First Mercury Street Lighting Installation

On the 22^nd June 1932, history was made when the worlds first mercury vapour street lighting installation was switched on.  The light source was the Osira 400W MA lamp which had been developed by The General Electric Company of England that year, and the location was East Lane in London, just outside the Hirst Research Laboratories and Wembley lamp works of that company.  The lanterns were simple protective globes of clear glass which afforded no optical control, but nevertheless the effect was particularly striking.  The new lamps lit the street with an efficacy 2.5 times greater than the 1000-watt tungsten lamps they replaced, bathing the road in a daylight colour light with spectacular intensity.

Not surprisingly the installation sparked considerable interest not just within the Corporation of London, but throughout the whole country and indeed internationally as well.  City engineers travelled from all over the world to witness the striking brilliancy with which these innovative new lamps were lighting the road.

Figure 21 - The Watford Road Installation

This first installation was merely an experimental trial for the GEC, and within a few months it became clear that it should be conducted more scientifically, with new lanterns developed specifically to work with the tall column of light created by the Osira lamps, which had to be burned vertically.  On the 2nd March 1933 an improved installation was put into service on the adjacent Watford Road (Figure 21).

Fig. 21 - The GEC Watford Road Lantern

Forty-six units were employed over a one-mile stretch of the road, and a new unit of highly original appearance, the Watford Road lantern, was designed for the Osira lamps.  The lantern is shown both by day and by night in Figure 21.  It was noted straight away that owing to the fact that the light was generated from a tall vertical column of luminous vapour, rather than the tiny compact source of filament lamps, that the arc itself was conducive to soft shadows and good diffusion.  The overall level of visibility was said to be quite excellent.