OCR Text |
Show ' -' - N' Speed of Rattlesnake's . Vibrating Tail Recorded How fast does a rattlesnake's tail ribrate when it is excited? Such was Lhe problem that Mabel C. Williams of Lhe State university of Iowa set her-self her-self to solve. Prof. PI. Jl, Dill, curator jf tho natural history museum let her 3.perlment with the tail of a diamond aack rattle from Texas, with nine or :e'n remaining rattles, others bavin? 3een broken off. Miss Williams re-ions re-ions the results to Science. Two assistants kept the snako's icad out of mischief and handled lhe ecordlng apparatus, while Miss Wii-iams Wii-iams held the tail as. far back from he tip as possible and directed a wire ;he had fastened to it against a brass liate. The touching of tho plate corn-doted corn-doted an electric circuit which record-?d record-?d the vibrations upon a time Indicator. Indi-cator. Then they made the snake angry md it began rattling. The speed of he vibrations of its tail varied from iS to 3U hundredths of a second. The rattling produces a tone which lepends not upon the vibration Vut lpon the natural resonance of the attles themselves. "The pitch of the tone," 'rites Miss fVillianis, "as determined by two musi cians with a very keen sense of pitch, and checked with accurately tuned forks, is between C and C sharp: the tone is expressed therefore, by nbout 128 to 135 vibrations per second. Very marked changes In rate of tail, from the fastest lhat could be produced by marked provocations, to no almost quiescent state, did not causo "V fluctuation fluc-tuation of the pitch beyond this approximate ap-proximate half tone. The tone itself is exceedingly complex, however, -nJ it might conceivably vary with the number and size of the ratL'es. It is possible to detect, but not to identify, certain overtones. "The popular impression that the rattler uses his rattles as a warning lhat he is about to strike is regarded by Mr. Dill as quite erroneous. This snake when striking normally does so first and rattles afterward, if at all. It will, for instance, strike at a bird placed in the cage, rattle, then strike again. It appears that the rattle is rather to terrify than to warn. It is also used as a defensive mechanism. The instinct to vibrate the tail is not peculiar to the rattlesnake, but is common com-mon to many other species, as, for instance, in-stance, to the non-venemous kiuq snake and lhe blue racer." |