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The Quartz Clocks at Herstmonceux

Page under construction

The early 1950s saw considerable developments in both electronics and time keeping technology. The first transistors were developed in America in 1947 and the world's first caesium (atomic) clock was built by Essen and Parry at the National Physical Laboratory in west London in 1955. In light of this, final decisions on the detailed layout of the Time Department's accomodation and the equipment to be installed there were delayed for as long as possible in order that the adopted designs would be as adaptable and future proofed as possible. As well as providing individual 'cellars' for the quartz clocks, provision was made for housing the atomic clocks of the future, which according to Geoge Wilkins, included a caesium fountain clock, which at that time was little more than a germ of an idea.

The Time Department was the last to move into the Observatory's new home at Herstmonceux. It moved into the newly completed West Buidling in 1957. Prior to the building being handed over, three quartz clocks were set going in the cellars in early 1957. Designated H11, H12, and H13, they incorprated the ring-crystals previously used at Abinger in clocks B6, G4, and B5, respectively. Over time, twelve quartz clocks were installed in total, the first nine incorporating crystals from Abinger and the last three being commercial models by Sulzer. The last of the standards designed and built by the RGO, was taken out of service in 1967.

The Quartz Clocks installed at Abinger and Greenwich from mid-1944 onwards

 

The West Building where the clocks were housed

 

Summary table of the quartz clocks installed at Herstmonceux

H11-H19 all used ring crystals that had previously been used at Abinger and were cut to oscillate at 100 Kc/s. The Sulzers were solid state instruments and were designed to oscillate much faster at 2.5 Mc/s.

	Name	Type	Maker	Crystal	Date	Comment
	H11	Ring	GPO/RGO	40	1957 Feb	Contained Crystal from B6
	H12	Ring	GPO/RGO	39	1957 Feb	Contained Crystal from G4
	H13*	Ring	GPO/RGO	35	1957 Feb	Contained Crystal from B5
	H14(1)**	Ring	GPO/RGO	69	1957	Contained Crystal from E6
	H14(2)**	Ring	GPO/RGO	30	1957	Contained Crystal from C5
	H15	Ring	GPO/RGO	47	1957	Contained Crystal from D5
	H16	Ring	GPO/RGO	21	1957 Jul	Contained Crystal from E6
	H17	Ring	GPO/RGO	17	1957	Contained Crystal from E5
	H18	Ring	GPO/RGO	?	1958/59	Contained Crystal from C6
	H19	Ring	GPO/RGO	69	1961 Sep	Crystal from H14(1)
	H20	Lenticular AT-cut	Sulzer		1964 Mar
	H21	Lenticular AT-cut	Sulzer		1964 Mar
	H22	Lenticular AT-cut	Sulzer		1965 Nov	H22 identifier subject to confrmation

* Taken out of service in 1961 and its its ring-crystal and oven used in an experimental, prototype, transistorized oscillator
**Brackets were not used in the Observatory's documentation, but are used here to indicate when a clock was given a new crystal but its name was unchanged. H14 was originally built using the crystal from E6. The crystal  developed a fault in October 1957 and was replaced by the crystal from C5 in November 1957

 

Description of the clock from Royal Greenwich Observatory Bulletins, Number 8

Published in 1959, Royal Greenwich Observatory Bulletins, Number 8 covered the operation of the Time Service from October–December 1957. It gave the following details about the configuration of clocks H11–H17 at that particular time.

‘All the quartz clocks at the royal Greenwich Observatory employ Essen Ring crystals transferred from Abinger during 1956–1957. The oscillators are installed in individual cellers in the sub-basement (one oscillator to each cellar) and each is supplied from an independent battery system. The dividers and associated equipment installed in the clock room on the basement floor. …

Each oscillator operates at a nominal frequency of 100 kc/s and a buffer amplifier provides 4 mutually independent outputs. One output circuit from each oscillator is connected to the rotary beat counters which are read visually three times a day and checked by automatic simultaneous photography at 09 57 30 U.T. daily.

Other output circuits from selected oscillators are connected to regenerative dividers which reduced the frequency 1 kc/s and then through adjustable phase transformers to dekatron dividers providing output pulses at second intervals and half minute identification signals. In order to provide sidereal seconds intervals and sidereal frequencies for use within the observatory, the one kilocycle per mean-time second frequencies are applied to continuously phased transformers which are driven by phonic motors as a speed corresponding to the difference between mean and sidereal time. The output frequency of 1 kilocycle per sidereal second may be employed directly or through dekatron dividers to give sidereal seconds pulses. Phonic Motors driven by a 1 kc/s current and fitted with mechanical contacts are also available.

Clock comparisons are based, whenever possible, on the indications of the rotary beat-counters. In all comparisons between clocks and radio time signals and for the control of all radio time signals originating at the Royal Greenwich Observatory the precise second pulses derived from the dekatron dividers are employed in preference to the less accurate signals furnished by mechanical context, with the exception of the control of the rhythmic series which is scheduled to cease 1957 [1958] June 30.’

The 1954 Report of the Astronomer Royal (which covered the twelve months ending 30 April 1954) states that ‘The beat counter dials are photographed automatically at the same time each day.’ In the 1962 Report however it was stated that: ‘The beat-counters which monitor the various clocks are automatically photographed twice a day.’ Both statements are at variance with what was said in the Bulletin. It is not clear when the practice of photographing the beat counters started nor is it clear why the time of 09 57 30 U.T. was chosen.

 

The clock cellars

At Abinger, the quartz oscillators had been mounted on brick piers with the maintaining amplifier and temperature control circuit directly above it. At Herstmonceux, it was decided to try and give extra protection against vibrations by mounting the oscillators in spring mounted concrete cradles.

 

Location of the Clock Cellars

 

The Control Room and the Phonic Motor Room

At Abinger, the radio reception and comparison equipment, the time signal equipment, and the quartz clock divider stages and beat counters were arranged in that order in one long unit made up of 25 standard sized racks with the phonic motors on a table on the opposite side of the room.

At Herstmonceux, the equipment was spread across two separate rooms, the Control Room and the Phonic Motor Room. The control room contained the radio reception and comparison equipment on the window (west) side and the time signal equipment and beat counters on the right. The phonic motor room contained two racks of equipment - one of full height on the window (west) side and one at waist height with the (five) phonic motors for sending out time signals on top on the other side.

The two rooms at Herstmonceux were completly redesigned in 1970 in order to incorporate recent developments in electronic techniques. All the photographs on this page predate this event.

 

Further reading

 

Notes

1955 report: An increasing proportion of the Time Department’s work has been devoted to the formulation of detailed plans of the new installation in the West Building at Heretmonceux. Final decisions on these matters have been delayed as long as possible in order that the adopted designs should incorporate the most up-to-date techniques. The whole pattern of the Department’s work is at present in a state of rapid change, which makes it extremely difficult to foresee and cater for the probable needs of a few years hence. The situation is further complicated by the special responsibilities which will fall upon the Time Department during the Inter­national Geophysical Year.

1957 Report: Three quartz clocks were set up in cellars in the new West Building at Herstmonceux early in 1957 and are now running. These have been designated H.11, H.12, and H.13, and employ the ring-crystals previously at Abinger in clocks B.6, G.4, and B.5, respectively.

1958 Report: three additional operation clocks set going since the last report are:- H.14, H.15, H.16, incorporating the ring crystals used in the Abinger clocks E6, D5 and D6 respectively. The crystal in clock H.14 developed a fault, and was replaced by that formerly used in Abinger clock C5.

1959 Report: Two more quartz clocks have been installed during the year, H17 and H18, incorporating the ring crystals used in the Abinger clocks, E5 and C6 respectively.

1962 Report: Ring crystal No. 69 was sent to the G. P. O. for investigation; after a complete renovation it was installed as oscillator H19 in 1961 September. Oscillator H13 was taken out of service in 1961 September and its ring - crystal and oven are being used in an experimental, prototype, transistorized oscillator.

1967 Report: The last [H12?] and best of the quartz crystal standards designed and built by the RGO, which incorporated an Essen ring crystal was taken out of service in 1967 May after an oven failure, having been in use from 1954.