99 I^i* Ure on the Btale Idght 



argand gas flame is of a blue tint for fourteen-sixteeuths Of an inch, a 

 space in which the gas burns with intense heat, but little or no light ; 

 whereas the base of the Bude flame acquires a dazzling whiteness at three- 

 sixteenths of an inch from the metal. Thus we see, that, through a range 

 of eleven-sixteenths of an inch, the common gas argand flame is wasted 

 in producing the nuisance of heat without light. 



Secondly. — From the phenomena just noticed, as also from the circum- 

 stance of the Bude flame emitting a double light with a single volume of 

 gas, when compared with the gas argand, it is manifest that the former, 

 in equal degree, can disengage at the utmost only half the heat that the 

 latter does. 



Thirdly. — The Bude light simplifies greatly the means of artificial illu- 

 mination, since it concentrates in one flame as much light as Avill diffuse, 

 throughout a large apartment, a mid-day lustre, which may be softened 

 by shades of every hue, and reflected by mirrors in every direction. 



Fourthly. — From this property proceeds its value ds a ventilator, since 

 the single tube which carries off" the burned gases serves to draw out also 

 the effluvia from a crowded chamber. 



From all these facts, I am of opinion that Mr Gurney's new Bude light 

 is a most meritorious invention in reference to both public and private 

 buildings, as it removes altogether the objections hitherto justly urged 

 against the use of the highly hydrogenous gas of the London companies 

 in dwelling-houses, namely, that its heat is great in proportion to its light, 

 when compared with the more highly carburetted gases of Edinburgh and 

 Glasgow. 



The time must therefore be now at hand when the great economy and 

 convenience of lighting private houses with gas will be experienced by 

 the inhabitants of the metropolis; as they have been for such a considerable 

 time by those of every town of importance in Scotland. 



That the same quantity of coal-gas may be made to produce a double 

 amount of illumination in Mr Gurney's patent burner to that obtained from 

 it in an ordinary argand, will appear to many a paradoxical, if not a 

 doubtful, proposition. Of its reality, however, I am fully convinced, and 

 I think the fact may be accounted for in the following way : — 



Light, in general, is proportional to the intensity of ignition, a truth 

 well exemplified in the effect of the oxy-hydrogen flame upon a bit of 

 lime or clay. On the same principle, when the flames of two candles are 

 brought into close contact, they aflbrd a compound light considerably 

 greater than the sum of their separate lights. Now, Mr Gurney's burner 

 gives such a compound flame. It consists of two or more concentric cy- 

 linders of flame, mutually enhancing each other's temperature, just as in 

 Fresnel's polycycle oil argand lamps used in the French lighthouses. 



In addition to the augmented intensity of ignition, we must also take 

 into account the peculiar nature of the combustion of carburetted hydro- 

 gen gas, whether as generated from coal in a retort, or from oil in a lamp. 

 The vivid whiteness of its flame is due to the separation in soHd particles, 



