A terrella tiled from an original oil portrait

from an original oil portrait by Jervas at the Royal Society

sailing from Plymouth to New York City in 40 days

Obelisk at Monken Hadley

Map with geological information shown in colours and a vertical scale in the bottom margin

but his father was a Spanish Jew

A terrella tiled from an original oil portraitA 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