I do not know if this has been made known before, but a new book on Nelson Barbour is available at:
http://www.lulu.com/product/paperback/nelson-barbour-the-millenniums-forgotten-prophet/5424152
The number of people at that time who were setting dates for Christ's imminent return certainly put today's date-setters into context. When people fail to heed history, they repeat its mistakes.
Doug