Abstract: A thermostatic ventilator operator has a thermostatic actuator consisting of a pair of tubes telescoped together with a plurality of thermally responsive power elements arranged coaxially therein. An operating lever is pivoted on a mounting bracket. The thermostatic actuator is pivotally connected to the mounting bracket and to the operating lever with one of the pivots being slidable in a direction normal to its axis. A pair of extension springs bias the slidable pivot in one direction.

Abstract: A cold frame for providing an environment conducive to the growing of plants having walls and a flexible, light-transmitting cover member which is flexed to form a ventilation opening. The cover member is flexed manually or by means responsive to the temperature of the interior of the cold frame.