Abstract: A hand trowel device for particular use in roofing and like constructions is specially provided with an integral heating means. The heating means is adapted to continuously maintain the trowel blade at a temperature sufficient to plasticize or render flowable, preferably under applied pressure, the roofing compound or roofing cement employed. The roofing compound to be plasticized may be pre-impregnated in or otherwise integrated with the roofing sheet (or "felt") material being used in the roof covering or it may be separately provided for the purpose of independently sealing and waterproofing the roof covering material, particularly lapped edge or flashed edge portions of sheet roof covering material. Also, since it is a hand trowel, the trowel device is provided with a convenient hand gripping portion to facilitate lifting, carrying and manipulating the trowel during use and, in addition, an attached safety stand for supporting the hot or heated trowel in a rest position elevated above the roof surface.

Abstract: A device for photoelectrically starting and stopping the operation of a bunsen burner in response to the shadow of an operator's hand holding an object to be heated includes a solenoid valve in a line supplying gas to the burner and electronic control circuitry having secondary and primary photoelectric cells arranged in a differential response circuit. Changes in the intensity of the ambient light are cancelled by the differential response circuit, while a hand shadow, which affects only the primary cell, triggers the solenoid valve, via a gate circuit and solenoid switch.

Abstract: A device for electrically starting and stopping the operation of a gas burner in response to the shadow of the user's hand holding an object to be heated, the device including a solenoid valve in the gas line and a dimmer circuit with a directional photoelectric sensor, a switching amplifier, and a valve relay controlling the solenoid valve. The dimmer circuit can be bypassed for continuous operation by means of a selector switch.