Technical Magazine Feature

Client: The International Society of Technical Communicators

Audience: Technical writers

This won the ISTC writing award. In it, you'll find the specs for a perpetual-motion machine developed around the turn of the century. By all means feel free to build your own, but if you make any money with it you owe me 10% of the gross takings.

THE ALTERNATIVE TO NUCLEAR ENERGY - A QUESTION OF GRAVITY

Introduction

The quest for a cheap, efficient source of electricity began when Edison's first bulb first started to glow. Nature has so far provided wind, fossil fuels, water and solar power, but these all have their drawbacks. No wind - no power. Supplies of oil, gas and coal will eventually become exhausted. Dams cause immeasurable ecological damage … and although solar power provides a welcome supplement to man's total energy needs, it cannot, as yet, cater for them completely.

As for the issue of nuclear energy, opinions differ. We are aware of its advantages and, more importantly, of the risk of catastrophe highlighted by the near-meltdown situation at the Three Mile Island power plant some years back. Were it not for the risks involved, nuclear energy could truly be hailed as the power of the future. But the risk of mishap, like the sword of Damocles, hangs over us all.

We need a new alternative.

As usual, the most obvious is overlooked, purely because we take it for granted. Hold this magazine at arm's length and release it. What happens? It travels, apparently unaided, in one direction - down.

Gravity - the prime mover. It keeps us where we are, brings things down to our level, but yet, as a power source, it has been ignored since the first apes dropped from the trees and discovered a whole new way of life on the ground.. Recent developments, however, could change this: evidence from a derelict forge in the Outer Hebrides shows that two Scots, Donald Pemberton and Obadiah Thring realised the potential that gravity offered as man's primary power source as long ago as 1874.

The Meeting of Minds

Donald Pemberton's childhood was unremarkable. Born in 1846, the youngest son of a Dumfries grocer, he showed an interest in the elementary physics taught at the local church school, but since he was expected to carry on the family business, this was hardly encouraged. He surprised the rest of the family when, at the age of sixteen, he left home, found work as a railway clerk and applied three times for an engineering scholarship at Edinburgh University. He was turned down each time.

He spent many evenings frequenting public houses around the university, meeting students and joining in their conversation. It was on such a typical evening three years later that he met and befriended Odadiah Thring. He was a nineteen-year-old engineering student, whose well-to-do family in Inverness had arranged for his education, board and lodging in Edinburgh in the hopes that once he had completed his studies, he would emigrate and take what they referred to as his 'infernal constructions' with him.

Thring's 'constructions', judging from his early notes and line drawings at university, had the peculiar characteristic of being sloppily designed, but meticulously assembled. In fact, his design skills were so inadequate that he was, when he first met Pemberton, under threat of expulsion.

Pemberton seized on this opportunity to become involved in Thring's engineering studies, and proved to be of invaluable assistance when it came to design problems. During the summer of 1867, however, the faculty discovered that this partnership was responsible for Thring's sudden marked improvement, and duly expelled him.

He returned home in disgrace, taking Pemberton with him, and very little is known about the pair until their marriage to identical twin sisters, socialites Clarissa and Penelope McNaughton, was reported in the social column of the Inverness Herald in July 1868.

Shortly afterwards, Thring persuaded the girls' father that with the appropriate financial backing, a large profit could be made from a funicular railway up the side of Edinburgh Rock, so that tourists could visit the castle at the top "without Distress & Exhaustion overcoming their Persons". After a great deal of deliberation, the money was reluctantly provided. Pemberton set about designing the system, and Thring supervised its construction.

All went well until the inaugural ride on August 11th, 1869 when, in front of visiting dignitaries and a large segment of the local population, the main drive shaft snapped, leaving the passengers suspended halfway up the Rock. Forty-five minutes later, as the hastily-assembled rescue team reached the car, their additional weight pulled it off its tracks and sent it plunging into the crowd of onlookers below.

By the time the resultant legal and insurance wrangles had been sorted out some four years later, Pemberton and Thring were destitute. It was only the timely inheritance from their father-in-law, whose health had deteriorated rapidly since the Edinburgh Rock disaster, that enabled them to take themselves and their families as far from the scene as possible. They eventually found Moran, a small island in the Outer Hebrides, where they bought a run-down forge some distance away from the only village, and settled into a more sedate lifestyle, raising sheep.

This proved too much for Clarissa and Penelope, who left the following year, taking the children with them.

Pemberton and Thring, however, were quite happy in their rustic environment. Now they had been left in peace, they were able to devote more of their time to designing and constructing such devices as their rotary sheep-dip and steam-heated feed-warmer, which, although hardly marketable, made their lives a little easier.

The Discovery

The inhabitants of Moran avoided the forge, and it was only in November 1985, nearly ninety years later, that anyone went near it. Sylvia Monroe, over from America to trace her ancestry, went to Moran and found the forge almost as Pemberton and Thring had left it. She discovered there, half-hidden among what she termed as "some old junk", a small tin box which she retrieved and took back home with her to Connecticut.

The box contained - amongst other things - a notebook filled with diagrams and notes. Sylvia's husband Lewis, Professor of Victorian History at Stamford University, was well-known for his keen interest in the technology of the time. On reading through those notes, he immediately flew to Scotland and from there made his way to Moran and had the rest of the "old junk" shipped home. With the aid of a colleague in the Engineering Department, Professor Daniel Saltz, together with a small team of interested volunteers, he set about completing what Pemberton and Thring had left unfinished.

It was incomplete because in May 1874 Pemberton's aunt, an elderly spinster living on the outskirts of Fort William, had succumbed to an influenza virus and required constant attention. The rest of the family were by now too involved with the new chain of department stores to look after her, so Pemberton left Moran while Thring carried on with their work until August, when he, too found it necessary to return to the mainland. Two weeks later, on his way to negotiate a contract with a foundry outside Inverness, his carriage left the road in mysterious circumstances close to the McNaughton estate, and he was found, dead of head injuries, some weeks later.

This news never reached Pemberton, who returned to Moran in September, and went back to raising sheep while he waited for Thring's return. In November, an unexplained outbreak of anthrax wiped out the livestock and, shortly afterwards, Pemberton himself, leaving, unfinished, a one-tenth scale model of (in his own words): "A Device to Produce a Constant Flow of Electricity by Means of the Centrifugal Motion of a Flywheel Sufficiently Empowered by its Own Momentum, Perpetuated by the Utilisation of the Gravitational Forces Attributed to this Planet". In short, the Pemberton-Thring Gravitational Momentum Generator.

The Design

According to Pemberton's notes, the full-sized Momentum Generator was to produce a constant output of 1430Kw at 21 amperes. The outer flywheel assembly was to revolve at 124 rpm, powered by the inner flywheel assembly and in its turn, powering a dynamo connected by a belt drive.

The outer flywheel assembly was a simple affair: two matching brass wheels 15 feet in diameter mounted on either side of the inner flywheel assembly. The outermost wheels powered the dynamo, while the inner wheels were driven by the inner flywheel assembly. All four outer flywheels were supported by two short axles, outside-mounted to leave room for the inner flywheel assembly between them, two feet forward of centre. Belt drives linked the inner and outer assemblies.

The inner flywheel assembly itself was a more complicated affair. It consisted, again, of two matching brass wheels, five feet in diameter, centre-mounted but with provision for a belt drive on either side of the spindle. Its main feature was a set of three free-rolling cylindrical 1¾-ton weights on each wheel, spring-loaded towards the perimeter and following channels in the wheels set at 120 from the centre.

The outside of these cylindrical weights had cog teeth machined onto them, which meshed with a corresponding set of teeth on the inside surface of lips around the inner wheels of the outer flywheel assembly.

Because of the relative sizes and positions of both flywheel assemblies, the cogs would only have meshed for an arc of 24 had it not been for the powerful steel springs pushing the weights outward and allowing them to slide towards the centre. These steel springs increased the arc of contact to 48 and, more importantly, while pushing out the weights, increased their downward momentum to the point that Pemberton had calculated was necessary to maintain a constant revolution speed.

Construction

Pemberton rightly deduced that any imperfection in an all-lead flywheel would eventually become exaggerated by centrifugal force and eventually distort it, perhaps with disastrous consequences. However, since lead was the most viable material to use from the point of view of weight, if not economy) to maximise the centrifugal effect of the outer flywheel assembly, Thring constructed it from brass, leaving a wide, hollow rim which was then filled with lead and sealed with a brass lip, overhanging (in the case of the inner wheels) towards the inside and cogged to accommodate the outside surface of the cylindrical weights.

The inner flywheel assembly was built after the same fashion - brass filled with lead, and likewise, the cylindrical weights.

Thring thought he had simplified construction by machine-tooling a single strip of cogged brass and cutting off the required lengths. However, he apparently encountered a great deal of difficulty forming the outside of the cylindrical weights and only solved that problem by producing another, similarly-cogged brass strip, but this time only half as thick.

Both sets of flywheels were mounted on brass supports and axles which, in turn, were attached to a wooden base, as was the dynamo. The dynamo in question was of the McLawrie type, a fact bemoaned by Pemberton and Thring after they had made arrangements to deliver it to Moran, when they learnt of a new model produced by Streatham and Jones in London. This, according to their calculations, would have increased the output to 1520KW.

Reconstruction

Professor Monroe wanted to adhere as closely as possible to the original design (bearing in mind that what he had shipped over to Connecticut was, in fact, only a one-tenth scale model) partly out of curiosity and partly from an aesthetic point of view. But the baseboard had long since rotted, and it was feared that the original brass flywheel assemblies had oxidised beyond salvation. Professor Saltz advised him to re-cast new flywheels from the originals, which proved to be a better course of action because hairline cracks had shown up under examination, the result of poor casting techniques in the forge at Moran. The original dynamo was replaced by a more contemporary model.

Rather than indulging in the seasonal festivities during the Christmas/New Year break, Monroe, Saltz and a small group of volunteers spent most of their available free time behind locked doors at the Metalwork Department at Stamford. Pemberton and Thring took over two years to get as far as they did, but the first working model of the Momentum Generator took just eleven days to evolve from thumbnail sketches and rough notes to a (theoretically) fully-working, one-tenth scale model.

Testing

Since the optimum power output was calculated to occur at 124 rpm, and the momentum effect came into its own at 104 rpm, it was obvious that it required more than a mere spin of the wheels to set them in motion. One of the volunteers disconnected the rear wheel from his 500cc Honda StreetHawk motorcycle and linked the engine via a drive belt to the left-hand outer flywheel assembly. This necessitated the disconnection of one of the drive belts between the inner and outer flywheel assemblies, but Professor Saltz foresaw no ill-effect other than a slight increase in strain on the two left-hand axles over a longterm period of use.

On January 26th, once the new dynamo had been installed and the baseboard had been securely fastened to a solid workbench, the honour of starting the motorcycle engine fell to Professor Monroe.

Progress was slow at first: a mixture of trepidation and internal mechanical resistance meant that it took three minutes to raise the rpm - measured by strobe light, to 104, when the gravitational effect of the cylindrical weights was calculated to come into play.

The team then lifted the motorcycle closer to the workbench, and when the drive belt was loose enough, it was whisked away with a crowbar, leaving the Momentum Generator running by itself.

Results

Some weeks later, when everything but the outer left-hand inner flywheel had been recovered, Saltz was carefully checking through Pemberton's notes to find the error in his calculations when it became apparent that the momentum of only one of the two sets of cylindrical weights had been taken into account.

Just how serious this error was can be deduced by the speed and trajectory of the outer left-hand outer flywheel, which had detached (as had the others) when the Momentum Generator shook itself to pieces. It had exited through a plate-glass window at a speed later calculated as approaching Mach 1.4, and from the evidence of splintering and shockwave damage 54 feet up the main flagpole in front of the City Hall (some three and a quarter miles south-west of the University) it was still accelerating at that point. It bounced once, leaving an eleven-foot furrow in the soft shoulder of US Interstate 91, two miles outside Yonkers NY, and finally came to rest 68 miles from its original starting point, embedded seven feet up in the side wall of a McDonald's in Newark NJ.

What astonished Professor Saltz was the interval between the disconnection of the motorcycle-powered drive band and the self-destruction of the Momentum Generator. It was impossible to measure the final rotation speed, but given that the rpm rate was doubling three times with every revolution of the inner flywheel assembly, the rate of acceleration became exponential within approximately 3/16ths of a second.

We can only be grateful, therefore, that the working model was only one-tenth scale - the energy created by a full-size version and its subsequent destructive power would otherwise have been phenomenal.

NASA, Consolidated Edison, The Central Electricity Generating Board and several foreign governments are currently examining the remains of the Momentum Generator, each with a view to constructing full-size versions, suitably modified.

Conclusion

It has been noted recently in the popular press that the difference between the Japanese and British workforces is that the former have been shown to be industrious but unimaginative, while the latter appear to be indolent but inspired. This could well be confirmed by the case of Pemberton and Thring, who - apart from their misfortune on Edinburgh Rock - hardly produced anything of any worth in their lives but who stumbled, more by accident than design, onto what could shortly replace every single nuclear power plant on earth, and become the most cost-effective, least risky and most environmentally-friendly power source that mankind could ever want or need.

London, April 1st

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