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My name is Jessica Helfand and I am on the faculty in Graphic Design at Yale School of Art. I am currently researching and writing a book on volvelles (to be published next spring by Princeton Architectural Press) and I am looking for any information on a series of map wheels I have come across, most of which were published in the 1930s by the Rossig Educational Chart Company (NY) and the Chart of Knowledge Company of America (Boston.) I am attaching a sample image and have, at present, more than twenty of these map wheels showing US and European Geography.

I hope also to include a sizeable section on 19th and early 20th-century Planispheres, including those manufactured by Philips, Miller, Whittaker, Whitall and Barritt-Serviss, among others. Because the emphasis (and my expertise) is on graphic design, I am most interested in planispheres that include typography and offer unusual examples of information design (arguably, very early "interactive" information design.) I am including a representative image of the Barritt-Serviss Star and Planet Finder from 1906.

Any information on the history, use or manufacture of these wheels would be greatly appreciated. Thank you.