVII, 1845, pp 442-446.
(8) Lecture VI - "The Correlation of the Physical Forces", A Course of Six Lectures on the Various Forces of Matter, and Their Relations to Each Other, Michael Faraday, Harper Brothers, New York, 1860, pp 155-156. Delivered before the Royal Institution on March 9, 1860.
(9) Lecture on "Light-House Illumination—The Electric Light". This is the seventh "chapter" in the following book: A Course of Six Lectures on the Various Forces of Matter, and Their Relations to Each Other, Michael Faraday, Harper & Brothers, Publishers, Franklin Square, New York, 1860, pp 171-190. Delivered before the Royal Institution on March 9, 1860. The main six chapters in the book were lectures "Delivered before a Juvenile Auditory at the Royal Institution of Great Britain during the Christmas Holidays of 1859-60". Edited by William Crookes.
(10) Faraday as a Discoverer, John Tyndall, Longmans, Green, and Co., London, 1868.
(11) The Life and Letters of Faraday [computer file], Vol II, Dr. Bence Jones, J. B. Lippincott, Philadelphia, 1870, pg 230. http://www.hti.umich.edu/cgi/t/text/text-idx?c=moa;idno=AJN6604. Click on the second entry and then page 230.
(12) Les Nouvelles Conquêtes de la Science, Vol 1, Louis Figuier, Paris, 1883.
(13) "George Children", Dictionary of National Biography, Vol IV, The Macmillan Co., New York, 1908, pg 249.
(14) "John George Children", Dictionary of National Biography, Vol IV, The Macmillan Co., New York, 1908, pg 249.
(15) "Sir Humphry Davy", Dictionary of National Biography, Vol V, The Macmillan Co., New York, 1908, pg 637.
(16) "William H. Pepys", Dictionary of National Biography, Vol XV, The Macmillan Co., New York, 1909, pg 811.
(17)) Oersted - and the Discovery of Electromagnetism, Bern Dibner, Blaisdell Publishing Co., New York, 1962.
(18) Alessandro Volta and the Electric Battery, Bern Dibner, Franklin Watts, Inc., New York, 1964.
(19) Sir Humphry Davy's Published Works, June Z. Fullmer, Harvard University Press, Cambridge , Massachusetts, 1969.
(20) The Selected Correspondence of Michael Faraday, Vol 1 (1812-1848), edited by L. Pearce Williams, Cambridge University Press, London, 1971.
(21) A History of Lighthouses, Patrick Beaver, Peter Davies Ltd., London, 1971, pg 68.
(22) A History of Electricity and Magnetism, Herbert W. Meyer, Burndy Library, Norwalk, Connecticut, 1972.
(23) Humphry Davy, Ronald King, The Royal Institution of Great Britain, London, England, 1978.
(24) Humphry Davy-Science & Power, David Knight, Blackwell Publishers, Oxford, England, 1992.
(25) Young Humphry Davy - The Making of an Experimental Chemist, June Z. Fullmer, American Philosophical Society, Independence Square, Philadelphia, Pennsylvania, 2000.
(26) Michael Faraday, J. H. Gladstone, Harper & Brothers, Publishers, Franklin Square, New York, n. d. (before January 1885).
(27) JSTOR - The Scholarly Journal Archive; http://www.jstor.org/jstor; On this website it was possible to view the early papers published in the Philosophical Transactions of the Royal Society of London. Access was achieved through a local university.

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