He discovered that magnetic declination – the angle of dip of a compass needle – is not constant but changes over time.
[3] He was the son of the physician Henry Gellibrand (1568–1615)[4] and Mary Faversham.
[5] Samuel Gellibrand became a prominent seventeenth-century London bookseller.
[7] The mathematical tables of Henry Briggs, consisting of logarithms of trigonometric functions, were published by Gellibrand in 1633 as Trigonometria Britannica.
He was buried in St Peter le Poer, a London church that was demolished in 1907.