This instrument is extensively inscribed with mottoes and instructions on the use of the dial itself.The inscriptions on this instrument read 'the critic must not despise anything unless he could make it better' and also 'I, called compass, show the way through all countries by day and by night, if one knows how to use me' stressing the usefulness and universality of the dial.
It also has an unusual combination of two basic elements in diptych dials, a lunar volvelle and a wind rose.
