A terrella expensive 'Wittington's Ghost'

'Wittington's Ghost'

Plan of the City of London and surrounding area showing fortifications erected during the English Civil War

Matthew Wood

She set a women's record for the 12-hour time-trial which exceeded the men's record for two years

A terrella expensive 'Wittington's Ghost'A terrella ('little earth') is a sphere made of a magnetized substance, used to simulate the magnetic field of the earth. In the 16th century the English physician William Gilbert used a terrella made out of lodestone (a naturally occurring magnetized mineral) to demonstrate that the earth is magnetic, and to explain how mariner's compasses work. 17th century