THE ARGAND LAMP.] 



UNDULATORY FORCES. LIGHT. 



109 



of keeping the wicks equally well trimmed. To obvi.itf 

 this, the flat wick was invented ; and thus a thin sheet o 

 flame was produced, which allowed of much more perfec 

 combustion. Nevertheless, with all these improvements 

 the light of the lamp could not be increased beyond 

 certain point, without its becoming dull and the wicl 

 Booty ; and consequently, for many years the lamp was 

 rarely used in the apartments of the rich, for fear of i 

 doing harm to the walls and furniture by its grea 

 tendency to smoke. 



In 1780, however, as we have already said, a grea' 

 change was effected in the art of illumination by the dis 

 covcry of M. Argand of Geneva, who found, that whenever 

 a due supply of atmospheric air was furnished to the 

 inside as well as the outside of a flame, the combustion 

 of the oil might be kept up to any amount withou 

 danger from smoke or bad smell. The plan which he 

 adopted for accomplishing this was very simple. He 

 made the wick circular, and placed a glass around it so as 

 to secure a strong current of atmospheric air to both 

 sides of the flame. We shall have occasion to describe 

 the details of hia contrivance when we come to the 

 subject of the various Argand lamps at present in use. 

 All subsequent improvements on this invention of M 

 Argand, have been with the view of adjusting the wick, 

 of regulating the supply of oil, of doing away with the 

 shadow cast by the reservoir, and of directing the current 

 of atmospheric air into the body of the flame. The first 

 object was accomplished by means of a rack and pinion, 

 or by a point working in the thread of a screw ; the 

 seconil by various forms of fountains, syphons, and, in 

 the C'.ircel lamp, by means of a piston which is worked 

 by machinery. The wick has also been modified in its 

 construction so as to suit the condition of the oil ; it is 

 made of fine web when the oil is very fluid, and of 

 coarse web when it is thick. The third object has' been 

 accomplished by giving the reservoir an annular form 

 this was Count Rumford's invention or by placing it 

 above the level of the flame, as in Parker's lamps ; and 

 the fourth, by contracting the glass immediately around 

 the wick, or by putting a metallic disc into the centre of 

 the flame, as in the Vesta lamp ; or by dropping a brass 

 nipple over it, as is the case with the solar lamp. All 

 these contrivances increase the supply of air; and, by 

 breaking its course, they cause it to impinge upon the 

 body of the flame. 



For the combustion of volatile oils and naphtha, lamps 

 of very different construction are required ; especially 

 in those cases where the oil or spirit is to be consumed 

 in a gaseous form without the aid of a wick. We shall 

 describe these lamps, which are of comparatively modern 

 invention, when we speak of Scale's, HoUaday's, and 

 Liidersdorff s lamps. 



With all lamps, however, the great principle that is to 

 be kept in view is, so to adjust the supply of atmo- 

 spheric air to the combustible, that, on the one hand, the 

 flame shall not evolve smoke, and, on the other, it shall 

 not be cooled or over-burnt ; for, in the one case there is 

 too little atmospheric air, and in the other there is too 

 much. 



Management of Lamps. Lamps will not burn in a 

 satisfactory manner if they are not kept clean and well 

 trimmed ; for, in the first place, nearly all the oils which 

 are made use of at the present time are, more or less, 

 drying in their nature, and consequently they are apt to 

 become thick in the lamp, and to clog its several 

 apertures. Whenever this occurs, the lamp ceases to 

 burn ; and thre is no help for it but a good cleaning. 

 This is accomplished by draining out all the oil as com- 

 pletely as possible, then charging it with a strong 

 solution of soda or pearlash, which combines with the oil 

 and /<>rms soap. This solution ought to remain in the 

 l.-iinji for twmtj-foor hours, and it should be frequently 

 ptaUd ; but care should be taken not to spill any of 

 the liquor over the paint or lacquering of the lamp, for 

 fear of ilUw.Iving it off. After it has stood in this way 

 for the nece.'wary time, the soapy liquid may be run out, 

 then washed clean away with warm water ; and, finally, 

 the lamj) is to be well dried. Some of the verv common 



oils are so liable to resinify, that it is necessary to change 

 the wick every day : this is the case with the oils that 

 are used in Parker's hot-oil lamp, and consequently it is 

 trimmed with a very short wick. In the second place, 

 the wick should be properly attended to : if a solid wick 

 is used it should not be twisted too tight, for f oar of stop- 

 ping the capillarity of the oil ; nor should it be too loose, 

 for then it is apt to accumulate soot. If the Argaud, or 

 hollow wick, be employed, it should be selected with due 

 regard to the quality of the oil ; for a thick or fatty oil 

 requires a coarse texture, and a very fluid oil a fine one. 

 The top, or carbonised portion of the wick, should 

 always be removed immediately before the lamp is 

 lighted ; for this is so changed by the action of heat, that 

 the oil will not rise in it ; indeed, the common oils are so 

 disposed to char and clog this portion of the wick, that 

 it sometimes requires removal several times in the course 

 of an evening. The wick should be cut perfectly level, 

 or the flame will be irregular, and will smoke. Lastly, 

 in cold weather it is advisable to warm the oil before the 

 lamp is lighted. 



The relative Illuminating Poioer and Economy of 

 different Lamps. This is a subject which has not been 

 well investigated ; for the difficulties connected with it 

 are extremely great. At the Exhibition of 1851, there 

 were forty-nine lamps sent for examination; but the 

 jurors declared that it was a matter of impossibility to 

 test their value. M. Peclet is nearly the only person 

 who has devoted attention to this subject ; and the 

 following table is constructed in great part from his 

 investigations 



Luminosity 



Consumption In sperm 

 Lamp*. per hour. candles at 



120 grains. 



Relative 

 power for 



ciiual 



weight. 



140 grains 'JO 



1. Vesta lamp without i 



button (camphine) } 



2. Vesta lamp without 1 



button (with coal- L 

 naphtha) 



3. Common Argand . . 



4. Carcel lamp .... 



5. Sinumbra, with lateral 1 



fountain J 



6. Thilorier's or Parker's 1 



lamp J 



7. Sinumbra, with foun- 1 



tain above J 



8. Common sinumbra . . 



9. Gerard's hydrostatic 



10. Common open lamp . . 



11. Eclairage au gaz . . . 

 L2. Fountain lamp, with 1 



flat wick / 



L3. Dome Argand . . . 



Varieties of Lamps. These are so exceedingly nu- 

 merous, that it is not possible, in a work like the present, 

 K> give anything more than a very general account of the 

 most important. Indeed, there are but few really 

 distinct principles involved in the construction of lamps, 

 lotwithatanding that there are so many modifications in 

 ,heir form and arrangement ; we shall have no difficulty, 

 therefore, in understanding the construction of any lain]), 

 after we have become acquainted with the fallowing 

 rarieties. It is proper to add, that we are indebted to 

 ;he Encyclopaedia of Domestic Economy for many of the 

 llustrations which we are about to offer, and that the 



136 



350 

 MO 



270 

 767 



645 



645 

 699 



103 

 343 



165 



400 



2O 



4-0 

 70 



2-9 



7-6 



63 



6-0 

 4-5 

 0-8 

 2-1 



0-9 

 21 



185 



147 



114 

 111 



109 



99 



98 



91 

 86 



77 

 Cl 



54 

 52 



reader will therein find a very 

 food description of the lamps 

 now in use. 



1. Common Oil Lamp, without 

 any Glass. Of these there are 

 everal : 



(a. ) The Common Lamp of the 

 Shetland and Orkney Islands 

 90). This is contrived for 

 he combustion of common fi.th- 

 il, and the wick that is use ,1 

 nothing more than a bundle 

 f dried rushes. A lamp of 



Fig. 90. 



similar construction i 



