I sometimes run across recipe that call for common crackers and
have had NO idea how large they were, which made it hard to
estimate that quantity of crumbs needed. I am flipping through a
book and just came across this, written by Ralph E. Flanders, the
then-Senator from Vermont: "The cracker called for in this recipe
is the old-fashioned 'common cracker' which in the old days filled
the cracker barrel at the country store. It goes under various
aliases such as St. Johnsbury cracker, Keene cracker, Montpelier
cracker, Hanover cracker, etc. It is the grandfather of the
regular oyster cracker, being however about three inches in diameter."

Source: The All American Cook Book: Favorite Recipes of Famous
Persons. Sponsored by American Legion Auxiliary Schuetz-Hermann
Unit 283, Lebanon, Illinois. Marceline, Missouri: Walsworth
Bros., 1954. Page 46.
--
Jean B., who feels compelled to set such things down for posterity