Replica of Williamsburg Greenwich Armillary Sphere Garden Decor. During the 18th century, a time of tremendous scientific interest, Britain and the colonies were fascinated with all kinds of tools and machines. The once-utilitarian armillary, a device designed to teach spherical astronomy, became more decorative by the end of the century. This one, which also functions as a sundial, is reminiscent of formal European examples found in Colonial Williamsburg's antiques collection. Virginia scholars such as George Wythe kept scientific instruments, possibly including armillaries, in their study.