| The apparatus manufactured by Daniel Davis,
Jr. of Boston in the dozen years before 1850 demonstrate the principles
of electro-magnetism in particularly elegant fashion. Few pieces of apparatus
available today can match its clarity in illustrating the principles of
the motor, the generator and the induction coil. His book and catalogue,
the Manual of Magnetism and the many surviving pieces of his apparatus
give a good picture of the electrical knowledge in the middle of the nineteenth
century. |