The difference between horizontal sundial and equatorial sundial

Installation method and timing principle.

1. Installation method: When installing the horizontal sundial, the pointer is placed horizontally, facing due south or north. The pointer projects the position of the sun on the horizontal plane, and the installation axis of the equatorial sundial is parallel to the earth's rotation axis. The disk of the sundial is placed vertically, and the shadow of the pointer pointing to the sun moves on the disk.

2. Timing principle: the timing principle of horizontal sundial is to measure time by the position of sunlight projected on the horizontal plane, and the timing principle of equatorial sundial is to measure time by the projection of sunlight on the disk.