102 On the Sinumbra Lamp. 



reservoir as described in Plate I. 2, figure B.B. and the peculiar 

 application of the frosted glass light-distributor. 



The combination of these two improvements destroys all 

 shadow, as will be explained. 



The second is effected by the total enclosure of the flame in 

 the frosted glass light-distributor, which refracts the light into 

 innumerable radiations, each proceeding from one of an inde- 

 finite number of small fractures or stars given to the glass in 

 the act of roughing or frosting it. Each one of these fractures, 

 when examined by a microscope, is a small star, from which the 

 light radiates as from a new centre of illumination, and pro- 

 duces what is called a soft light. The expansion of the dis- 

 tributor is sufficient by the radiation from these stars to over- 

 come the shadow otherwise projected from the ring oil-reservoir, 

 which in experiment we find it completely effects. 



The last desirable object to attain in a perfect lamp, is to 

 command a powerful, agreeable, and equally-diffused light im- 

 mediately underneath it, diverging at an angle from the flame 

 so as to illuminate a table around which ten persons can com- 

 fortably dine, and at the same time to light the upper part of the 

 room and the persons sitting round the table. This is effected 

 in the lamp before us in a very perfect manner. 



In the centre of the frosted glass light-distributor a burnished 

 metallic reflector is placed on the glass chimney, by metallic 

 springs, close to the flame, and rather above its centre, 

 which reflects some of the brightest light on the table, still 

 leaving a sufficiency for illuminating the upper part of the room. 

 By these means the light of two French lamps is obtained on 

 the table, without any additional consumption of oil, or any 

 glare injurious to the eyes. Thus we have in this lamp, a 

 strong and at the same time, if we may use the expression, soft 

 and delicate light, where most desirable ; we have no shadow 

 from any of its apparatus, and a light the least injurious to 

 the eye that has yet appeared. 



Explanation of the Plate. 



(A) The centre of illuminatioD. 



(B) The Ring Oil Reservoir, the upper and lower surfaces of which are 



shaped to conform with the direction of lines radiating from the 



