If the 'Principle of Relativity' in an extreme sense establishes itself, it seems as if even Time would become discontinuous and be supplied in atoms, as money is doled out in pence or centimes instead of continuously;-in which case our customary existence will turn out to be no more really continuous than the events on a kinematograph screen;-while that great agent of continuity, the Ether of Space, will be relegated to the museum of historical curiosities.