Abstract: An apparatus for conducting chemical assays features a coiled soft plastic tube as a reaction chamber. Along the length of the plastic tubing is a slit therein through which a needle-like member of a travelling dispenser injects samples to be analyzed. The injected samples may react with a reactant previously deposited in the interior of the plastic tube. The apparatus is applicable to carrying out radioimmunoassays.

Abstract: A ball throwing machine with oscillating capability is provided wherein the machine has a single shaft which rotates within a tube having bearings therein and wherein said tube is supported at only a single place near the center of the tube. The mechanism for oscillating the ball throwing machine is caused to rotate by the same mechanism that causes the throwing arm, which is directly connected to the shaft, to rotate. The oscillating mechanism drives a cam. A cam follower, which is connected to the throwing machine, is spring biased against the cam. As the cam rotates the cam follower and the throwing machine will be oscillated.

Abstract: A multi-mono FM transmission and reception system is provided whereby during a portion of the programming a four-channel music system can be broadcast and received and during another portion of the programming four discrete languages can be broadcast and separately received. An automatic switching system is provided so that with the proper equipment, one receives a four-channel music program during a musical transmission and a single selected voice channel during voice transmissions. Provision is made so that the main language of the country will be received on a mono receiver.

Abstract: A coin box mechanism is provided which can be easily set to be actuated by a combination of coins and wherein the combination can be readily changed without the use of tools. The coin box mechanism was particularly designed for use in conjunction with a newspaper rack, but it can be used in a large number of different applications.

Abstract: A muting circuit is provided for a phonograph record amplifier employing a semi-conductor cartridge wherein the cartridge has a shorting switch operative during the changing cycle wherein the amplifier associated with the cartridge is deactivated during the changing cycle of the pickup preventing transients in the output of the amplifier.

Abstract: A chopper for severed margins of multi-folded paper is provided wherein the margins are slit off the sheet and then chopped into small pieces which occupy a minimum amount of space and which present a simplified disposal problem.

Abstract: A simple carriage mechanism for a thermal printer or the like is provided wherein an escapement mechanism advances the printer from one character to the next.