Re: Re: Dublin Street Lighting

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Simon Cornwell

@Graham Hickey wrote:

Brilliant stuff Simon – thank you for that information.

No problems. Glad it was of interest.

@Graham Hickey wrote:

So is it likely they were made in the UK? And what caused the shift to the use of concrete in the 1930s do you know?

Previous to the 1938 installation, I expect all of Dublin’s cast iron columns and brackets were cast and produced by local foundries. The old gas lanterns were probably produced by local firms as well, although specialist gas lantern manufacturers were appearing by the mid 1850s.

The idea of using concrete for columns probably originated from the USA, where the first concrete street lighting columns appeared in the 1900s. Concrete was touted as a solution to all the problems with cast iron and/or steel: it didn’t rust, it didn’t require maintenance (i.e. a costly and timely repainting rota) and it has double the life of an iron or steel column.

It’s acceptance was slow, probably due to the columns and brackets being bulky. But with the steel shortages of the 1940s and 1950s, concrete was used more and more frequently.

Dublin was certainly a very early adopter of concrete. In 1938, there would’ve only been a handful of manufuacturers who could’ve made them: take your pick from Concrete Utilities (who definitely produced lots of special designs for particular towns and cities), Stanton and/or REVO. I might be able to identify the manufacturer from the door at the base of the column, as many used their own locking mechanisms. If someone could photograph the door on one of the remaining Dublin columns then I’ll try and identify the maker.

(I saw some other concrete columns in Dublin and noted they were by Concrete Utilities and Stanton. So, again, a mixture of suppliers was used over time).

@Graham Hickey wrote:

I’d often wondered about those refractor rings you mention inside the lamps…

…can you explain what you said about directing the light out into the street a little more? Do you mean it directed the light out in all directions in a 360 degree manner, or just specifically out to the roadway?
Certainly the appeal of these lamps for me has always been the multi-directional light emitted – very efficient.

By suspending a bare light over the road, you’d achieve a circular distribution of light around the column. In some cases, this was desired, and bare bulbs with little or no optical control were used. There’s some examples of those in the park, the BTH Parish lanterns being cases in point, having just a spun steel enameled over reflector to reflect light above the lamp back down onto the road.

But the idea of street lighting is to uniformally light the entire street surface so that any obstacles (such as cars, pedestrians etc.) would be shown in high constrast. (A principle called silhouette lighting, which started to gain ground in the 1910s and 1920s). Therefore lanterns were designed to cast their flux up-and-down the road’s axis, and by positioning the columns correctly, the whole road could be evenly illuminated.

Diagrams of the principle is shown here:

This was achieved in practise by using mirrored lanterns or glass refractors. See the bottom two diagrams on this page:

The two plan candle-power distribution curves show how the light is directed by the refractor ring. If lanterns were strung across the centre of the carriageway, then the 180 degree refractor ring would be used][/url]

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