chapman no. 8 miniture jack

I found this at a yard sale and thought it was really odd, I've had the full size ones before but never saw one this small. Any Ideas?
BTW its cast iron and weighs about 11 oz.

 

I've seen those screw jacks used to level castings on a layout table before scribing lines for checking dimensions.

 

Thanks, the closest I've come is Machinist Screw jack but nothing on age etc.

 

Well, patented in 1935 means it's after that. They probably would have dropped the date after twenty years or so.

 

Was looking at an old Chapman screw jack chart and wondering if your's is a #3 - could be the 3 was flattened with use to resemble an 8. A #8 jack was 11 1/4" tall.

 

Pat 1886. And probably a #3 as said above.

 

You are correct it is a number 3 Thanks
(had to put my magnifiers on)

 

1935? Looks like 1886 to me!! Need to look closely!

 

Yes the very small ones are used by machinists; I have some about same size as yours but all steel. I've been waiting several years for the right job to come along where I would need to use them.

 

I found the patent US 336793A dated 2/23/1886 if anyone is interested.

 

Patent mentioned above

https://www.google.com/patents/US336793

 

And if I read correctly, he, Chapman, patented it not so much for a specific lifting jack use, but because he came up with a way to keep the screw sufficiently lubricated in all weather conditions????? NEAT!!! Providing I skimmed the article correctly...........