Even with the proper current, lamps soon begin to deteriorate, as small particles of carbon leave the filament and cling to the glass. This is due to the evaporation, and it makes the filament smaller, and a higher pressure is then needed to force the current through the increased resistance; besides this, the darkened bulb does not properly let the light out. The current may be direct or alternating.
Fig. 201.
Fig. 202.
151. The Uses to which incandescent lamps are put are almost numberless. Fig. 193 shows a decorative lamp. Fancy lamps are made in all colors. Fig. 194 shows a conic candle lamp, to imitate a candle. What corresponds to the body of the candle (see figure B to C) is a delicately tinted opal glass tube surmounted (see figure A to B) by a finely proportioned conic lamp with frosted globe. C to D in the figure represents the regular base, and thus the relative proportions of the parts are shown. Fig. 195 shows another form of candelabra lamp. Fig. 196 shows small dental lamps. Fig. 197 shows a small lamp with mirror for use in the throat. Fig. 198 shows lamp with half shade attached, used for library tables. Fig. 199 shows an electric pendant for several lamps, with shade. Fig. 200 shows a lamp guard. Fig. 201 shows a lamp socket, into which the lamp is screwed. Fig. 202 shows incandescent bulbs joined in parallel to the + and - mains. Fig. 203 shows how the lamp cord can be adjusted to desired length. Fig. 204 shows a lamp with reflector placed on a desk. Fig. 205 shows a form of shade and reflector.
| Fig. 203 | Fig. 204. |
Fig. 205.