FARADAY AND HIS INFLUENCE ON OUR EVERYDAY LIFE. 211
to-day the housewife's drudgery disappears with the use of
domestic appliances. These devices involve and stimulate a
desire for a modicum of technical knowledge. In consequence
the Electrical Association for Women has grown from strength
to strength ; Faraday and Swan were unwitting founder-members.
Though Faraday made a dynamo and motor, many years
elapsed before electric machines of large size could be constructed.
The pioneer of the precise design of electrical machinery was the
late Dr. John Hopkinson, Professor of Electrical Engineering
in King's College, London. In the '80's he realised that
the fundamental characteristic of such machines was in
their magnetic circuit. He elucidated its laws and showed how
the electrical performance of the machine depended on it. He
forged the final link which binds electricity to magnetism, but
which withal allows us to drag electricity from magnetism.
Up to this point these disciples of Faraday had accomplished
their work in the laboratory and study. Hopkinson was a
practical engineer, but the man of affairs outstanding in the
commercial production of electrical machinery and apparatus
was the late Dr. S. Z. de Ferranti. Then existing steam engines
fulfilled none too well the requirements for driving electrical
generators. Ferranti developed engines of the type and speeds
appropriate, and built generators and transformers. In the
early '90's, when the rival claims of continuous versus alternating
currents were being hotly contested in words and in practice,
Ferranti boldly adopted alternating current at a pressure
absolutely alarming in those days, viz., 10,000 volts. No cable
maker was prepared to supply conductors insulated for such a
pressure ; Ferranti therefore himself designed the 10,000 volt
cables used to transmit power from Deptford to London. These
pioneer extra-high-tension cables did their work for thirty-five
years. Ferranti was indeed a most versatile man.
In this connection it is interesting to note that Faraday
investigated the properties of dielectrics and laid down principles
governing their behaviour. He realised that the insulation
played a part as important as the conductor in conveying
electrical energy, quite apart from the prevention of leakage of
electricity. The fruits of this work spring from our soil in the
form of the Central Electricity Board's grid.