An apparatus and method for aerial chemical trimming of vegetation, the apparatus including an elongated boom suspended from an aircraft, a plurality of nozzles aligned vertically along one side of the boom, and a reservoir and pump coupled to a lower end of the boom for supplying an herbicide through the boom to the plurality of nozzles. A shape of topography at the detected designated position of the topographic object and in a vicinity thereof, into a shape whose height is gradually changed, depending on a distance from the designated position. The self-purging preservation apparatus is placed in an insulated transport container having a cooling medium. The tracking mechanism may be comprised of two trackball assemblies. A cascode bias voltage of a folded cascode circuit in the CMOS operational amplifier circuit is modulated by a current at an input differential stage, thereby enabling operation with low noise, with low current consumption, and with stability. The shaft can be fastened and affixed to the shaft hole without tilt.