Each head is graduated into Ioo equal parts on the drums u and v, so that, by estimation, the reading can easily be carried to ivioDth of a revolution.
D is the drum-head which gives the fraction of a revolution, d that which gives the whole number of revolutions, I is the index or pointer at which both drums are read.
The divisions of both drums are conveniently read, simultaneously, by the lens e; at night the lamp which illuminates the webs and the position-circle also illuminates the drum-heads (see on illumination p. 385).
In a type built with vertical sections each division is complete in itself, and is not directly connected with the next section, but communicates with flow and return drums. A defective section may thus be left in position and stopped off by means of plugs from the drums until it is convenient to fit a new one in its place.
Accounts differ as to his conduct at the execution, some stating that he ordered a roll of drums to drown the king's voice.
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