142 Management of Light in Illumination. 



Fig. 3, Plate VII., represents a vertical section, of 

 the full size, through the middle of the upper part of 

 the lamp, and in a line passing through the middle 

 of its handle. 



The vertical tube b is 5 inches in length and 

 ij inches in diameter. The burner m, n, is fixed in 

 the axis of this tube by means of the short horizontal 

 tubes o, p, which are soldered to the burner, and like- 

 wise to the inside of the tube b. 



The rack which serves to move the wick is placed 

 within the tube b, by the side of the burner ; but it is 

 not represented in the figure. 



The glass chimney is placed in the upper part of the 

 tube b ; and, in order that it may be firmly fixed in its 

 place, an elastic hoop, made of tin covered on both 

 sides with soft leather, is first pushed down into the 

 opening of the tube b, and the lower extremity of the 

 glass chimney is forced down into this hoop. This 

 hoop is one inch wide ; and, when it is in its place, it 

 rests on the tubes <?, p. The hoop of tin is not sol- 

 dered together ; and, in order to render it more elastic, 

 it has a number of vertical slits, which extend from the 

 upper side of the hoop to within one quarter of an inch 

 of the lower side of it. 



This hoop, covered on both sides with soft leather 

 (such as is used for making ladies' gloves), is about 

 one tenth of an inch in thickness, so that its diameter 

 within is one inch and three tenths, which is also the 

 diameter of the glass chimneys below, or of that por- 

 tion of them which enters the hoop. 



The tube b is made larger than otherwise would be 

 necessary, in order to receive this elastic hoop, which 

 has been found to be very useful for fixing the glass 

 chimney firmly in its place. 



