As′tral lamp.
A lamp with an annular oil reservoir connecting by two pipes with the wick tube, the latter being on the summit of the pedestal. It is designed to obviate the interception of light by the oil reservoir, which when placed centrally casts a shade upon the table. In the arrangement shown at Fig. 397 the oil is contained in the annular chamber a surrounding the burner b, which is of the Argand kind (see Argand), and the lower part of the chimney, and thence descends to the foot of the wick through the two tubes c c. It will be seen that the downward rays of light from the burner are not at all intercepted in the immediate vicinity of the lamp, except by the two small oil pipes, and that they are not materially interfered with, within a radius beyond which the light would be insufficient for reading or working by; even this is obviated in a considerable degree by the ground-glass globe d surmounting the annulus, which diffuses and equalizes that part of the light which is not cast downward. The chimney c assists combustion, and carries off the volatile products thereof. |
| Astrolabe. |
