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[Page 18]
the distant Points in one with the nearest, as they open out or shut in by which not only the Error of the Course will be Corrected but the Bearing of the Coast in detail will be obtained also.
It is expected that the Variation of the Compass either by Azimuth or Amplitude, or both should be regularly taken each Morning & Evening; which will furnish a mean of the Variation from Time to Time; & such Variation is of Course to be allowed in protracting the Course & Bearings
It may be best to take a Mean between the Evenings & next Mornings Variation; as there may be a central Error in ye Compass
When an Observation of Latitude is taken, the part of the the Coast, that bears true East or West, is to be particularly noted & described in General Terms. If no Land, remarkable enough to be recognised, appears in those very Points, the most remarkable part of the Coast near them must be set & described. The same kind of Process must be followed, respecting Lands in the North or South when an Observation of Longitude is taken
When by a failure of an Observation of Latitude the series of Triangles from the last Place of Observation, require Correction in point of Scale, it becomes necessary to have recourse to a Base measured by the velocity of Sound. on such an Occasion the Consort Vessel after a proper Explanation concerning the Objects that are meant to be determined by the Base, may separate to a proper distance & firing a Gun by signal agreed on, the proper Angles may be taken at the same Instant on board the the two Vessels by the Hadleys Quadrant; & also lines of Bearings between the two Vessels, & to one of the distant Objects. Perhaps, it may be prudent to fire a 2nd Gun after an Interval previously agreed on, & to