86 Of the Management of Fire 



ing sight, I caused a glass window to be made in the 

 front wall of the fire-place, through which I could look 

 into the fire when the fire-place doors were shut ; and 

 I was well paid for the trouble and the trifling expense 

 I had in getting it executed. 



Some may be tempted to smile at what they may 

 think a childish invention ; but there are many others, 

 I am confident, and among these many grave philoso- 

 phers, who would have been very glad to have shared 

 my amusement. 



The window of which I am speaking is circular, and 

 only 6 inches in diameter ; but as the hole in the wall 

 is conical, and much larger within than without, the 

 field of this window (if I may use the expression) is suf- 

 ficiently large to afford a good view of what passes in 

 the fire-place. 



This conical hole is represented in the Figures 18 

 and 2 1 by dotted lines. It is situated on the left hand 

 of the entrance into the fire-place. Into the opening of 

 the hole in the wall, on the outside of it, is fixed a short 

 tube of copper (about 6 inches in diameter, and 4 inches 

 long) ; and in this tube another short movable tube is 

 fitted, one end of which is closed by the circular plate 

 of glass which constitutes the window. As the wall of 

 the fire-place in front is thick, this pane of glass is at 

 a considerable distance from the burning fuel, and, as 

 there is no draught through the hole in the wall, the 

 glass does not grow very hot. 



I have been the more particular in my description of 

 this little invention, as I think it may be useful. There 

 are many cases in which it would be very advantageous 

 to know exactly what is going on in a closed fire-place, 

 and this never can be known by opening the door ; for 



