Sentence:  The types are of the usual thickness and height. In the centre of each type, in the front, is a deep <WSD>nick</WSD> of a dovetail shape, which fits upon a metal edge, so that the type cannot be displaced. But of 111 letters which are required in the fount, each letter has two, three, or four other <WSD>nicks</WSD> cut at right angles, the <WSD>nicks</WSD> of no one letter being the same as another. 
Meaning of the word marked with <WSD> tags:  A notch cut crosswise in the shank of a type, to assist a compositor in placing it properly in the stick, and in distribution.