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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.
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... 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 resultswhere
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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