The gauze cylinder should be fastened to the lamp by a screw b, [fig. 615.], of four or five turns, and fitted to the screw by a tight ring. All joinings in the lamp should be made with hard solder; as the security depends upon the circumstance, that no aperture exists in the apparatus, larger than in the wire-gauze.
The parts of the lamp are,
1. The brass cistern a, d, [fig. 615.], which contains the oil. It is pierced at one side of the centre with a vertical narrow tube, nearly filled with a wire which is recurved above, at the level of the burner, to trim the wick, by acting on the lower end of the wire e with the fingers. It is called the safety-trimmer.
2. The rim b is the screw neck for fixing on the gauze cylinder, in which the wire-gauze cover is fixed, and which is fastened to the cistern by a screw fitted to b.
3. An aperture c for supplying oil. It is fitted with a screw or a cork, and communicates with the bottom of the cistern by a tube at f. A central aperture for the wick.
4. The wire-gauze cylinder, [fig. 614.], which should not have less than 625 apertures to the square inch.
5. The second top, 3⁄4 of an inch above the first, surmounted by a brass or copper plate, to which the ring of suspension may be fixed. It is covered with a wire cap in the [figure].
6. Four or six thick vertical wires, g′ g′ g′ g′, joining the cistern below with the top plate, and serving as protecting pillars round the cage. g is a screw-pin to fix the cover, so that it shall not become loosened by accident or carelessness. The oil-cistern [fig. 615.] is drawn upon a larger scale than [fig. 614.], to show its minuter parts.