Paperweight or doctor's clocks are small spring-driven timepieces (average length about 4 1/4in. ). They resemble pillar clocks, being long and thin with a linear dial that shows the time on a graduated scale. The mechanism is of the pillar-clock variety with the spring and balance in a compartment at one end of the case. The spring is wound by drawing the hand to one end of the dial; as it unwinds the hand passes along the slot showing the time on the adjustable scale. Most such clocks are from the late period, after the 18th century, and have a balance cock in European style.