TUE DARK-ROOM LAMP.
It is better to carry on the operations of development by artificial light, for the reason that daylight is constantly varying in intensity, thereby making it difficult to secure uniform density in -a series of nega tives. It is a great advantage if the lamp used for lighting is placed outside the dark-room ; this can be done by support ing it on a. shelf or bracket in front of a ruby window. By this means the heat and fumes of the gas or oil are avoided. With an oil lamp there would be some difficulty in regulating the light ; but if gas is used, candles, paraffin, gas, or electricity. Can dle lamps are admirably adapted for tourists, and for dark-rooms where only a small amount of work is to be done. Patterns of these are shown by Figs. 365 to 367. The last can also be used, with a white glass, as a reading lamp for lantern lectures. Hard candles, such as those used for carriage lamps, are best, the ordinary variety being too soft. Special
candles may be obtained for this purpose.
the supply tap could be fixed inside the dark-room. For a fairly large room there is no objection to the employment of any ordinary form of lamp suitable for the pur pose. These can be obtained for use with If an oil lamp is used, it should have an arrangement for adjusting the height of the wick from the outside ; otherwise, if it burns down while a plate is being de veloped, there is no opportunity of turning it up without opening the lamp and so fogging the plate. Two good patterns are shown by Figs. 36S and 369, while Fig. 370 has the merit of being suitable for either oil or gas. Whatever kind may be chosen, the lamp should be provided with both red and yellow glasses, the latter for use in developing bromide paper. For a very large room, more than one lamp will be required.