William O. Douglas

“ The point is that in Mead's combination the effective operation of the thermostat was placed under the sole control of the temperature of the working resistance. We agree, however, with the court below that any such difference was merely one of detail of design on which Mead's invention cannot rest. In any case, it is the temperature created in the vicinity of the thermostat that is effective. The manner in which it is transmitted to the thermostat does not rise to the dignity of a patentable device. ”

“ In a device of the class described, a removable heating member having an electrical heating unit, a socket for receiving and holding said heating member, electrical current supply terminals, means for moving said heating member to a position for establishing an energizing circuit to said heating unit, and means responsive to the temperature of said heating unit for interrupting said energizing circuit.↑ Some of these are reviewed in Casco Products Corp. ”

“ To mention only the more important, Mead showed a rotatable socket which is turned by manually rotating the plug when placed in the socket, so as to close the heating circuit. A laterally extending pin projecting from the side of the plug in the Mead structure engages with a spring latch outside the socket to hold the plug and socket in the circuit closing position to which they have been rotated until the latch is released by the thermostatic control, thus permitting the plug and the socket, which is activated by a spring, to rotate back to the open circuit position. ”

“ And so the question is whether it was invention for one skilled in the art and familiar with Morris and Copeland, and with the extensive use of the automatic thermostatic control of an electric heating circuit, to apply the Copeland automatic circuit to the Morris removable heating unit in substitution for a circuit manually controlled. ”

“ Strict application of that test is necessary lest in the constant demand for new appliances the heavy hand of tribute be laid on each slight technological advance in an art. The consequences of the alternative course were forcefully pointed out by Mr. ”