DESCRIPTION OF A LAMP. I 13 



the pivots : e, large wheel, the pinion of which is driven by Particular de- 

 the wheel of the barrel: ////, ends of the pillars : A, the fly JgJSJgJJ 

 and its endlefs fcrew, the lamp. 



Fig. 2. Plan of the upper fide of the movement : i, upper 

 brafs plate: k, the bottom of the refervoir of tin: / I /, con- 

 necting pillars : m m, a circle with its fcrews, which ferves to 

 fupport the pump and its apparatus : n, body of the double 

 force pump : o, aperture through which the oil rifes through 

 the afcending pipe : The elevation of this pipe is feen at o, fig. 

 3 : p, the double arm of the piftons of the pump : q q, pump 

 rods. 



Fig. 3. Lateral elevation of the mechanifm: ssj the plate 

 which covers the body of the lamp, fixed by four fcrews, which 



^at the fame time connect the lower plate u : This plate is raifed 

 up in the drawing inftead of being fere Wed down, in order to 

 give a clearer idea of the connection. The middle piece t is 

 perforated by two cylindrical holes, in which the piftons move 

 which drive the oil. The piece t is alfo perforated above and 

 beneath, in order to admit of two conical valves opening up- 

 wards into each cavity or pump barrel. The lower valve in 

 each fuffers the oil to rife into the barrel as the piilon is with- 

 drawn, and the upper fuffers it to pafs upwards when the 

 forcing ftroke takes place. The pieces s, t, and u, are fecured 

 by a piece of leather put between them before they are fcrew- 

 ed together. 



The dotted line v v denotes part of the refervoir of oil : w, 

 part of the lower plate m : x, one of the pillars : y, the barrel 

 containing the fpring : z, pinion of the large wheel : A, pinion 

 of the wheel of the endlefs fcrew : B, the wheel which drives a 

 crank that works the pumps : C, the leading piece which acls 

 on the lever : D, pinion of the wheel B. E, middle wheel, 

 taking in the pinion D, and moved by its own pinion, which 

 takes in the great wheel e : F, lever that works the arms of 

 the pump. 



Fig. 4. Elevation of the natural &ze of the glafs globe r : 

 1 , A pivot of fteel which pafTes through the glafs globe to 

 communicate with the arms of the pump. The lower part of 

 this pivot is fquare, in order to receive the lever of ofcillation; 

 the upper part is round, and has the arms of the pump driven 

 tight upon it. 2, A brafs focket in which the pivot ], 3 turns, 

 and is prevented from defcending by a moulder. The glafs 



Vol. II. — June, 1302. I globe, 



