horologer (n.)

late 14c., "clock-maker," via Latin from Greek hōrologe "clock, timepiece, instrument for measuring the hours of a day," from hōrologos "telling the hour," from hōra "hour" (see hour) on model of astrologer, etc. Hence also obsolete English horologe "timepiece, sundial, hourglass, clock, cock" (late 14c.) and the old expression the devil in the horologe for "mischief in an orderly system" (17c.).