Thank you for the email and congratulations on your find. The planchette you purchased is definitely unique!
Our research into early planchette production indicates that Selchow and Righter were the first American company to manufacture the devices for commercial purposes. There were, of course, planchettes made long before that...Ancient Chinese and Native American Indians had similar devices.
The planchette you own is likely one of the first to be produced commercially in the United States. It was probably produced in the late 1860s by Selchow and Righter at their New York factory. When the company first marketed and advertised its product, it was advertised as a "scientific instrument." Its initial use was to detect involuntary motion, (often called the idiomotor effect) in humans. Basically, the planchette was first advertised as a tool which could tap into the human subconcious.
With the growth of the Spiritualism movement in the late 1860s, however, people began to use the planchette to communicate with deceased spirits. The planchette you read about on our website, the "Mystic of Mystics," was the first one commercially advertised for a Spiritualist audience.
Your planchette looks like its in great shape! Congratulations and hope this helps. PS - We would be interested in writing an article about your planchette if you were willing to allow us to use your images. No worries if you don't feel like sharing, just wanted to offer!