DEAGAN tuning fork

This is an 'industry standard' tool, manufactured by the J. C. Deagan Company of Chicago, who were the preeminent manufacturer of a *wide* variety of tuned percussion instruments and related equipment in the early half of the 1900's at least. Tuning forks like this are used to set a precise A=440hz pitch for all sorts of musical instruments and/or groups thereof at least historically speaking...nowadays I suppose little electronic gizmos serve the same basic purpose. (without requiring nearly as much skill also, but...these modern times...<groan>)

To use it, one gently strikes one side of the fork end on something (preferably a semi-soft thing, like one's knee -- really!) that makes it vibrate (read: ring, in a way) then placing the ball end of it against a solid surface will transfer the tuned vibration into an audible "note", which you then use as a reference to tune or pitch something else against. (does all that make sense?)

I don't know how old this one really is (nor how to tell an older one from a newer one?) but can say it came to me "handed down" (kinda) from another colleague along with a group of other things, as old pipe organ tools can tend to do. :-)

https://www.google.com/search?q=using+a+tuning+fork&sxsrf=ALeKk007c2i6RUDhj1I9F8HoRMHF3m78Eg%3A1618971912556&source=hp&ei=CI1_YIyRH4m2swWs6JBQ&iflsig=AINFCbYAAAAAYH-bGBMK9KZA4UsB11WVtb2Dn62vbpny&oq=using+a+tuning+fork&gs_lcp=Cgdnd3Mtd2l6EAMyAggAMgIIADICCAAyAggAMgIIADICCAAyBggAEBYQHjIGCAAQFhAeMgYIABAWEB4yBggAEBYQHjoICAAQsQMQgwE6BQgAELEDOgsILhCxAxDHARCjAjoICC4QxwEQowI6BAgjECc6BQgAEJECOgoILhDHARCjAhAKOgUIABCGA1D3nwJYv8UCYJ_eAmgAcAB4AIAB5wSIAY8akgELOC41LjQuMS4wLjGYAQCgAQGqAQdnd3Mtd2l6&sclient=gws-wiz&ved=0ahUKEwiMtfytpI7wAhUJ26wKHSw0BAoQ4dUDCAk&uact=5#kpvalbx=_Po1_YN7iOsSLtAbg8rfACw25

https://en.wikipedia.org/wiki/J.C._Deagan,_Inc.

https://deaganresource.com/