Enquire within upon everything by Robert Kemp Philp

63. Metagram,

a riddle in which the change of the initial letter produces a series of words of different meanings; from _meta_, implying change, and _gramma_, a letter. Thus: I cover your head; change my head, and I set you to sleep; change it again and again, and with every change comes a new idea.--Cap, Nap, Gap, Sap, Hap, Map, Lap, Pap, Rap, Tap. This kind of riddle is also known as word-capping. [GUNPOWDER MADE BY A MONK AT COLOGNE A.D.1330.]