Thunder House demonstration model made by George Adams, Fleet Street, London, 1771-1796.

This instrument was made by George Adams, instrument maker to King George III, to demonstrate the action of lightning conductors. An electric spark jumped between the two balls above the house, imitating a lightning strike. If the lightning conductor was in place the charge was earthed safely. However, a small piece of the conductor could be removed and replaced in the wrong position. If the house was struck again this piece would jump out, representing damage. James Ferguson, a lectuer on natural philosophy in the period, noted that this type of demonstration model was invented by Dr Lind in Edinburgh in order to test Benjamin Franklin's theories of lightning conductors.