112 



UNDULATORY FORCES. LIGHT. 



[THE BCDB LIGHT. 



Pig. Ill 



6 



been brought partially into use."* Fig. Ill repre- 

 sents Keir s lamp, the vase and pedestal of which are 

 hollow, a is a tube into which a certain quantity of 

 Kii . Hi. salt and water, having three times the spe- 

 : i oifio gravity of oil, is put. Upon this is 

 . T*t . poured the oil until the tube U full. The 

 / \ brine, or solution of salt in water, runs 



down into the pedestal of the lamp ; and 

 wlirii the oil" is poured upon it, the hitter, 

 by its weight, forces up the former through 

 second tube 6. into a chamber , in the 

 upper part of the body of the lamp, and 

 the oil takes the place of the brine in the 

 pedestal It will be noticed that the tube 

 a reaches only to the top of the chamber in 

 the pedestal, while the tube b passes down 

 to the bottom of it. The brine is repre- 

 sented by diagonal lines, and the oil by 

 dots. Now, in consequence of the great weight of the 

 brine, as compared with that of the oil, the latter is 

 forced up to the burner as fast as it is consumed ; and 

 thus, by a sort of natural spring, the flow of oil to the 

 wick is constantly maintained. After a supply of salt 

 and water has once been introduced into the lamp, there 

 is no necessity for a further addition of it. 



Similar lamps have been constructed on 

 the same principle by King, Barber, and 

 others ; but they are all difficult to manage, 

 and hence they are not much in vogue, 

 although they generally have a very light 

 and elegant appearance. 



(.) Parker's Fountain Lamp (Fig. 112) is 

 a very complicated apparatus, which, like 

 the fountain of Hiero, owes its action to 

 compressed air. Externally it presents the 

 appearance of a column surmounted by 

 the lamp ; but within this column there is 

 another cylinder which contains the oil. 

 This cylinder must be removed before the 

 lamp can be charged. It is divided cross- 

 wise into three compartments, a b c, which 

 have no direct communication with each 

 other. Through the centre of the whole 

 there passes a tube /, which is open at its 

 top, and at the bottom it communicates by 

 a sort of valve with the compartment c ; it 

 also communicates with the compartment 

 ii. by means of a hole which is seen near 

 . the top of the tube. The three compart- 

 ments or chambers are therefore in indirect 

 communication with each other; thus a communicates 

 through the hole just mentioned with the tube /; this 

 communicates by its bottom valve with compartment c ; 

 and this, by means of a tube and valve g, with the 

 middle compartment b ; and 6 communicates by means 

 of an ascending tube with the burner i, in wliich the 

 wick is placed : so that if oil be poured into the upper 

 opening of the tube /, it will fill the compartment c ; 

 and then, on turning the apparatus upside-down, the oil 

 will flow through g into the middle compartment 6. On 

 restoring the cylinder to its proper position, the oil 

 cannot return to c, because of the peculiar form of the 

 contrivance g consequently it remains in the middle 

 chamber; and now, on refilling e through the tube /, 

 the air in the lowest chamber is compressed, and it 

 forces the oil in 6 up through the lateral tube to the 

 burner i. The chamber a is filled at the same time as/, 

 and its contents flow as fast as they are wanted through 

 the hole in the tube /, and thus keep up a supply to the 

 pressure-column. Every time the lamp is charged it is 

 inverted, in order that the oil in c may flow into 6 ; and 

 then it is returned to its original position, and recharged 

 with oil This lamp was reported on by the French 

 Academy of Science, and it was formerly much used in 

 India ; though now it is superseded by the Iris lamp. 



(k.) The Cared Lamn presents much of the appearance 

 of the hut described ; but instead of the flow of oil being 

 effected by means of atmospheric elasticity, it is accoin- 

 Wrtxter and Parker, p. 149. 



f 



: 



lished by the aid of machinery moved by clock-work. 

 11 this way the oil is raised, or rather pumped up, to 

 the wick, so as to keep up. a constant supply by conti- 

 nually overflowing it The oil drips back into the 

 cistern below ; whence it is drawn up repeatedly, until 

 it is all consumed. 



(/. ) The Solar Lamp. This is Roberta's great improve- 

 in. lit on the Argand, although it was patented by Mr. 

 Bynner. It b a contrivance for increasing the supply 

 of atmospheric air to the flame, and no enabling it to 

 consume a larger proportion of oil, and thus to give out 

 a greater body of light ; besides wliich, it effects a more 

 complete combustion of the oil, and therefore produ es 

 a more intense light In all the common forms of Ar- 

 gaud, the air passes straight 

 up through the burner, and 

 only slightly impinges on the 

 two sides of the flame ; but in 

 this contrivance the current 

 of air is broken, and made to 

 blow in upon the flame. The 

 apparatus which effects this 

 is a small cone or nipple, that 

 is dropped down over the 

 flame (Fig. 113). 



A still greater improvement 

 on this principle is that of Quarrel, in wlr'ch he causes a 

 second current of air to enter under the glass, and thus 



\f. 



Fig. 114. 



fig. 115. 



to assist the other in 

 blowing on the flame 

 (Fig. 114) ; and by intro- 

 ducing a button into the 

 centre of the flame (as 

 was also originally pro- 

 posed by Mr. Roberts), 

 this inner current of at- 

 mospheric air is likewise 

 deflected, and thus we 

 get the greatest possible 

 amount of oxydation 

 (Fig. 115). By the adop- 

 tion of such contrivances 

 as these, almost any kind of oil, even the commonest 

 fish-oil, may be burnt without producing any unpleasant 

 smell. 



(TO.) The Bude Light of Mr. Goldsworthy Gurney is 

 only an extension of the preceding principle. Roberts 

 increased the supply of atmospheric pxygen by IIMMII; 

 of the nipple, which others patented and applied to the 

 solar lamp. Mr. Gurney, however, uses a jet of pure 

 oxygen, or of an atmosphere rich in oxygen, which he 

 tlirows into the centre of the flame by mechanical power ; 

 and by tliis means he increases combustion and light to 

 an enormous extent. This light requires complicated 

 apparatus for its production, and hence it has never 

 come into general use. 



(n.) The Argand with Concentric Wicks. Many years 

 since, Mr. Webster suggested that Argands might be 

 made with two circular wicks, one within the other ; and 

 Sir Humphry Davy referred to the invention as one 

 well adapted for obtaining heat for chemical purposes. 

 A lamp on the same principle, with four concentric 

 wicks, has since been constructed by M. Fresnel, for 

 lighthouses ; and, according to Dr. Brewster, it gives a 

 light equal to forty common Argands ; but the heat pro- 

 duced by the lamp is very intense. 



5. Lamps for Burning Solid Fats. The commonest 

 form of these is the saucer and central-wick lamp, which 

 may be seen so frequently in France during the nights 

 of illumination ; but a more agreeable form has been 

 given to this kind of lamp by the Hon. G. Cochrane, 

 who took out a patent for it a fow years ago. His lamp 

 is very much like an ordinary Argand, but it has a piece 

 of metal over the flame which communicates with the 

 chamber containing the fat, and thus keeps it warm and 

 liquid (Fig. 116). The fats which are best suited for this 

 lamp are cocoa-nut and palm ; but tallow and kitchen- 

 stuir may also be usi-.l. 



'>. Camphine or Vesta Spirit Lamps. These are the 



