When Matthew Flinders set out in 1801 to circumnavigate Australia, he took with him a collection of five chronometers. The only one to survive the journey was this one. It was made in London by Thomas Earnshaw in early 1801. The escapement and compensating balance wheel which were invented by Earnshaw are incorporated into this chronometer and reflect his skill and precision in workmanship. Flinders expressed his enthusiasm for E520 in his book 'A Voyage to Terra Australis' where he referred to it as "this excellent timekeeper".
Like three other timekeepers on the investigator, the E520 was a box chronometer. That is, it was mounted in a wooden box fitted with gimbals, to compensate for the movement of the ship. During the voyage the chronometers were removed from the ship only to be checked. An observatory tent was erected at selected points along the coast where the timekeepers were checked against a regulator clock to determine whether they gained or lost time each day. There were also regular checks of the chronometer rates by astronomical observation on board ship.
The E520 was with Flinders when, on his return passage to England, he was taken prisoner-of-war by the French in Mauritius. In 1805 Captain Aken, the master of the 'Investigator' who had been travelling with Flinders, was released by the French and allowed to return to England. He arrived there with the chronometer in December 1805, and the Astronomer Royal, Neville Maskelyne, reported to the Board of Longitude on December 12, that E520 had been delivered to the Greenwich Observatory.
No more was heard of E520 until 1937 when the records of the then Sydney Technical Museum show that it was purchased from Mr. J. Nisbet of Double Bay.
At that time however, it was not recognised as the chronometer carried by Flinders. This situation remained until 1976, when this author identified it by its serial number as a chronometer from the 'Investigator'. This would normally have been sufficient identification but a search of British Admiralty records indicated that they had been offered and had declined the purchase of an Earnshaw chronometer no. 520 in 1943.
Subsequent research in England revealed that the owners of this chronometer had since died and the family were unaware of its existence. To further complicate matters the Admiralty had destroyed most of the records pertaining to the chronometer.
However, there was what appeared to be a second serial number engraved on the back plate of the Museum's chronometer which could possibly provide additional proof of its authenticity. A further search at the National Maritime Museum in London revealed that all known Earnshaw chronometers made between 1790 and 1810 carried a second number. In our case the number is 2865. A study of a graph prepared by Mr. Christopher Wood, of Edinburgh, comparing the first and second serial numbers, together with a check of other Earnshaw chronometers leaves no doubt that this Earnshaw chronometer was the one carried by Matthew Flinders on the 'Investigator'. The most probable explanation of the chronometer offered to the Admiralty in 1943 was that due to repairs to the dial the number was indistinct and was misread by the recording clerk.
But what of Mr. N. J. Nisbet, who once owned E520? At first all attempts to trace him failed. Then in 1979, with the valuable assistance of Caroline Jones of ABC Radio in Sydney, the family of Mr. Norman John Nisbet was located. Unfortunately, Mr. Nisbet died in 1943 and little is now known of E520's connection with his family. Mr. Nisbet was, however, a collector of clocks and watches and may have acquired the chronometer during a visit to England.
Whatever the history of E520 from 1805 to 1937 it is extremely fortunate that this historic old timekeeper which played so important a part in our early history, found its way back to Australia.
By Thomas Tooth, 1981
Thomas Tooth, transcript from 'The Earnshaw Chronometer' a monograph originally published by the Powerhouse Museum of Applied Arts and Sciences, 1981