LECTURES. 45 
flame by the sound would be thus accounted for. The lecturer 
concluded by saying that flames of gas issuing at the ordinary pres- 
sure of the gas mains might be made sensitive thus: let the gas 
issue from a pin hole burner, or from a piece of glass tube drawn 
out so as to have a small opening, fix a piece of iron wire gauze a 
few inches above the burner, and light the gas above the gauze, 
The gas would only burn above the gauze, and by trial a position 
is readily found, for which the flame becomes sensitive to high 
sounds. 
The Lecture was illustrated by a series of admirable 
experiments. 
