Burning Gas for the purpose of Illumination. 297 



stead of hanging the gallery on the bui-ner, it should be placed 

 beneath it, and fixed by screwing down the burner on it. In 

 this case, it is necessary to give the gallery an increased dia- 

 meter, as the air, both for the inside and the outside of the 

 flame, must enter through its ribs. The bm*ners should also 

 be made conical instead of cylindrical ; but this is not so im- 

 portant as drilling them with numerous holes, — at least double 

 the number usually allowed, as the closer they are the better, 

 the expenditure being regulated by the stopcock, and not^by 

 the number of holes. 



In making the galleries, great attention should be paid to 

 having the rim and seat for the glass truly concentric with the 

 hole through which the nozzle-screw, on which the burner is 

 fixed, passes ; the workmen should have a solid wooden chuck 

 of the size of the bells of the chimney-glasses, and should chuck 

 the galleries on it, in order to drill the aperture through which 

 the nozzle-screw is to pass. The outside and inside faces of 

 this hole should at the same time be turned true, as, if this 

 be done with the proper care, the glass, the burner, and the 

 gallery, will all be true to the same axis, when they are put 

 together and screwed up. The hole through the gallery 

 .should not be tapped, as the burner is sufficient fixture for it 

 when screwed down over it. If this part of the work be well 

 executed, even an indiff'erently made burner will perform well, 

 and if it be ill done, the best bm-ner will appear defective, 

 and be liable to break the glasses. 



The arrangement of burner and gallery here recommended 

 Is not incompatible with the use of plain cyhndric glasses, but 

 it will be found better to use what is sometimes called the 

 French-shaped chimneys, that is, those which are used with 

 the common ai'gand oil-lamps. The wideness of their mouths 

 gives them a firm seat in the gallery, and if the length of the 

 bell, or wide portion of the glass, be such that the neck or 

 choke shall be on the level of the lip of the burner, and the 

 upper part of the glass be four inches to four inches and a 

 half long, then a favourable result will be obtained. It is ex- 

 pedient to obscure the lower part or bell of the glass, as the 

 burner is thereby concealed, and the flame appears to rise out 

 of a thick wax-candle. No moon-shades should ever be used, 



