LAMP. 



Tardan'i 

 lamp, or 

 fountain re- 

 crvoir. 

 PLATE 

 CCCXMI. 

 Pig. 11. 



Lamp. On this account, another form of the lamp is used in 

 """"Y^"' houses. The oil vessel is a small globe, and the wick 

 rises out of a nozzle formed on the upper side of it. 

 The only objection to this is, that the surface of the oil 

 sinks down as it is consumed, and at length the wick 

 has to draw the oil up from such a depth, that it can 

 only yield a diminished supply to the flame. 



The fountain reservoir is a very good method of sup- 

 plying the wick of a lamp with oil : See Plate CCCXLI F. 

 Fig. II. In this, the reservoir A A, which contains the 

 store of oil, has only one opening in it, and that is 

 in a neck B proceeding from the lowest part. The re- 

 servoir must be inverted in order to fill it with oil ; but 

 when it is in use, the opening into the neck is immer- 

 sed beneath the surface of the oil contained in the small 

 cup or dish D. Where the wick C is placed, the oil in 

 the cup D precludes the admission of air, and conse- 

 quently the oil cannot descend out.of the reservoir. But 

 when the oil in the cup D is ,so far diminished, as to 

 allow a bubble of air to enter into the opening of the 

 neck B, it will rise up into the reservoir, and allow an 

 equal quantity of oil to descend into the cup for the 

 supply of the wick. But as this will raise the oil in the 

 cup, so as to cover the opening into the neck, no more oil 

 can come out until that which is in the cup is consumed. 

 By this means, as long as the reservoir contains oil, the 

 oil in the cup must always preserve the same level, but 

 will never run over. E represents the small nozzle, which 

 holds up the wick in a perpendicular direction. It is 

 a short piece of tube, with three projecting feet at the 

 lower part, which stand in the bottom of the cup. 



This fountain reservoir, was known by the name of 

 the lamp of Cardan in the time of Mr. Boyle. That 

 gentleman made one in an improved form, which is 

 described in the early Philosophical Transactions. It 

 consists only in making the cup D, into which the oil de- 

 scends, of a considerable area, and forming a communi- 

 cation between this and another small cup, which re- 

 ceives the wick. By this means, the oil is less liable to 

 descend in gluts. 



Fig. 10. is a simple lamp, which has the property of 

 supplying the wick very regularly with oil. This is 

 called the automaton lamp ; and a Mr. Porter had a pa- 

 tent for it in 180k The wick is situated at f, at one 

 end of a rectangular vessel AA, which contains the oil. 

 The whole lamp is suspended by a wire loop R on cen- 

 tre-pins at k, in the manner of a scale beam, so that the 

 lamp is at liberty to librate freely The position of the 

 centre k is such, that the lamp will incline as the oil 

 contained in it diminishes, as is shewn by the dotted 

 lines ; and the inclination will in all cases be such, that 

 the surface of the oil will just reach to the proper height 

 on the wick. The makers of these lamps have attained 

 this end from experiment with great precision, and the 

 drawing, Fig. 10. is taken from one of them. 

 Argand's The best kind of lamp is that of Argand, which was 

 lamp. invented in France about 1784. The wick is a hollow 

 cylinder or tube ; and the upper part of it when light- 

 ed, forms a ring or short tube of flame. A rapid current 

 of air is made to pass through the insideofthe tube aswell 

 as the outside. To produce this current, a cylindrical 

 glass chimney is placed over the flame, and the rarified 

 air which ascends through the chimney, causes a cur- 

 rent to pass on each side of the flame that is on the 

 outside and inside of the ring of flame. 



Figs. 1, 2. Tnis J ara P is exhibited in Plate CCCXLII. Figs. 1 and 

 2, the former representing the external form, and Fig. 

 2, a section of the part called the burner, which con- 



Porter's au- 

 tomaton 

 lamp 

 Fig. 10. 



tains the wick. A, Fig. 1, is the oil reservoir, from 

 which the oil descends into the oil cistern B, one drop at 

 a time, and is thence conveyed by a pipe C to the burner 



E. The external appearance of the bu*oer is a per- 

 pendicular tube, E; within this is a smaller tube F, 

 (Fig. 2.) which is closely united to the former at the 

 lower end, but both are open at top. The space be- 

 tween the two tubes, therefore, forms a narrow circular 

 cistern, which is freely supplied with oil through the 

 pipe C, but the oil cannot rise above the dotted line e, 

 because the oil reservoir A is constructed in the man- 

 lier of the fountain. The wick G is a circular tube of 

 cotton placed in the space between the two tubes E and 



F, and the top or upper end of the cottgn r.ses a little 

 above the tubes at^/i At that part the flame is pro- 

 duced. H is the glass chimney, which rises up to a con- 

 siderable height, as shewn in Fig. 1. ; the lower part 

 is enlarged, and stands on a -small circular gallery I J. 

 The interior tube F, Fig. 2. is open at the lower end, 

 and the air can freely enter therein as shewn by the 

 arrows ; and this air rising up through the tube F, 

 must pass in contact with the interior of the circular 

 ring of flame. The air for the supply of the external 

 part of the flame enters beneath the gallery 1 1, and rises 

 up within the glass chimney, which is contracted at the 

 place most favourable for projecting the air upon the' 

 flame. This chimney is one of the great improvements 

 introduced by M. Argand. The heated air in the glass 

 chimney, being lighter than the external air, is forced 

 upwards by the cold air which rushes in beneath the 

 edge of the glass chimney, and also up the interior 

 tube as shewn by the arrows. This cold air passing in 

 immediate contact with the flame affords oxygen to 

 it ; and that portion of air which is not consumed 

 becomes heated, and, by ascending the chimney, give? 

 place to a fresh supply of air, so that a constant cur- 

 rent is kept up. 



Another valuable improvement, first introduced by 

 Argand, is the mechanism to elevate or depress the 

 wick at pleasure above the tops of the tubes E, and 

 thereby regulate the height of the flame. In Argand's 

 original lamps, the wick was raised up by a rack and 

 pinion, but the more modern construction is shewn in 

 Fig. 2. The exterior surface, of the tube F, Fig. 2. has 

 a spiral groove or notch formed round it, and the cy- 

 lindrical cotton wick G is stretched tight over a short 

 piece of tube or ring r, which slides up and clown up- 

 on the tube F, a small tooth projects on the inside of 

 the ring r, and enters into the spiral groove. Now it 

 is plain, that if the ring r is turned round, its tooth 

 acting in the spiral groove will cause the tube to ascend 

 and descend, and also the wick which is attached to it. 

 To give motion to the ring r from the outside, a move- 

 able tube is placed within the tube E and F, and in- 

 closes the ring r within it. On one % side of this tube 

 a notch is cut from top to bottom, and a second tooth, 

 which projects from the outside of the ring, enters, into 

 this notch. The tube rises a little above the top of the 

 external tube E of the burner, and has three small wires 

 p fastened to it, which descend to the gallery I I, and 

 are fixed thereto so as support it ; the same wires also 

 fit the interior of the glass chimney, and prevent it 

 from being overthrown. By turning the gallery I I 

 round, the tube attached to it is made to turn round, 

 and the projecting tooth of the ring r communicates 

 motion to the ring also. As before mentioned, the in- 

 terior tooth of the ring, acting in the spiral groove, 

 moves the ring r and the wick up or down ; the 



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xi.fr. 

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