Abstract: The apparatus consists of at least one test-tube carrier defining seats for test tubes. The carrier is moved by oscillation or rotary motion about a horizontal axis under the influence of time control means. A structure which is vertically movable relative to the test tubes is fitted with individual means for the photometric observation of the data relating to each test tube and is controlled by time-control means. Processing and recording means collect data relating to the presence of each test tube, the presence of a sample, and the level of said sample, for each test tube seat.

Abstract: An electrical supervisory circuit arrangement, as for detecting faults such as yarn breakage in a circular knitting machine, comprises a number of channels each responsive to a particular type of fault signal in the machine. Each channel comprises a bistable transistor circuit which is switched in response to the particular fault condition to be detected and, when so switched, energises a warning light. In addition, all the bistable circuits are connected in common to an output transistor which is thus switched when any of the bistable circuits detects a fault. The output transistor controls two relays, one of which disconnects the forward-current supply to the machine and the other of which temporarily provides a reverse-current supply for braking the motor.