Tuesday 29 October 2019

Setting up Siemens Industrial Museum at Woolwich in the 1950s

Setting up Siemens Industrial Museum at Woolwich in the 1950s
Ian Lovell describes potential exhibits which they found in the vaults

The Siemens Water Meter which we exhibited was not a genuine historic item but a reproduction built to demonstrate the principal. Its appearance bore scant resemblance to the original. It consisted of a simple turbine connected to a mechanical revolution counter.  It came with an electric pump and plastic pipes to make connections

There was a Siemens W 40 Magneto Electric Machine about 3 feet long and 2 feet high painted black and immensely heavy.  It was an A.C. generator using permanent magnets for its field; it could still produce a deflection of an AVO meter when turned by hand

The Original Swan Lamp had been the size and shape of a cigar with a carbon filament.  The original our research showed, has been insured for £2,500 but accidentally broken some years before. A copy was made said to be identical. It certainly looks exactly like the photographs we saw of the original. It was insured for £1,500. The insurers made it a condition that the copy should be kept sealed in a mahogany case with heavy beveled glass sides - not ideal for the exhibition purposes.  The Victoria Lamp as we named it was a green glass bulb the size of a Christmas tree light in the form of a bust of Queen Victoria. Dr Sutton had checked the filament and found it to be good. He was particularly anxious that there should be a power supply for this for the Duke of Edinburgh to light up. He felt he (the Duke) would be especially interested in the exhibit as he was related to Queen Victoria by marriage.  I was set the task of determining the operating voltage as there was nothing on the bulb to indicate this and arrange for a suitable transformer to be built if necessary.  I built a simple rig with a voltmeter and variable transformer and starting at zero applied voltages increasing in steps of 0.2v to it. It was a very nerve wrecking experience. At 3.2v there was the faintest detectable global from the filament, At 3.6v it blew.  I thought it would not be astute from a career point of blew to tell the director that I had destroyed an irreplaceable historic relic on which he had set his heart, courteous and charming that he was.  I therefore told him I had tested it and found it blown and he believed he had done it himself

There were also a number of other carbon filament and early tungsten bulbs, none working and some early thermionic valves.  I remember one bulb which had two long strips of brasses terminals. Its holder was a piece of polished wood which fitted between the strips. The bulb was screwed with a wooden nut and bolt passing through holes in the terminal strips which lined up with one in the wooden support

The Sound Powered Telephone, built in 1893, resembles an elegant brass and mahogany mushroom. It had an elaborately turned brass base on which was mounted a leather covered brass column which acted a handle. This was surmounted by a tamed mahogany earpiece which also served as a microphone. Mounted on the side of the handle was a small crank connected through a gear chain to a magneto inside. When not in use a metal bead rested on the diaphragm which rattled loudly when the magneto was cranked to call the other user.  The bead was threaded on a bootlace connected to the telephone to prevent it being lost

The Master Clock was  a very accurate wall mounted long case instrument designed for  factory use, powered by a battery. It was driven by magnetic pulses applied to the pendulum by a solenoid. An ingenious device ensured that the pulse was applied only when the amplitude of the pendulum had dropped below a certain distance, usually one every six or seven oscillations. Once a minute the clock would transmit an electric pulse from each of the two terminals.  The pulses on alternate terminals being 30 seconds apart.  These pulses had been used to drive slave clocks round the factory enabling a number of relatively inexpensive instruments to achieve the same accuracy as the master instrument.  This instrument was not displayed in the museum

Siemens had been associated with a number of other artifacts not exhibited but referred to in pictures reproduced from books.

The Super Regenerative Furnace. The exhaust gases instead of being directly released into the air were passed through a honeycomb of firebricks, heating them. When the honeycomb was sufficiently hot the exhaust gases were re-directed by metal door to a second honeycomb and the air inlet to the furnace through the previously heated bricks. The brick honeycombs were then switched at appropriate intervals as one cooled and the other heated.  This resulted higher temperatures and lower fuel use being achieved by reusing heat which would otherwise run to waste

The Super Regenerative Steam Engine invoked a similar principal. Steam exhausted from the engine was used to heat the feed water before it was pumped into the boiler making a considerable saving of energy. This was done with a simple heat exchanger consisting of two concentric pipes

Siemens Engine Speed Governor was said to govern the speed of a steam engine more accurately than the centrifugal engine governor. It comprised two shafts one of which screwed into the other and one of which could move longitudinally.  One shaft was connected to the load the other rotated at a reference speed controlled by a pendulum. If the shafts turned at the same speed there was no longitudinal movement .if there was a difference of speed one shaft would move along lengthways and a collar on it would operate a lever to adjust the steam Inlet. I’m still puzzled as to how a shaft running at constant velocity could be regulated by a pendulum

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