358 



I, AM I 1 . 



vessel, acting on the principle of the bird fountain, 

 having a neck at the bottom, and being closed at 

 the top by a lid, which is lifted when the vessel is 

 to be supplied with oil, the neck being at that time 

 held uppermost. The oil is poured in by the small 

 opening t, which is uncovered by sliding the tube Q, 

 and when filled, the tube is restored to its former 

 position, and the vessel A placed in its seat F. 

 When by the consumption of the oil the surface in 

 F is lower than the opening, then a bubble of air 

 ascends into A, and the oil falls, until the opening 

 t is covered by the oil in F ; as by reason of the 

 heating of the air within the vessel A, more oil will 

 come down than is necessary for the supply of the 

 wick, which surplus oil is allowed to fall down to 

 the cup P, through the tube g, which cup is screwed 

 to the bottom ol the tube d. The burner or cylin- 

 drical part, containing the cylindrical wick, consists 

 of three concentric tubes, d, f, g. The tube g is 

 fixed by solder to the bottom of the tube rf, and the 

 space between them is occupied by the cylindrical 

 cotton wick steeped in oil. The oil flows from the 

 large vessel through N, and enters the cavity 

 between the exterior surface of the tube g, and 

 the interior surface of the tube d, rising to the 

 level of the opening t. There is a short tube, i, 

 which receives the wick, aiul is made so as to slide 

 easily up and down on the tube g. The wick 

 tube lias a projecting pin inwards, which fits into 

 a spiral groove cut in the tube AT, so that when the 

 wick tube is turned round, the pin moving in the 

 spiral groove, causes the wick tube to rise or 

 fall, and consequently the wick itself. The wick 

 tube is connected with the outer tube/, by means of 

 a catch, so that by turning this latter tube, the height 

 of the wick can be regulated at pleasure. On the 

 outside of the tube d, a ring, r n, is fixed, which 

 supports the glass chimney R G. There is a wire * 

 attached to the tube /, and bent over the edge of 

 the tube d, and r n is connected with four wires 

 which attach it to a ring q, surrounding the tube d, 

 by turning which ring, therefore, the wick is raised 

 or depressed. The air which supports the combus- 

 tion on the outside of the flame, enters through the 

 holes m m, in the ring r n, and the combustion in the 

 interior part of the flame, is supported by the air 

 which enters the holes o o, and passes up through the 

 tube g. The subjoined wood cut, fig. 2, represents 

 the exterior form of an argand lamp, with count 

 Rumford's circular ring oil vessel, in which lamp, 

 there is besides the small chimney, a large hemisphe- 

 rical vessel, ground rough on the inner surface, and 

 resting on the oil ring 



Fig. 2. 



Fig. 3. 



Sir Humphry Davy invented a safety lamp for gw 

 ing light in mines where fire-damp prevails. He found 

 that a lamp constructed with an envelope of wire 

 gauze, the apertures of which occupy greater space 

 than the solid wire, would not cause explosion in fire- 

 damp. The wire gauze should not contain fewer 

 than 784 apertures in the square inch, and the wire 

 should be either iron or copper, but by no means 

 brass. Fig. 3, exhibits a view of the safety lamp, 

 as commonly constructed. A is the oil cistern, B is 

 a brass rim firmly attached to the wire gauze cylin- 

 der F; C is the feeder, through which oil is poured 

 into the lamp ; E is a wire which passes through a 

 safe tube in order to trim the wick ; G is a brass 

 cap on the top of the cylinder of gauze, the cap being 

 about 3-4ths of an inch above the gauze cover of the 

 cylinder ; 1 1 are strong wires to strengthen the lamp, 

 and K is a ring to hang the lamp by. 



Fig. 4, represents a self generating gas lamp. A 

 is a hollow ring for containing oil on Count Rum- 

 ford's principle. The oil passes from this fountaii 



Fig. 4. 



down the tubes B B, and enters the upright tube C, 

 to a height equal to the height of the ring. At this 

 part of the upright tube there is a shallow cup sur- 

 rounding it. At a distance of rather more than an 

 inch above this, there is a thin brass cap fitted on to 

 the top of the tube C, the cap being narrow at the 

 bottom, and ground so as to fit accurately on the 

 tube ; above this sort of ring, at the bottom of the 

 cap, it widens into a bulb, perforated witli ten or 

 twelve small holes, as jets, and the upper part is 

 a straight tube closed at the top. There is a tube 

 D at the bottom, which, by being turned round, acts 

 in a screw, and raises or depresses the oil in the tube 

 C, so that it stands at the proper level. Now, a small 

 quantity of alcohol or common spirits being put into 

 the cup, on a level with the ring, and set fire to, 

 will heat the tube C to such a degree, that the oil 

 within it will boil, and gas will be evolved. This 

 gas rises into the cap on the top of the tube, and 

 having no other way of escape, issues out of the holes 

 in the side of the cap, and the alcohol continuing 

 still to burn, sets fire to the jets, and a series ol 

 beautiful clear lights is the result. The heat of the 

 gas lights themselves, is sufficient to keep the oil 

 boiling, so that the flame acts not only as a light, 

 but as a self generator. A considerable quantity of 

 carbon is deposited on the outside of the tube, 

 which may be prevented by slipping on several thin 

 washers, which being stripped oft" when the lamp 

 is trimmed, the former deposition of carbon will bo 

 removed 



