Regulators such as this were designed to be portable. They were intended for both astronomical and survey purposes; hence the bob on the present clock is calibrated for both mean and sidereal time and it can be quickly adjusted so that the clock can be rated according to either system. For ease of transport the cases have handles and the movement, with its heavy bracket, can be placed on the wall independently of the case. A similar clock, No. 3300, is illustrated in Tardy, French Clocks, Vol. II, Paris, 1981, p. 343 and another, No. 705, with solid front panel, is illustrated in Roberts p. 63. For Breguet see also lots 98, 99 and 102.