Rectangular pasteboard frame in which slides two cards bearing names of months and a movable calendar. Brass eyelets help one position the cards within windows. Names of weekdays above columns of dates in calendar window. Table 1 correlates years with key letters. Table 2 correlates key letters to first day of each month. List of months with their number of days. Reference tables for 150 years, beginning in 1800 and ending in 1950.
Materiale
"B. G. BUTTON & CO., Publishers, Waterloo, Iowa. Copyright 1890".