I haven't read Viz Comic since I was a schoolboy, but I can report that the meeting last night was packed, and the presentation demonstrated that the Transition Malvern Hills Lighting Group (a.k.a. The Gasketeers) are a highly professional organisation. They have fully restored 104 gas lanterns of various makes and styles, mainly Sugg Windsor pattern but also some Parkinson Cowan and other makes. In many cases they completely rebuilt and re-glazed neglected, corroded, vandalised and butchered lanterns. The work took around 18,000 man-hours, much of which was provided entirely by volunteers, all of whom are Gas Safe Register-approved gas lantern technicians. It appears that the expertise developed by this group is now in demand from the few other Local Authorities still operating heritage gas lighting schemes, notably the City of Westminster. One of the technical points I noticed was that the gas lanterns have four mantles, each rated at 250 watts (gas input) giving a combined light output of 400 lumens from 1kW of gas. By comparison, a nominal 300CP paraffin pressure lamp burns fuel at a rate of 750 watts. If anyone knows how to convert lumens to candlepower reliably, please let us know! Phil
There isn't really a direct conversion as they are units for slightly different physical properties... However I have seen a ballpark figure that 1 candela approximates to 12.6 lumens.
A bit about the Park Estate Nottingham with a brief mention of the gaslights... http://en.wikipedia.org/wiki/The_Park_Estate The article claims it to me the largest gas lighting network in Europe...
I know that this reply is a bit late, The 250 W Gas input per mantle is a total energy input as in .... about 850 B.Th.U. ...this is the hourly gas rate for a 1562 ,222 (size1 or bijou mantle) ... The actual light output of the mantle could be compared to 40W per mantle (compared to an almost extinct 40w light-bulb) ...50-55 candle power , 450 lumen each . That consumption of Natural Gas for each mantle is about 0.8 cu. ft./hr (Thus 3.2 Cuft/hr for four mantles),, or100l/h (0.1 cu.m /hr) for Napolean's measurement system. ...Interestingly those lamps at Malvern , which i visited when those works had recently begun mostly had burners in a shocking state of neglect , those burners had Size 2 (179) mantles which would have burned 5,000 Btu/hr for four mantles if they had been adjusted/maintained.(size 2 mantles are bit brighter they were standard in public lighting here in the u.k. These new burners at malvern have been inspired by German burners which have had to be optimised further and further to survive the ever continuing battle against the remains of Public Gas-lighting. As a reckoner with candle power and pressure lamps 10.35 Kw/hr are in 1 liter parrafin , that would power a petromax at 350 candle power for...10 hours say thus approx 1kW per hour total input to the petromax for the nominal 350 candles output ,,,, A coleman 200c.p. would burn 8 hrs or so? on an pint of fuel containing about 16,800 Btu . Thus for 2100 Btu /Hr input you get 200c.p, out of a coleman an the rest as heat . A Tilley , would burn at 8hrs on an imperial pint , containing approx 21,000 Btu..... this would be 2625 Btu/Hr for the Tilley's 250 or so c.p.
Oh , and to anyone eagle eyed who notices that the theoretical Tilley or Coleman or petromax in my examples above are burning somewhat more efficiently in regard to their light =output ,this comes mostly from there being a high pressure system and producing an higher temperature and thus more light output from the Welsbach Mantle....the Malvern gas lamps are a low pressure system , high pressure gas lamps like the bullfinch or equiv would have a similar efficiency to a tilley or Petromax.
There are several working gas lamps in Chancery lane, London, near the north end of the road. Attached to a military building, T.A. I believe. Easily viewable from the public road and footway. And as regards the merits of a high pressure gas supply, this was tried by William Sugg for gas street lighting in London towards the end of the gas light era. The burners were regenerative, whereby the gas and air were preheated by the output of the burners and thus burnt at a higher temperature. The running costs and efficiency were comparable with electric lighting. Back in the old days, when I was but a nipper, gas lighting was on the way out but by no means extinct. A significant minority of old fashioned homes and shops still used gas light. The last large or modernish shop with gas lighting that I recall was Woolworths, Surbiton branch. The gas lighting was still in working order in the mid 1970s, I remember it being used during the power cuts. The Bishopsgate Institute in London had a few working gas lights until a few years ago, they satisfied the rules regarding emergency lighting, and avoided the expense of battery backed electric lighting. These were not even incandescent mantles, but open flames. Some of my misspent youth was spent in Wood Green, north London. The Fishmongers arms public house had a nightclub/disco at the back and that was fitted with gas lights as emergency lighting. Late 1970s.
Should still be some around Westminster: Google Maps [snipped] I know (knew?) the Fishmongers Arms having been born and bred in Wood Green (Redvers Road). Redvers had gas lights until some time in the sixties when the sodium lights on concrete posts replaced them.
"Although gas lighting is now being threatened by our competitors, it is still a significant and valuable load. It is the duty of all employed in the gas industry to ensure that gas lighting installations are maintained, and that gas lighting is given due consideration for new housing schemes. Every gas light lost is an electric light gained, and every electric light gained is another opportunity for our competitors to sell current at inflated lighting rates and thereby subsidise the sale of electricity for heating and cooking, which as we all know is done better and cheaper by gas" Quote via my imperfect memory from a gas industry text book, just before the war. For decades, gas light was competitive with electric light and often cheaper. Gas light was undeniably cheaper in the winter when the heat produced reduced the need for other heating. What largely killed off as lighting was not any inherent superiority of electric lighting, but was the demand for other electrical appliances. Having faced the considerable expense of being connected to the electricity mains and having the house wired up, one might as well use electric lights. Radio sets, vacuum cleaners, and electric clothes irons were much demanded in the modern 1930s home. having paid the standing fee, electric lighting looked very attractive. Gas radios did exist but were costly and complicated and never popular. Gas clothes irons existed but were dangerous due to the flexible rubber gas pipe. I have never heard of a gas powered portable vacuum cleaner.
There used to be a type of gas light known as "hospital light" . Wall mounted and fitted with two incandescent mantles, the unique feature of these was that they had a continually burning pilot light between the two mantles and this was a small luminous flame with a light output of a couple of candle power. It was intended that the small yellow flame would provide night lighting in a ward sufficient for safe movement, and that the mantles would light instantly whenever a full working light was needed. To turn the pilot light/night light on or off needed a key, but the mantles could be turned on or off without a key, the key was also needed to open the fixture, for cleaning, mantle replacement or re-lighting the night light. These were sometimes fitted in domestic bathrooms, the night light was sufficient to use the WC at night, and turning on the gas tap would light the two mantles if full lighting was needed.
