Hour lamp – time is told as the oil burns down.
Hour candle – time is told as the wax burns down by way of an hour scale printed on the side of the candle.
Sundial – tells solar time. A shadow of the gnomon (pointy-up bit) is cast around a rudimentary clock face, telling solar time. The part of the Gnomon that casts the shadow is known as the style.
Hour glass/sand timer – Sand trickles through a glass container with a pinched centre at a known rate. When all the sand has passed from one side to the other an hour (or another set time) has passed.
Clepsydra – an earthenware pot with holes in, filled with water. Time is told by the amount of water left in the pot.
Gnomon – tells solar time as the sun casts a shadow from a stick stuck in the ground. Time is told from the length and position of the shadow. For this reason, a gnomon records the real/true solar day and not the mean solar day as its reading is denoted by the sun’s position in the sky. Gnomon is derived from Greek and means indicator.
The study of Gnomons is called Gnomonics, and a studier of Gnomonics is called a Gnomonist.