... in the darkest night that is ... Briggs, Blundeville, Wright, and the misconception of finding latitude

Abstract

Dedicated to the memory of Jacqueline Stedall

When William Gilbert published his monumental work De magnete in 1600 natural philosophy in early modern England was born. In his work Gilbert included a theory of magnetic inclination, called dip, and devised an instrument to find latitude from dip. Here we describe and analyse this theory which was turned into mathematics by Henry Briggs.

Notes

¹ I refer to the English translation (Gilbert 1958), translated by Sylvanus P Thompson.

² The New Attractive, London, 1581. Even before Norman the dip was reported by the German astronomer and instrument maker Georg Hartmann from Nuremberg in a letter to the Duke Albrecht of Prussia from 4 March 1544, see Balmer 1965, 290–292.

³ A word of warning seems appropriate here: in Gilbert's time many authors—including Gilbert—used the word declination for the inclicnation.