antique adjustable chair

I spotted this chair while shopping in a small town in northern Maine. The adjustable seat height is what first caught my attention as I have never seen the design before. Upon closer inspection I noted that the back rest is also adjustable both vertically and horizontally. The back rest itself is also on a pivot to maintain contact with your back. The owner accepted an offer of $25. I showed it to an 87 year old friend of mine who is fine cabinet maker and craftsman of over 70 years. He stated (while excitedly inspecting and adjusting the chair) that he had only ever seen 1 before and then only in a photo. He said it was in "wonderfull" condition and would gladly take it off my hands for far more than I paid if it was for sale. Sadly he could not tell me anything as far as where, when, who or why about the chairs design and history. I would be very gratefull for any and all information anyone may have concerning this odd little chair.