Metal object with glass insert

[neodetectorist]

I found this piece MDing this evening. I looks to be a cast iron from the rusty nubs on it.
It has a glass insert.
One end has a hole and the other is tapered to a point where maybe a small hole is?
It reminds me of a hose nozzle but due to the glass insert, maybe held gas or petroleum but that is just a guess.
Here are some pictures.





What is this?

 

[pepperj]

The glass insert would be used as a fluid sight glass. There also might be a type of pressure gauge and there would a rule/numbers for reference.

 

[releventchair]

Could be an oil fill level sight glass from a gearbox or hydraulic reservoir.
Had similar on industrial equipment.

 

[villagenut]

Part of a pet cock. or I should have said....part of the assembly that had a petcock valve on it. Here is one in brass that I dug many years ago. From a small steam or hit and miss engine.

 

[Tony in SC]

Could be an oil level site glass from the crankcase of a very early vertical engine, hit & miss time frame. Could be IHC. Worth a few bucks.