<< >>
Usage conditions apply
This incomplete radiosonde is of the type Pazel Moltchanoff introduced in 1930. Sensors for the measurement of temperature, pressure, and humidity were connected by linkages to arms that moved in response to changing meteorological conditions. The position of these arms was codified by a series of contacts that resembled four nested offset combs, which is why the radiosonde was known as the Kamm-geraet, or "comb-apparatus." The sensor arms could only contact one tooth of any one comb at a time. This contact enabled on-off keying of a radio signal, which corresponded to one of four Morse code letters (e, i, s, h) that were produced by a set of cams with 1, 2, 3, and 4 points that were spun by an external windmill. (A rising temperature produced the Morse signal e-i-s-h, and a falling temperature h-s-i-e.)
J. L. Dubois, R. P. Multhauf, and C. A. Ziegler "The Invention and Development of the Radiosonde with A Catalog of Upper-Atmospheric Telemetering Probes in the National Museum of American History, Smithsonian Institution", p.33-38. (
K. O. Lange "Radio-meteorographs," The Bulletin of the American Meteorological Society 16 (1935) p.267-271.
Currently not on view
Object Name
overall: 13 in x 10 1/2 in x 2 5/8 in; 33.02 cm x 26.67 cm x 6.6675 cm
overall; radiosonde: 13 in x 14 1/2 in x 10 in; 33.02 cm x 36.83 cm x 25.4 cm
overall; cover: 10 1/8 in x 9 1/8 in x 2 5/8 in; 25.7175 cm x 23.14575 cm x 6.6675 cm
ID Number
catalog number
accession number
See more items in
Medicine and Science: Physical Sciences
Data Source
National Museum of American History
Nominate this object for photography.   

Our collection database is a work in progress. We may update this record based on further research and review. Learn more about our approach to sharing our collection online.

If you would like to know how you can use content on this page, see the Smithsonian's Terms of Use. If you need to request an image for publication or other use, please visit Rights and Reproductions.


Add a comment about this object