Varley's lightning protector for telegraph lines, 1861.
© Science Museum / Science & Society Picture Library
Pole-suspended bare-wire telegraph lines are extremely vulnerable to lightning, which can damage the very delicate electrical instruments and possibly injure the operators. Lightning arresters provide a means of diverting lightning strokes to earth, and have been produced in many different designs since the beginnings of electric telegraphy. This one was designed by pioneering electrical engineer Cromwell Varley.