On Tue, 27 Feb 2018 05:02:57 +0100, Emanuel Berg
wrote:

Jeff Liebermann wrote:

Besides hygrometer, a humidity meter is also
called a psychometer, psychrometer, or
various trade names (i.e. Psychron).
Here's my Bendix Psychrometer Model 566-3:
http://www.LearnbyDestroying.com/jeffl/pics/weather%20stations/Bendix%20Psychron%20566/index.html
It's a nifty little instrument and state of
the art for the 1960's.

1960s? Sounds like an 1880s Jule Verne novel...

Hardly.
https://en.wikipedia.org/wiki/Hygrometer
The early hygrometers used a human or horse hair, which changed length
with the RH. The wet/dry bulb (psychrometer) was invented in the
early 19th century. That morphed into the sling psychrometer:
https://www.google.com/search?q=sling+psychrometer&tbm=isch
which earned me an afternoon at the local police station while they
attempted to identify the type of weapon I was swinging around. Todays
motorized and electronic wet/dry bulb contraptions are improvements on
the basic design. Capt Nemo probably had one aboard the Nautilus as
too much or too little humidity in a closed environment tends to do
bad things to men and machines.
https://books.google.com/books?id=vicCAAAAYAAJ&pg=PA703&lpg=PA703
Where an accurate psychrometer comes in handy is demonstrating to
buyers of elaborate electronic weather stations that their humidity
measurements are very slow to change, and rather inaccurate.

Make one for about $10 or a wall hanger type for $15.
https://www.teachersupplysource.com/product/61246/scott-resources-hubbard-scientific-sling-psychrometer-kit/
http://www.spectrum-scientifics.com/ProductDetails.asp?ProductCode=3619
http://www.spectrum-scientifics.com/Wall-Thermometer-Wet-and-Dry-Bulb-p/6213.htm

Topic drift at its best...


--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558