ENTOMOLOGY 



obtained at first twenty, and later one hundred and ten, successive photo- 

 graphs per second of a bee in flight. As the wings were vibrating 190 

 times per second, however, the images evidently represented isolated and 

 not consecutive phases of wing movement. Nevertheless, the images 

 could be interpreted without difficulty, in the light of the results ob- 

 tained by other methods. At length he ob- 

 tained sharp but isolated images of vibrating 

 wings with an exposure of only Y O~TT o~o f a 

 second. 



The frequency of wing vibration may be 

 ascertained from the note made by the wing 

 if it vibrates rapidly enough to make one; 

 and, in any case, may be determined graphic- 

 ally by means of a kymograph, which, in 



one of its forms, consists of a cylinder covered with smoked paper and 

 revolved by clockwork at a uniform rate. The insect is held in such 

 a position that each stroke of the wing makes a record on the smoked 

 paper, as in Fig. 74. Comparing this record with one made on the same 

 paper by a tuning-fork of known vibration period, the frequency of wing 



FIG. 



73. Trajectory of 

 wing of an insect. 



the 



FIG. 74. Records of wing vibration. A , mosquito, Anopheles. Above is the wing record 

 and below is the record of a tuning-fork which vibrated 264.6 times per second. B, wasp. 

 Polities. The tuning-fork in this instance had a vibration frequency of 97.6. 



vibration can be determined with great accuracy. As the wing moves in 

 the arc of a circle, the radius of which is the length of the wing, the ex- 

 treme tip of the wing records only a short mark; if, however, the wing is 

 pressed against the smoked cylinder, a large part of the figure-8 trajectory 

 may be obtained, as in Fig. 74, B. The wings of the two sides move syn- 

 chronously, as Marey found. 



