SILBER LIGHT 781 



contour of the jacket or casing D follows or corresponds with that of the oil-holder 

 which it surrounds, v is the space between the jacket and the oil-holder : it forma 

 a space or passage for the circulation of air, which enters at the bottom this space 

 or passage, and also through air-holes e, e, formed in the lower part of the casing D. 

 H is a short tube, socket, or ferrule, fitted in the space v, and attached to the oil-holder 

 B and casing to receive the burner or wick- holder c, the wick passing at bottom 

 into the oil-holder B. The burner or wick-holder c, with its key k and chimney, are 

 of ordinary construction ; g, g, are ordinary air-holes at the lower part of the shell 

 of the burner. The lamp rests by the -bottom edge of the jacket or casing D, on a 

 ledge p, fixed on the inside of the frame of the case A ; this ledge thus supports the 

 whole lamp in the case, and the case is closed at bottom by the bottom of the 

 oil-holder B, except at the space v left open between the casing D and the sides 

 of the oil-holder B, for the circulation of air, which bathes the oil-holder as described, 

 keeps it cool, and allows of the light being maintained equal and steady for a 

 number of hours in the case or frame. Air-holes e may be sometimes formed in 

 the sides, and sometimes in the top of the casing or jacket D, as well as in the lower 

 edge thereof. 



Improvements in gas-burners have been founded upon combinations already de- 

 scribed for supplying the flame in the proper place with the precise quantity of atmo- 

 spheric air required for complete combustion. The inventor of this light directs 

 attention to the curious influence exerted by the height of the chimney upon the 

 illumination afforded by a given quantity of gas. If the height of the chimney be 

 increased from 5 to 10 inches, the light produced appears to the unassisted eye to be 

 whiter and better for the change. But when accurately measured by the photometer, 

 we find that the light is actually diminished by one half, and, at the same time, the 

 consumption of gas is considerably increased. A similar influence is exerted by the 

 shape of the chimney ; for if we place the chimney of a common moderator lamp over 

 a gas-burner the same result is obtained. 



Experiment has also shown that there is no gain, as compared with an Argand 

 in the employment of a double flat- wicked or ' duplex ' burner. If we take a duplex- 

 burner, each wick of a given width, and a circular burner of such dimensions that its 

 wick, if cut in two, would be precisely equal to the two wicks of the duplex, and if we 

 test both burners under the same conditions, their illuminating power and consumption 

 will be found to be precisely equal. This simple experiment could not have been tried 

 before the modern duplex-burner was perfected ; for two separate flat burners, each 

 with a single wick, show a totally different result. The bodies of the burners prevent 

 the flames from being brought into sufficiently close approximation. 



Many attempts have been made, all more or less unsuccessful, to burn oils or gas 

 without a chimney, and to convey air to the burner through apertures somewhere in 

 the lantern, and from thence through tubes or chambers to the flames. These attempts 

 are thought by Mr. Silber to have been wrong in principle, because the air-tracks in 

 all of them, however circuitous, have been continuous and unbroken. If we take a 

 rigid tube of whatever form, and twist it into any number of turns or coils, and then 

 blow into it, we shall find that the forcible exit of air at one end will be simultaneous 

 with its forcible entrance at the other. In the same way, a lamp with a continuous 

 air-track, if moving with a train or vessel, is exposed to sudden rushes of air upon the 

 flame ; and, even if standing still, similar rushes will be produced by alterations in the 

 force or direction of the wind, or by any other atmospheric disturbance. The Silber 

 lamp, in the first place, receives its air supply from above, and neither movement nor 

 atmospheric disturbance exerts much influence on the rate at which air descends 

 through an aperture. This rate is mainly governed by that of the escape of the hot 

 air, which has its outlet within the circle of ingress of the fresh supply. The entering 

 cold air is met, a few inches below the aperture which gives it admission, by a solid 

 metal top or inner roof, which becomes heated when the lamp has been burning for a 

 few minutes. A slit at one end of this inner roof allows the slightly- warmed and 

 rarefied air to proceed onwards whenever it can find opportunity ; that is to say, just 

 as rapidly as the exit of the exhausted or consumed air makes room for it. On its 

 course it passes over the receptacle in which the supply of oil is stored, and keeps this 

 at a moderate and regulated temperature ; then between this receptacle and the inner 

 side of the outer part of the lamp ; and, lastly, beneath the chamber to which the 

 burner is fixed, from whence it finds admission to the flame. The height of the wick 

 is regulated without opening the lantern ; and these lanterns having no opening at 

 their lower part, are especially valuable for use on board ship. You will observe that 

 there is no possibility under this arrangement of a continuous current of air driven in 

 any one direction, but that the air can only diffuse itself gradually, and in proportion 

 to the room made for it, through a succession of chambers which effectually break up 

 its continuity. Moreover, the capacity of the chamber is so calculated that no more 



