Galton_whistle.jpg
Summary
Description Galton whistle.jpg |
English:
A
Galton whistle
, the first
ultrasonic
whistle
or "dog whistle".. It was invented in 1876 by
Francis Galton
and used to test the hearing range of various animals. It consists of a whistle blown by the rubber bulb, with a small sound chamber whose size can be accurately adjusted by a plunger attached to a
micrometer
. The micrometer can be calibrated to give the frequency in hertz.
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Date | |
Source | Retrieved March 12, 2014 from H. Winfield Secor, "Oddities of Sound" in The Electrical Experimenter magazine, The Experimenter Publishing Co., New York, Vol. 8, No. 2, June 1920, p. 153, fig. 13 on http://www.americanradiohistory.com |
Author | H. Winfield Secor |
Licensing
Public domain Public domain false false |
This media file is in the
public domain
in the
United States
. This applies to U.S. works where the copyright has expired, often because its first
publication
occurred prior to January 1, 1929, and if not then due to lack of notice or renewal. See
this page
for further explanation.
|
||
This image might not be in the public domain outside of the United States; this especially applies in the countries and areas that do not apply the
rule of the shorter term
for US works, such as Canada, Mainland China (not Hong Kong or Macao), Germany, Mexico, and Switzerland. The creator and year of publication are essential information and must be provided. See
Wikipedia:Public domain
and
Wikipedia:Copyrights
for more details.
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