A terrella tiled from an original oil portrait

from an original oil portrait by Jervas at the Royal Society

The Poor Man's Friend'

with hands of a sensitive refinement in painting worthy of the most respectful study"

but his father was a Spanish Jew

Obelisk at Monken Hadley

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