4 Dr. R. Konig on Manometric Flames. 



flames the length of only 8 to 10 millims., on sounding the fun- 

 damental the middle flame will be extinguished, on sounding the 

 octave the exterior ones will disappear. 



These experiments may also be made with a closed organ- 

 pipe which can be sounded on its fundamental and its first over- 

 tone. One of the flames must then be at the end of the pipe, 

 where the node of the fundamental, as well as one of the nodes 

 of the overtone, are found. 



If the flame be shortened, on sounding the fundamental the 

 end flame will be the first to go out, aud then the middle one, 

 because the latter is nearer to the node than to the ventral 

 segment in the mouth of the pipe. 



But on sounding the first overtone, the 12th of the fun- 

 damental, the middle flame remains unchanged, while the two 

 exterior ones become extinguished. 



Comparison and Combination of several Tones. 



These experiments have only shown the general working of 

 whole series of consecutive vibrations ; if, however, we allow the 

 flame to be reflected by a rotating mirror, we see all phases of 

 their motion side by side, and we can then not only examine the 

 number of vibrations and the ratios of different tones, but also 

 observe the images made by the combination of several tones. 



The apparatus which serves for these investigations consists 

 of a set of organ-pipes, each of which is provided at the node of 

 its fundamental with a manometric capsule. This can be con- 

 nected by means of an india-rubber tube with gas-burners, which 

 are placed on a special stand (fig. 2). 



Before these gas-burners there is placed a revolving mirror, 

 made of four glass plates coated with platinum. The platinum 

 surfaces are turned outwards, in order to avoid the confusing 

 double images of the common mirrors, which is caused by re- 

 flection from the two surfaces of the glass plates. A small wind- 

 chest, for the reception of two organ-pipes, has two mouth- 

 pieces, the larger of which serves to conduct the air from a 

 bellows. Through the smaller one the gas is conducted to a com- 

 mon receiver, provided with two cocks, which are joined by means 

 of india-rubber tubing to the capsules of the organ-pipes. 



The reflection of a flame at rest shows in the rotating mirror 

 a band of light of the width of the height of the flame. If we, 

 however, sound the organ-pipe in connexion with it, there 

 appears in place of the band of light a series of regularly con- 

 secutive flame-pictures, the tips of which are bent in a direction 

 opposite to that in which the mirror is moving. 



If we place two burners in such a position that their reflections 

 give two bands of light, one above another, and connect them 



