4. First case study – the subdivision of the light - HM Treasury

F05 Ch4 Subdivision of the light.doc
05/04/2006 19:34:00
Technological roulette – a multi-disciplinary study of the dynamics of innovation in electrical, electronic
and communications engineering.
4. First case study – the subdivision of the light
Edison took three steps to facilitate the changeover for potential customers. He first
obtained an undertaking from the New York Board of Fire Underwriters that insurance
rates would be unaffected if a Board inspector examined the wiring before connection was
made to the street main. Secondly, the Illuminating company made it known every
household in the district that the company would bear the cost of making the connection
between the street main and the house wiring and the expense incurred in wiring the
building until the consumer had decided whether or not he wanted the electric light
permanently. Any consumer who, after a period of trial, decided not to continue with the
Edison light would not be charged for the wiring or the connection. Finally, in order to
prove the reliability of the system, there was to be a three-month moratorium after
connection before charging commenced.
The output of the Edison lamp was 16-candle power, matching that of the ordinary
gas jet. The Illuminating Company billed on a monthly basis, like the gas companies and
the lamps were usually referred to as burners. The customer was billed for light-hours
consumed instead of for electric energy to avoid introducing terminology with which the
consumer would not be familiar.
Some years later, when electric lighting was well established, it had a reciprocal
influence on the gas-distribution system as gas engineers adopted the electric feeder-main
principle in order to equalise gas pressure at the jets without incurring the expense of
larger pipes.
4.5 Sources based on refractory oxides
4.5.1 Limelight
In June 1824, at the instigation of
a Select Committee of the House of
Commons, a survey of Ireland was
undertaken by the Royal Engineers. A
high-intensity source of illumination
was required to pinpoint observation
Rees 1978
Fig. 4.11 Oxy-hydrogen limelight lamp (1830)
posts and, after a series of experiments, Lieutenant Thomas Drummond built a device in
which a ball of quicklime 3 /8 inch in diameter was heated in a stream of oxygen directed
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