This section is from the book "Spons' Mechanics' Own Book: A Manual For Handicraftsmen And Amateurs", by Edward Spon. Also available from Amazon: Spons' Mechanics' Own Book.
The first lamp worthy of notice is that introduced by Argand; it consisted of an annular tube, on which the wick was stretched; of a reservoir containing the oil; of a pipe leading from the reservoir to the wick; and of a holder tor the glass, which imparted, on turning, a spiral motion to the wick and thereby adjusted the flame. The reservoir was of the kind known as the "bird fountain," whereby a bubble of air entering the small orifice at the base allows the egress of a small quantity of oil. This principle has since been applied to a very numerous class of lamps, especially those known as "reading lamps," where the reservoir is higher than the wick. Argand's lamp was suitable for both colza and sperm oils. As the shape was ungainly, many expedients were devised whereby the flame could be fed from a reservoir below. Careel, in 1798, brought out a lamp which was almost universally used for many years in France. The principle of this was pumping, by 2 little clockwork pumps, a supply of combustible to the wick. The only objection to this is the constant need of repair to which the delicate mechanism is liable. The supply, when in good order, however, was so extremely steady as to cause this lamp to be taken on the Continent as a standard of illumination.
The problem of securing an unvarying supply of oil without such complicated mechanism was one which taxed the ingenuity of many makers. A very favourite means was that of hydrostatic power, whereby a heavier liquid solution was made to raise the lighter oil equably, as it consumed.
Keir, in 1787, made a very ingenious lamp, consisting of 2 cylinders, the smaller floating in the larger. The wick was attached to the apex of the interior cylinder which contained the oil, and was open at the base, the exterior being filled with salt water. As the oil diminished, the salt water rose in the interior, and sank in the exterior reservoir, while the height of the interior cylinder was adjusted by means of a wooden float. Porter, in 1804, invented a lamp which deserves mention, and which consisted of a rectangular box, balanced eccentrically, so that the position - horizontal at the commencement - during burning, gradually approached the vertical. A larger amount of oil being removed from the posterior, caused this to lose weight more rapidly than the anterior, the oil in which was thereby maintained at a level. The name of Smethurst is closely associated with lamps. He was the first to give a slope to the chimney, which Argand had left straight, thus directing the air-current more accurately, and thereby increasing the draught and the brilliancy of the flame. The next invention of importance took place in 1836, when Fanchot invented the moderator lamp as at present used.
This had already been foreshadowed in the inventions of Stokes (1787), Allcock (1807), and Fayre (1825), all of whom used pistons which forced the oil up under pressure. Fanchot gave the lamp its present form, which is, briefly, as follows: - The piston fits tightly in the reservoir, being provided with a leather collar, which admits of being raised with ease while the reservoir is full, but the descent is impeded by the collar being pressed against the sides by the liquid. There is, therefore, no outlet for the oil but by a fine tube passing through the piston up to the wick, which is, by this means, fed by a constant stream of oil, the surplus dropping down into the reservoir above the piston. When the piston has fully descended, it is re-elevated by a cog and ratchet apparatus. The flow of liquid up the tube is regulated by a fine piece of wire, which partly closes the same and helps to cleanse it. By these means, very heavy oils can be burnt, and perhaps no lamp has enjoyed greater popularity than this. Its defects are the constant need of winding up, and liability of the fine tube to become clogged. Young's "Vesta " lamp, first used in 1834, burnt "camphine," or turpentine, with a very brilliant snow-white flame.
The "Diacon" lamp was a modification of the moderator, invented and used in America.
The wick has been the subject of numerous modifications. As early as 1773, we find one Leger producing a flat-ribbon wick. Though a great improvement on that of the older cord wick, the flame was too thin, being blown out with every puff of air. Argand introduced the circular wick, which has maintained its form. A great step was made when the flat wick was forced, as in modern lamps, to adjust itself exactly to an annular tube, thus obviating the necessity of pushing the tube into an ill-fitting wick. In 1865, Hincks, of Birmingham, brought out a lamp with two parallel flat flames, called the Duplex, which gives a remarkably good light, and has a world-wide reputation. To the same firm are due ingenious devices for extinguishing and re-lighting the flame without moving the shade, by merely pressing a trigger.
An entirely different variety is Holliday's vapour burner lamp, of which many thousands are to be seen burning on costermongers' stalls in East and South London. The conical reservoir at the top is filled with light hydrocarbon oil, passing through a tap and tube into a burner of peculiar construction, and being ignited by holding in a flame for a few seconds, will continue to burn without wick furiously and safely as long as the supply is properly regulated. This may be said to be the first lamp which burnt hydrocarbon oils, and no doubt for an open-air flame no better can be, or at any rate has been, devised. Invention has been very active to devise means of burning hydrocarbon oils with safety in household lamps. In 1866, Leichenstadt invented a lamp for burning a mixture of benzole and camphor, but the dangerous nature of benzole rendered this form undesirable. Aaronson, in 1875, by a clever combination of oil and water, constructed a lamp to be extinguished directly it was overturned, or even deflected from the vertical. This masterpiece could also be trimmed, filled, and lighted without moving the shade and chimney. Young and Silber are 2 names most prominent in the lamp problem.
James Young, as the discoverer and first manufacturer of paraffin oil from shale, was naturally the appropriate inventor of means for its safe combustion, and Young's Company now still supply "Vesta" lamps for burning their own productions.
All the inventions thus briefly epitomized, have one or other of the following objects in view: - To supply oil regularly to the wick; to apportion the supply of air to the description and quantity of oil to be burnt; to provide simple means for regulating the height of the wick, and consequently, the flame; and finally, to place the burning portion of the lamp in such a position as not to be obscured by the reservoir and other portions. The oldest lamps, as the antique Etruscan, and the cruisie of Scotland, were on the suction principle, and the wick depended for its supply upon its own capillary action. As the level of the oil was constantly varying, so the light varied also, and the first attempts of inventors were directed to maintaining an equal level of oil. The bird-fountain and hydrostatic reservoirs partly attained this end, and the Carcel and Moderator systems were perfect of their class, mechanical or pressure lamps. It is evident that suction lamps depend for their efficacy upon the gravity of the combustible. A spirit lamp, with a good wick, will burn very well, though the wick be several inches above the liquid.
With liquids volatilizing at low temperatures, there is always a danger of the formation of explosive mixtures.
In 1834, Beale patented a lamp for burning mineral and wood naphthas, and oils from the distillation of coal tar, vegetable tar, and the like; the principle being the vaporization by means of a small secondary flame, from a separate source, which soon burns out, having started the vaporization. This lamp had no wick; the supply of fluid was regulated by forced air.
Parker's lamp, patented 1840, should also be mentioned, as the most successful attempt at heating the oil before combustion. Here the upper part of the chimney was made of copper, and passed through the reservoir filled with a heavy luminant (preferably coconut oil or tallow). The air being expended, the oil fed the wick by its own expansion, regulated by an ingenious mechanism. This was a so-called "sinumbral" lamp, and appears to have been held, by some, superior even to Carcel's as a standard for photometry.
The supply of oil to the wick in all pressure lamps was in excess of the demand, and the surplus fell back into the reservoir. This can only be feasible in the case of heavy-oils, especially animal and vegetable. The Russians boast of having constructed a lamp to solve the problem of burning their own heavy hydrocarbon oils, of which Baku produces so vast a quantity; but as the demerits of such oils, especially the clogging of the wick, cannot be ascertained in the few hours their committee appear to have spent upon the investigation, we must defer our meed of applause. The light hydrocarbons, such as petroleum, photogen, solar oil, and their polynomial varieties, must reach the arena of combustion in as small quantities, and at as high a temperature as possible, while the supply of air, both from inside and out, can scarcely be too abundant.
At first sight, the burner of the Silber lamp appears to be a simple aggregation of concentric tubes - and this, in fact, it is. The use of these, especially of the innermost, bell-mouthed pipes, becomes very apparent in the lighted lamp. Remove the interior tube, and immediately the flame lengthens and darkens, wavers and smokes. The current of air which is, by this internal conduit, directed into the interior flame surface, is the essential principle of Silber's invention. The wick is contained in a metal case, surrounded by an air-jacket, which passes down the entire length of the lamp, leaving a small aperture at the base, through which the oil flows from the outer reservoir to the wick chamber. Thus, by the interposition of an atmospheric medium, the bulk of the oil is maintained throughout at a low temperature; 2 concentric bell-mouthed tubes pass down the interior of the wick case, and communicate with the air at the base of the lamp, which is perforated for the purpose; 2 cones, perforated, the inner and smaller throughout, the largest only at the base, surround the wick, and heat the air in its passage through the holes to the flame.
The effect of these appliances is, firstly, by the insulation of the outer reservoir, to avoid all danger of vaporization of the oil, till actually in contact with the wick. As it is drawn nearer and nearer the seat of combustion, the hot metal wick-holder heats, and ultimately vaporizes the luminant, so that at the opening of the wick tube concentrically with the air conduits - all of which are exceedingly hot - a perfect mixture of vapour and hot air is formed, and burned. An all-important feature is the shape and position of the chimney, which influences the flame to the extent of quadrupling its brilliancy if properly adjusted.
The preceding remarks have been condensed from Field's Cantor Lecture on Illuminating Agents, read before the Society of Arts.