CBOT hand signal instructional sign from old visitors gallery

This piece was obtained by a former CBOT member who received it when the old visitor's gallery was torn down. I'm not sure when the quoting of grains went from 1/8th of a cent to 1/4ths of a cent so please inform the blog by emailing tradingpithistory 'at' gmail.com or writing in the comment box if you know so. Thanks!