From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Description of the Cambridge Instrument Co's Recording Thermometer No. 27591.
| Identifier | ExFiles\Box 33\4\ Scan232 | |
| Date | 7th February 1927 | |
| EFC. AC.80. X/782 7.2.27. CAMBRIDGE INSTRUMENT CO'S RECORDING THERMOMETER NO. 27591. This instrument incorporates a clock mechanism with escapement gear, which drives a recording drum at either one revolution in 25 hours or one in 2 hours 5 mins. as desired. A suspended coil galvanometer is arranged with its needle capable of being made to depress an inked thread on to the drum, thus recording a dot. Terminals are provided for connecting it to thermo-couples situated at the points where temperatures are to be measured. Two threads are employed of different colours and at intervals of one minute the escapement clock releases another clockwork mechanism fitted with an air brake for limiting the speed, which depresses the galvanometer needle, releases it, throws over a rocking frame carrying pulleys on which the threads are mounted, and tilts a change-over switch containing a mercury globule contactor. The motion of the thread frame brings alternate colours under the galvanometer needle at succeeding operations, and similarly the mercury contactor connects the galvanometer to alternate thermo-couples for which terminals are provided. One of the thread pulleys (with grooves for both threads) is advanced by a small increment at every alternate operation of the marker (i.e. once every two minutes). Thus a simultaneous record of two temperatures is obtained as a series of dots of distinctive colours for each. EFC/F.J. Allen. | ||