What is this? Made of brass. The handle swivels .

[bigindian]

 

[CoilyGirl]

Looks like a latch to a window.

 

[Ant]

Looks like the thumb lever on one on these to me:
https://images.search.yahoo.com/search/images;_ylt=A0SO8xzSUyBV4lMA15Jx.9w4?p=antique+bicycle+thumb+bell&fr=&fr2=piv-web&psqn=2

 

[bigindian]

Hmmm. Ok thanks guys.

 

[nhbenz]

Hmm, both good ideas, but it appears to have been mounted on a pole (or something cylindrical), and then the lever would be... Adjusting it somehow?

 

[kingskid1611]

I was thinking that it may be a Morse code piece.

 

[RelicDude]

Could be part of a valve off a musical instrument like a clarinet or saxophone.

 

[trdking]

I was thinking more of a stop click for an umbrella to hold it in the up position

 

[2Minnesota]

Could it be a part off an old sprinkler? Image from http://static.fastline.com/assets/item/048/062/52622565-d109-4ea4-87d9-616097f0ddef.jpg.

 

[cudamark]

Hmm, both good ideas, but it appears to have been mounted on a pole (or something cylindrical), and then the lever would be... Adjusting it somehow?

i agree. Looks to me like a slide valve that regulated the amount of air going into or out of a small diameter tube. Maybe for a burner, torch, or the like.

 

[on.off]