The deep V at the top of each matrix is actually a key to allow the matrix to drop off the distributor bar back into its proper channel in the Linotype magazine. The projections or "ears" at the four corners are to keep the matrix straight in the several machined channels it has to follow on its round to and from casting. The letter of each matrix is cut in reverse in the side. The slug is a solid line of type, ridged on its underside by the shape of the machine's moulds.
Courtesy: The Author and National Film Board of Canada
