Gaslight via a mantle is quite different from SOX or any other electric lightsource and is surprisingly tricky to imitate well. As it is a point source of light, a large amount of light would not be expected except by providing more mantles.The colour encountered is a pale straw / lime green which is at variance even with candle light, although both forms are organic in nature. Tilley lamps although running on paraffin produce the same colour light as they also use mantles. Colour rendering is still distorted to a degree, with most colours dulled. SOX by comparison has a very marked distortion as has already been discussed.

That said, I think SOX is a worthwhile conversion and the gear should be easy to obtain. The secret is to either keep it discreet via "cut off" distribution (ie the lamp is shielded from view unless you are pretty much under it) or you go the opposite direction - everything out in the open and stuff the purists! That said, if the lamp is to be hung vertically, some form of ring refraction may be useful.

The use of aluminium as a reflector has already been suggested to reduce skyglow, however I suspect you needn't worry too much about that here for an 18W lamp, however there is nothing wrong with a little "discipline" to keep the light where you want it most. Bear in mind that many gas lanterns were traditionally fitted with opal glass on the upper panels, often to hide the mantle support etc.
Whilst aluminium has the benefit of being light and easy to work, the lack of upward light will take away the lantern's heritage or worse still make it look like just another reproduction.  Simple opal glazing would act as a reflector yet still allow some upward transmission. By designing the panels to work with the existing structure, they could be slotted or glued in place, whilst retaining the exterior glazing as fitted.

One of the opal panels would be drilled to accept a suitable bracket for the BC lampholder, whilst its neighbour opposite would have a lamp support attached. The support could alternatively be fitted on the horizontal panel in the top as per the diagrams. As has been already suggested by others, small gauge wiring would be ideal to hide within the lantern structure.

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"I can't think what you want to go to London for, you won't find any better lampposts there..."
L.S. Lowry. 1887-1976.

Very informative post and thanks very much for drawing up those diagrams.

Thanks, Alex. It was nice getting my thinking cap out again! I used to do this sort of thing back in the 90s.

Naturally, the ultimate decision to what should be done is down to the owner, but whatever is decided will certainly be of interest to the wider community here. If done sympathetically, it could possibly qualify for inclusion in the "restoration" section - but, is it restoration or conversion?

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"I can't think what you want to go to London for, you won't find any better lampposts there..."
L.S. Lowry. 1887-1976.

I would personally go down the same route, mounting an 18W lamp at the top inside a reflector so as to control where the light goes.

For one night I fitted an 18W lamp inside a similar lantern, hung vertically and at a similar height off the ground, and I went down the road to a point where there's a side road to have a look at the backs of the houses: about 3 houses in each direction from mine were being bathed in yellow light.

As this was only for 1 night there wasn't any comments but light pollution is an increasingly common issue in neighbourhoods now.... some councils even state that private lighting should not overspill onto a public road, and they may even state the maximum number of lumens provided by a private lightsource that can be shed onto a neighbouring garden (basically how bright the light is from next door).

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And vice versa (ideally)! Although many authorities state that streetlighting is not there to light up private property, it is amazing how much light is allowed to stray beyond the public thoroughfare. This is especially apparent in a quiet street where a 35W SOX at 5m is replaced by a 70W SON-T at 6m. The increase in mounting height, plus the fact that most new columns are set back from the road edge means that the stray light can be a real nuisance, especially in areas where terraced dwellings dominate the local scene.

With an increased awareness of this light pollution, it's no wonder that "anti glare" shields are often retrofitted to the newer HID lanterns. In the old days, a quick slap of black paint to a portion of the offending SOX lantern bowl would suffice!

In fairness, I had a similar problem with my own street lamp. Being a chopped down cast iron column with swan neck, the mounting height for the Z9480 lantern was only about 8'. Even with an 18W SOX, it was still a bit on the bright side. The solution to the problem was to obtain some expandable cable braiding. This is made of Polyamide / Polyester and is unaffected by the relatively low temperature of a working SOX lamp. Slid down the whole lamp length, the close weave structure reduces the visible light output down nicely.

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"I can't think what you want to go to London for, you won't find any better lampposts there..."
L.S. Lowry. 1887-1976.

Further to the discussion on light pollution from streetlighting (both public and private), I thought I would add this to the conversation.

It was taken from one of the national papers a little while ago so could be classed as old news. It might have even been showcased already on Ukastle.

Anyway, it gave me a chuckle when I saw it!

At first glance it is an amusing way of tackling light nuisance, however it does hint at a more serious point. It seems to me that much of the reproduction "heritage" lighting currently found in our towns and cities, is selected mostly on how it looks during the day.

Although harking back to a bygone age where most transport was horse-drawn, these lanterns fitted with tubular HID lamps and high performance optics, provide an light output quite out of scale with the streetscene the planners have wished to portray. In addition, the height of the columns is often quite simply just wrong.

I can see why the residents in the picture felt the need to do something about the intrusion caused.

On the subject of these repro lanterns, it is a pity the only designs to choose from seem to be modern interpretations of the old gas lamps. Why can't we have a "heritage" Viatron or Dioptron on a replica S&L column?

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"I can't think what you want to go to London for, you won't find any better lampposts there..."
L.S. Lowry. 1887-1976.