144 Miscellaneous Intelligence. 



3 inches high, contains tlie oil ; in its centre is aflixed a strong 

 iron rod, upon which the upper part of the lamp, hereafter to 

 be described, moves. 



Another cylindrical vessel, open at top, 3^| diameter, and 7 

 inches high, surrounds the oil vessel, leaving a space of ^*^ of an 

 inch between the two vessels. These vessels are then united at 

 bottom, and made air-tight, and the -f^ space filled with mercury. 



Another cylindrical vessel (called the plunging cylinder, be- 

 cause it plunges into the mercury in the -f^ space), closed at 

 top, and open at bottom (3^% diameter, and 3 inches high), is 

 firmly aittached to the connecting tube and burner of the lamp, 

 the tube ascending to the required height of the light, and de- 

 scending to the lower level of this plunging vessel. This tube 

 moves up and down the centre iron rod on points, or pins, to 

 prevent friction or capillary attraction. 



The oil-vessel being filled with oil, and the -f^ space with 

 mercury, it is evident the plunging vessel, and oil-tube attached 

 thereto, entering the mercury and oil at the same time, in the 

 manner of a gasometer, the air contained in the plunging vessel 

 cannot escape, and the whole weight of the plunging vessel 

 (which is loaded to raise the oil the required height,) presses 

 upon the oil, through the elastic medium of air, and forces the 

 oil up the centre tube to the adjusted height. This action 

 continues until all the oil is consumed. 



The advantages of this lamp are, that it burns till all the oil 

 is consumed. 



That the oil and weight being in the base, it is not liable to 

 be overthrown, nor can any oil be spilt. 



That it is as perfectly shadowless as a gas-light, and capable 

 of as much beauty of form. 



That there being neither valve, spring, nor screw, it is not 

 liable to be out of repair, and is easily managed by servants, 

 the oil being poured into an open vessel, instead of a small 

 aperture. The mercury is never removed. 



That being made of iron, it is not the least acted upon by oil. 

 It may also be mentioned, that the oil tubes clean themselves 

 every time the lamp is charged with oil. 



That, independent of less first cost than other lamps of equal 

 appearance, it is economical in other respects. No light is 

 wasted, as in the French, or even the Sinumbra lamps, for 

 though in the latter the shadow projected from the ring reser- 

 voir is overcome, it is only by calling in aid the rays of light 



