SUN-DIALS AND THEIR MOTTOES. 
9 
of the hour-circle and shows the time. It is necessary that the 
observer should know whether it is before or after noon when 
using this dial, or any of the others which I have mentioned; this 
being known, the dial not only shows the hour, hut the cross-bar 
points to the pole, the hour-circle lies parallel to the plane of the 
equator, and the outer ring points north and south. 
About the thirteenth century the mariners’ compass came into 
use in Europe, and was at once used in connection with sun-dials. 
Fig. 12.—Ivory Dial, 1561. Fig. 13.—Gilt Brass Dial by Y. S., 1570. 
The most common English form was a round metal box containing 
a compass with an ordinary horizontal dial above it, the gnomon 
being hinged so as to take less room; this type has remained un¬ 
altered to the present time, besides the one illustrated (Fig. 9, p. 8), 
