Abstract: A clock with a twenty four hour display includes a minute hand, a second hand, a minute scale, a date display, and an hour scale on a first conchoid. The first conchoid includes an outer loop for the hours of the day from 6-18 hours and an inner loop for the hours of the day from 18-6. A crossing point of the inner and outer loops is established at the hours of 6 and 18. To achieve unambiguous indication, the hour hand is made variable in length. In a second conchoid offset by a constant amount radially inwards with respect to the first conchoid, which for instance is milled in the form of a groove in the dial, a guiding element is moved azimuthally through the inner part of the hour hand, which receives an overlay of radial movement owing to the shape of the second conchoid. The second conchoid and the guiding element may be covered by a disc joined to the inner part of the hour hand and turning with it.