508 



LAMP. 



Lamp. 



Barton's 



hydrostatic 



lamp. 



Cartel's 



mechanical 



lamp. 



PLATE 



CCCXLI1, 



Fig. 5. 



Fig 5. 



fig. 6, 7. 



nltitutle to keep it in equilibrium, viz. from I to D. 

 Hence in this lamp, though the oil does not stand always 

 at the same level, yet the lamp sinks as much as the oil 

 wastes, so that it is always at the same height below 

 the flame. R is a wire fixed perpendicularly to guide 

 and steady the lamp when it rises or falls. 



Mr. Barton's hydrostatic lamp is on the same princi- 

 ple as that of Mr. Edelcrantz, but is more complete, be- 

 cause it is not so liable to be deranged by a small dif- 

 ference of the load. In Mr. Barton's the external ves- 

 sel L is carried upwards to a sufficient height to employ 

 water instead of mercury ; this will be when the water 

 is as high as the dotted line KK, and it is evident that 

 the effect will then be the same as before described. 



Mr. Barton does not employ the Argand burner, but 

 4 burners with wicks the size of that of a candle. 



The lamp which we consider the most perfect for the 

 closet of a student, is the mechanical lamp of Carcel. 

 In this the burner is upon Argand's construction, and 

 the oil is ahvays supplied to it by small double pumps 

 worked by a piece of mechanism in the lower part of 

 the. pedestal. The advantage of this lamp is, that the 



011 can always be supplied in abundance without ever 

 rising too high or sinking too low ; the pumps are adapted 

 to raise more oil than the flame consumes, and the super- 

 fluity runs over the top of the tube containing the wick, 

 and runs down to the pumps again. 



Fig. 5. is a view of this lamp, and a section of the 

 part containing the mechanism for the pumps. AA is 

 the oil vessel ; B the pumps from which the oil is car- 

 ried up by a pipe X to the burner at the top of the pe- 

 destal. The mechanism which gives motion to the 

 pumps is contained in the space beneath the oil vessel 

 A ; the maintaining power is a clock- spring D, which 

 must be wound up every day by a key like a watch. 

 On the lower edge of the barrel is a cog wheel af 108 

 teeth ; this turns a pinion of 12 leaves on the arbor of a 

 second wheel which has 84 teeth, and turns a pinion of 



12 on the arbor of a wheel of 96' ; this turns a pinion of 

 12, on the arbor of which is a small crank to give mo- 

 tion to the pumps B ; on the same arbor is a wheel 

 which turns a worm, and a fly or fan, to regulate the 

 motion. To convey the motion to the pumps B which 

 are in the upper chamber or oil vessel, a small arbor 

 rises perpendicularly up through the bottom of the oil 

 vessel. This arbor has a lever on the lower end which 

 the crank actuates, and on the upper end a double lever 

 with two arms turning down to work the two pump 

 pistons ; the arbor of the lever passes through a tube 

 joined to the bottom of the oil vessel, and a small glass 

 is cemented round the tube to contain a few drops of 

 treacle, which is viscid, and will not suffer the oil to 

 leak down by the arbor into the wheel- work. 



Figs. C and 7 represent the double pump. It has two 

 barrels or chambers, with a piston working in each. 

 The pistons a b are only small pieces of steel wire, and 

 the chambers or barrels are holes drilled horizontally in 

 a thick piece of brass B, the wires are accurately fitted 

 to these holes, and require no packing. The valves of 

 the pumps are shewn in Fig. 7 ; and for the convenience 

 of repairing them, they are situated in the joints be- 

 tween the piece of brass B, which receives the pistons, 

 and two others, plate E and F, one above and the other 

 below ; the ascending pipe C is soldered to the upper 

 piece, and all three are firmly joined together by a screw 

 at each angle. 



These lamps are in great use in Paris ; and we have 

 found them answer their intended purpose better than 

 any of the others which we have tried. 

 Street Lamps. The common lamps for illuminating 



the streets of London, are upon a very imperfect con- Lamp, 

 struction, being only a flatoil dish for burner, sus- V *" P "V^ > ' 

 pended in a glass vase. No provision is made for the en- ?' 

 trance of the fresh air, except through the"same chimney ampS 

 at which the smoke and heated air issue. From the de- 

 fective supply of air, the flame is very weak, and the glass 

 is soon obscured by the smoke. To increase the light, 

 some parishes in London have adopted lamps with 

 lenses, to concentrate the light, and throw it upon par- 

 ticular parts of the foot-path; but as this must abstract 

 the light from other parts of the space which should be 

 illuminated, no advantage whatever is gained by this 

 addition. 



Fig. 8. and Q. represent Lord Cochrane*s patent lamp, Lord Coch- 

 which possesses all the advantages without any of the rane ' 

 defects of the common lamp. The glass vase N, is p"",.^ 

 made of a hemispherical figure, and the light is placed cccx^H 

 in the centre, so that the rays pass through the glass Fi gs . 8, .' 

 perpendicular to its surface. The top of the vase is 

 covered up by a close cover K, from the centre of which 

 a chimney L rises up nearly to the top of the roof or 

 head M, and terminates beneath the openings at the 

 top of the same, where the smoke and heated air issue. 

 To supply the lamp with fresh air, a curved tube f is 

 carried beneath the oil reservoir c, and supplies a con- 

 stant current of fresh air to the flame, which is situated 

 just between the orifices, or mouths, at the extremity 

 of the air pipef, one being on each side of the wick, 

 so that they project the air immediately upon the flame. 

 The heated air, which is contained in the chimney L, 

 cannot balance the cool atmospheric air which enters 

 freely through the air- pipe /; and rushing by the flame, < 



displaces the hot air ; but, becoming heated, it will be 

 forced up the chimney by the fresh air which follows 

 through the air-pipe. By this means a most brilliant 

 flame is kept up. That as little light as possible may be 

 lost, the oil-vessel e is made very narrow, and the light 

 which is thrown upwards to the cover K, is reflected 

 downwards again on the pavement. The head, or roof 

 M. of the lamp, is made with holes all round the lower 

 edge to admit fresh air, and has also an opening in the top 

 to allow the hot air to pass out ; but both the air pipe 

 e, and the chimney L, are open to the chamber or space 

 within the head M, and the consequence is, that the 

 flame is never disturbed by winds, because, by the 

 blowing of the wind, the air in the chamber KL is ren- 

 dered more dense, it will increase the pressure equally 

 upon the orifice of the chimney L, and upon that of the 

 air pipe e, so that the two actions will be balanced. 



For the convenience of trimming and lighting this 

 lamp, the roof M is made to take off, but not the cover 

 K. The chimney L is not fastened to the cover, but 

 to a piece which lays upon it: this piece being lifted 

 up, as shewn in Fig. 9- will rise upon a joint, or hinge, 

 at a, and the oil vessel e being suspended on the same 

 joint, .will be turned up likewise, so that the part con- 

 taining the wick will rise up through a hole' in the 

 centre of the cover into a convenient situation for light- 

 ing the wick or replacing the cotton, as seen in Fig. 9. 

 The oil vessel e is of the fountain kind ; and when it is 

 raised up in this way, the hole, or orifice for the ad- 

 mission of air, will be higher than the vessel, so that 

 the oil can be poured in ; but when the oil vessel is re- 

 stored to its proper situation, as in Fig. 8. this hole will 

 be immersed beneath the surface of the oil in the little 

 cup which contains the burner, so that it can only af- 

 ford the oil as fast as it is consumed. Lord Cochrane 

 has two patents for these lamps, taken out in 1813, and 

 they are used to great advantage in some districts in 

 London, (j. r.) 



