Octant Information from the donor’s family, states that this octant was used at the Battle of Trafalgar onboard HMS Victory by Midshipman Jas Poad in 1805.   An octant is a portable navigation instrument.  It measures the angle between the horizon and a celestial body such as the sun, the moon, a planet or a star.  The navigator uses this information to calculate latitude at sea and, therefore, the ship’s position.   Octants were in general use from c.1750 - 1900.  The frame of this instrument occupies 1/8th of the circumference of a circle and so it became known as an octant (from the Latin ‘octo’).

IBC 0066