48 Mr. Ainger on the Illumination of Theatre^. 



of the adjacent reflectors, and blend the whole into one undis- 

 tinguishable mass. If, for example, an eighteen-inch parabola 

 be generated, having the distance between the vertex and 

 focus three inches, and if the diameter of the flame in that 

 focus be upwards of an inch, the cone of rays issuing from 

 such a reflector will have at its apex an angle of more than 

 twenty degrees. The light thus thrown on the performers 

 would, I think, be greater than could be obtained from twenty- 

 seven equal flames in the situation of the foot-lamps ; for, if 

 lines be drawn from the place of the foot-lights to the average 

 position of the actors, it will be evident how extremely small a 

 sector of the sphere of rays proceeds in an available direction ; 

 while, in the proposed arrangement, nearly every ray, with 

 only so much loss as is occasioned by the imperfection of the 

 reflecting surface, would be directed exactly to the required 

 points. 



The panels in the remaining three quadrants might be sup- 

 plied with inferior lights and reflectors ; and the glass would 

 be ground, to diffuse the light over the house, and to improve 

 the appearance of the dome when seen by the audience. The 

 change from the ground to the unground glass would be visible 

 only to a small part of the house ; and though, as far as it 

 goes, it would be a defect, it is not, I think, to be put in 

 competition with its numerous and important advantages. 

 It is not, indeed, impossible that the light would be found 

 sufficiently strong to allow of the glass from C to C being 

 slightly ground, by which every objection would be obviated. 

 If this be not practicable, the defect would be seen only when 

 expressly looked for, and would be merely a slight exaggera- 

 tion of the effect which would be produced upon a similar 

 dome exposed to the sun's rays, which might be nearly verti- 

 cal on the one side, and wholly excluded from the other. The 

 variations of light required upon the stage would be managed 

 with much greater beauty and effect, than when a rising or 

 setting sun is seen to be accompanied by the rising or sinking 

 and smoking of a hundred artificial flames. 



It will, perhaps, be doubted whether a light, such as I have 

 described, would extend over a sufficient portion of the stage: 

 such a doubt will exist only with those who are unaware how 



