222 ANNUAL RECORD OF SCIENCE AND INDUSTRY. 



son with Schciblev's forks, it is found that the former gives 

 435.875 double vibrations per second, or nearly one vibra- 

 tion more than is assigned to it by the report of the commis- 

 sion. Lissajous determined this pitch by means of the im- 

 proved Latour siren. 



Terquem shows very elegantly the phases of a vibrating- 

 plate by placing a wide-mouth bell-jar over the plate, con- 

 necting the jar with one of Konig's manometric flames. If 

 the axis of the bell be exactly over the centre of the plate, 

 the flame is entirely unaffected; so, also, if symmetrically 

 placed over a nodal line. When the bell is displaced even 

 slightly, the flame shows serrations, which reach a maximum 

 when it comes over a ventral segment. The experiment 

 may be modified by using two smaller bell-jars, connected 

 to the same capsule by a Y tube, a sliding tube being placed 

 on one of the branches for adjustment. In this way the ser- 

 ration of the flame may be made very strong, being the sum 

 or difference of the separate segments according as the bells 

 are placed over alternate or adjoining portions. The gas 

 jet used is made more brilliant by carbonizing the gas be- 

 fore burning, and by enclosing it in a tube through which a 

 current of oxygen is passed. A cylinder of mica, blackened 

 except opposite to the flame, surrounds the outer tube. 



Blaikley has contrived a simple method for experimental- 

 ly determining the position of the nodal points in tubes of 

 varying section a matter of great importance in the theory 

 of brass musical instruments. For example, given a conical 

 tube open at both ends r whose pitch is C 512 vibrations. 

 The node is nearer the small end, and by sinking one end in 

 water and holding a fork of the pitch of the tube over the 

 other, the exact position of the node is shown by the level 

 of the water at maximum resonance. 



Gordon has proposed an extremely simple form of phonei- 

 doscope, free from the defects of the ordinary instrument. 

 All the apparatus required is the hand and some soap-suds. 

 The forefinger and thumb being bent so as to form a circle, 

 a soap film is drawn across them with the other hand. By 

 turning the wrist the angle made with the direction of the 

 light may be readily adjusted, a motion of the elbow alters 

 the distance from the mouth, and the tension of the film can 

 be exactly regulated by moving the thumb and finger. On 



