a mathematical instrument, used to work questions in gauging, measuring, and the like, without the use of compasses, merely by sliding the parts of the instrument one past another, the lines and divisions of which give the answer by inspection. This instrument is variously contrived and applied by different authors, particularly Everard, Coggeshall, Gunter, Hunt, and Partridge; but the most common and useful are those of Everard and Coggeshall.