PETROLEUM LAMPS. i39 
oval chimneys, either of glass or mica, have been made to correspond 
with the flat flame. 
4. The liability of glass chimneys to break from unequal heat, or 
accident, as well as their expense and inconvenience, have made it a 
desideratum to construct a good hand-lamp without a chimney, for which 
purpose many patents have been granted, of very various forms, with 
more or less success. Some have used numerous very small wicks, 
others verj r thin wicks ; others have made, in effect invented, metallic 
chimneys below the flame. To keep the oil in the lamp as cool as pos- 
sible, so as not to throw off more gas than the flame can consume, 
various non-conductors have been interposed between the burner and 
the reservoir, such as porcelain, glass, gypsum, wood, gutta percha, &c. 
Other inventors have effected the same object by isolating, in a great 
measure, the burner, by resting it on slight metallic points, &c. In a 
few examples oxygen has been ingeniously and effectively, but rather 
expensively, supplied to the flame by a revolving fan-wheel propelled 
by machinery enclosed within the base of the lamp. 
5. Other improvements have been introduced, removing the chimney 
vertically, horizontally, or obliquely, so as conveniently to turn and 
light the lamp or supply it with oil; others effecting the same objects 
without removing the chimney at all. Mica and glass deflectors have 
been used instead of metallic ones, and glass cylinders surrounding 
the flame and below it, so as to avoid the shadow around the base of 
the lamp. 
6. The necessities and demands of the great American railway 
system have originated improvements in locomotive head-lights, so as to 
obviate the effect of the motion of the engine and counteract strong 
currents of wind ; also in lanterns, so as to avoid extinguishment by 
sudden motions, vertically or laterally, and so that the lamp may be 
easily fastened in or removed from the case and the wick regulated 
without removal therefrom. 
7. Finally, great improvement has been made in the machinery for 
the manufacture of every part of the lamp, so that for a few cents a 
good and convenient and even elegant lamp for burning this cheap and 
highly valuable native oil is now within the reach of every family in 
the land. 
