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