I wonder how many of you Nailsworthians out there realised that sitting on our doorstep is a fine collection of mighty electricity generator's that includes water, steam and diesel power. And no, i'm not talking about the wind turbine up at Nympsfield which of course comes under the 'Wind' category.

This collection covers a wide time period and is located in the very bowels of Longfords Mill. The giveaway was the huge iron pipe that connected the old mill building to the lake. The pipe was previously covered over, but the recent building work shows it in all it's glory. The pipe, which carries the supply of water from the lake connects into a water turbine, which connects via a drive shaft to a large flywheel and electricity generator.

The turbine is thought to have been installed around 1920 and was probably manufactured in either Sweden or Switzerland and is known as the 'Gordon Water Turbine'. A manufacturers plate attached to the turbine reads James Gordon Engineers and Contractors London. It has been suggested that James Gordon acted as a supplier of turbines made in Sweden, Switzerland and the USA. In operation, water from the lake is passed through the turbine, which consists of a horizontal cylinder set at right angles to the water supply pipe. The water is then output through a pipe at each end of the turbine casing, which then passes down through the floor into the stream below. The speed of the turbine is self regulating through various mechanical methods that are driven from the main output shaft. Pressure gauges showed the head of water above the turbine, and the amount of suction being created by the two water outlet pipes. With this type of water turbine the effective head of water is the sum of these two quantities, which at Longfords is approximately 25 feet.

The electricty generator that connects to the turbine was manufactered by Laurence Scott Electromotors of Norwich and Manchester, and has a rated output of 125KVA. The date on this is 1947, so it was obviously added later.

The next item found at the old mill is known as the Bellis and Morcom Steam Engine.

The engine is of the inverted vertical compound type and the order book entry states May 1904. The nominal output of the steam engine is 100BHP. The engine is thought to have arrived at Longfords Mill in 1917, after spending it's early life with Mather and Platt, who fitted it with one of their 75KW, 320 amp, 235 volts DC dynamos. The dynamo is still connected to the steam engine and looks like something that you would not want to stick your fingers into! Click on the picture of the steam engine and see a bigger picture along with a detail picture of the dynamo.

The final power generators are two very large diesel engines. The oldest, and biggest (and it is big) is manufactured by W H Allen, and is a six cylinder model rated at 232 BHP at 500 rpm. The Allen diesel is rumored to have been destined for a submarine, and to look at it you can see why. But further investigation shows this is not the case, as due to it's cast iron frame it would not have withstood the G-Forces created by a depth charge attack. The engine was installed at Longfords in September 1947 and is connected to a generator by a lots of drive belts.

The final diesel generator, the Petter Diesel, is newer and much more powerful than the Allen. It is also somewhat smaller, but it's still big! It was installed in the mid 1970's and is the four cylinder 'Superscavenge' model, which was produced in large quantities in 2,3,5,or 6 cylinder versions between 1936 and 1950. The diesel is connected to a Brush Alternator rated at 445KVA. For the inquisitive, the engine is rated at 384BHP at 600 rpm. The exhaust pipe from this engine is bolted to the mill building, beside the tall stone chimeny, which offers a stark contrast between the two time scales.

In use, the generators were thought to have been used in conjunction with the 'mains electricity' supply, which arrived some time during the 1920's. In later years the equipment was used as a standby power source if the mains supply failed. Apparently, it was used during the miners strikes of 1974 which enabled almost full production to be maintained at the mill, while the rest of Britain was suffering a three day week.

By clicking on the small images above, you can see a larger and other images of this fascinating equipment.

The future of the equipment is secured as it is intended to keep the collection together and hopefully allow public viewing when the mill conversion is finished.

More information on Longfords Mill (and the many other mills in this area) can be found by selecting the 'Old Mills' link on the main menu.

I have a small (300k) video clip of the above equipment.
Click here for the video

Acknowledgements
Thanks go to Dr Ray Wilson from the Gloucestershire Society for Industrial Archaeology for sending me a reprint of his excellent article in the 1992 Journal, and for allowing me to copy parts of it.

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