Manuscript

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Detail from George Rapers manuscript

Observations by Lieut George Raper, R.N. 1787 to 1794
manuscript, ink on paper, stitched in original nonpareil paper wrappings (standard Admiralty stationery)
23.5 x 19 cm
Manuscript Collection MS9433/1

The Master of a ship was responsible for navigation and therefore the recording of solar and lunar observations to accurately plot a ship's latitude and longitude. In Raper's notebook we can see daily evidence of student navigation exercises that midshipmen on Royal Navy ships were expected to carry out during voyages. In particular, it documents the continued efforts to improve determination of longitude through constant experimentation with chronometers.

Each page is divided into columns and records standard nautical observations: date, time of watch, distances, longitude, and a record of errors of the chronometer on board.

The voyage of the First Fleet occurred at a time when chronometers, though still relatively new inventions, were becoming standard issue for the British Navy. Due to Captain Phillip's persistence the First Fleet was equipped with the K1 chronometer (named after its maker Kendall) which had been used by Cook on his second voyage. HMS Sirius was entrusted for most of the voyage with this precious instrument, a reliable timekeeper which remained unaltered by the motion of the ship.

Raper's manuscript records

... Capt. Phillip, who with Capt. Hunter or Mr Dawes were always to be present at the winding of it at noon, and it was ordered to be the duty of the Lieutenant who brought 12 o’clock to see it done, and the officer who relieved him was not to take charge of the deck ’til he was informed that it was done, the sentinel at the cabin door was also ordered to plant himself inside the cabin on hearing the bell ring at noon, and was not to go out to be relieved until he was told or saw that the timekeeper was wound up.
William Bradley

Raper's manuscript records the calculations of longitude by the lunar distance method, using sextants and tables, and then compares these with the calculations based on K1. His frequent notes about errors refer to the differing results—where there was a difference the chronometer was assumed to be the source of the error. Measurements were made at the same time on all four chronometers and averaged.

Records kept by midshipmen were not official records and were often retained by them, or their families, at the end of the voyage or, as in this case, used in subsequent voyages.

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