Sward Hardness Rocker

[pantrwrstl]

Picked this up last night... I kind of know what it is, but can't find very much info on them. I see newer ones go for a decent amount of money, but again I couldnt find this particular one anywhere. The only thing I found was half an article on google books to which it cuts out before the bigger details, and an ad from a news paper from 1938 talking about it, but the site wouldnt let me look at the full size ad without paying for a membership. Sooo if anyone knows about it, especially a value I could possible place on it, I would be appreciative, thanks!


the liquid in both vials are all orange, I think the green is from the metal behind it

[frogpatch]

Here is a spec sheet if that helps
http://www.sheeninstruments.com/datasheets/har.pdf