The full set of racks on which the thallium beam standard was installed at the Neuchâtel Observatory. Left: the beam tube in its vacuum tank. Centre: the hand-built interrogation electronics. Right: monitoring and counting — two oscilloscopes, the left one a Tektronix Type 502 dual-beam, and a Berkeley counter with its printer. It corresponds to the first configuration, in service between July 1962 and May 1963, which used a quartz frequency reference.