This is an early English "Scientific" Sundial, with exactly calculated, unequal hour angles. Early sundials of this type are rare. It was excavated at Scadbury Manor, home of the Walsingham family ...
Hayes, having borrowed a book from a personal or a subscription library in Philadelphia, sat down with a set of drawing instruments and followed the instructions for drawing a sundial on a card.
This is a horizontal compass sundial, made of gilded silver. It is of 'Butterfield' type, named after English manufacturer Michael Butterfield, who popularised the adjustable bird gnomon.
Julien Coyne invented a digital sundial. Sundials usually cast a line or triangle to indicate the hour. This one is designed so that when light passes through, it displays the shapes of numbers.