Undercover - Steam Power - Book 5

Part 4 - The devil of rotation

'Well, Mr Vernier, if ye are what ye say, ah have need of such a man for ah'm plagued with men who presume to understand the workings of the atmospheric engine but canna comprehend the workings of steam.'

'Why do you call it an atmospheric engine,' Licia asked.

'Because, laddie, the cylinder is filled with steam at atmospheric pressure and when this is condensed a partial vacuum is created and the weight of the atmosphere pushes the piston down. I cannot use high pressure steam to do the work because I canna get a cylinder bored accurately enough to prevent the steam escaping.'

 'Most of the old boring machines are only good for gun barrels and water pumps up to nine inches (23 cm) diameter. Whereas I need a cylinder up to six feet (182 cm) diameter and eight feet long.    Mr Wilkinson is the only person capable of making a cylinder the least accurate, although it still lacks three-eighths of an inch (1cm) of being truly cylindrical.'

Mr Watt consulted his wife and returned to us. 'I am on ma way to the tin mines in Truro to work on one of ma engines,' he said. 'Perhaps y'd like to travel with us. From what yeh tell me, Lee can defend us against highwaymen and the rest of yeh can push when we get stuck. Now, as soon as yeh have all finished eating, I think we'll be on our way.'

We were all delighted to get a ride. The prospect of walking all the way to the mines was not appealing and we thanked Mr Watt profusely. But there wasn't enough room for all of us inside the carriage, even after the driver had moved some of the luggage, so Alfie and Miguel volunteered to sit with the driver and the rest of us squeezed into the seat opposite Mr and Mrs Watt.

 Meanwhile, Jonathan had re-harnessed the horses and turned the carriage around.  I looked for Dunc but he had taken flight and was on his way westward surveying the way ahead of us. As we lurched over the potholes, Mr Watt regaled us with the story of his previous journey to Truro.

 'When I travelled from Birmingham to Truro last year, I thought the new toll roads and stage coaches would make the journey tolerable but most of the coaches were full and, after Plymouth the roads were only passable with pack horses or sleds. The roads have-na been good since the Romans left us. The wagons, they have down here, have wheels with rims eighteen inches wide to navigate the terrible ruts and pot holes. It took us five days to travel 250 miles. This time the weather is a little drier and I am assured the main roads have been repaired.'

'But, I must confess, travel is easier than it was twenty years ago. When I was a young man, there wasna a stage coach between Glasgow and London and I was advised to go by sea but I had no wish to risk ma life in a boat. I had to buy a horse to make the journey and then ah had to sell it to pay for ma apprenticeship to an instrument maker.'

Mr Watt then launched into a technical discussion with Denny on the design of boring machines. 'What you need is a very rigid turntable driven by a steam engine,' Denny declared. 'Waterwheels are not powerful enough for the job.' 

 And that started them off on talking about the difficulties of converting the straight up and down motion of the atmospheric engine into a rotary motion. Mr Watt shook his head doubtfully. 'Ma business partner, Matthew Boulton, is forever nagging me to build a circular engine or steam wheel,' he said. 

 'He told me, "I don't mean to hurry you, James, but there is not enough rain to turn all the water wheels needed by the spinning jennies and weaving machinery. The people in London, Manchester and Birmingham are all steam mill mad."' 

 Mr Watt continued, 'Mathew Bolton has installed a fire engine to pump water back up to his mill pond so he can power his punches and stamping machines. But, ah'm too busy keeping these old pumping engines working to build steam wheels or rotating fire engines. The circular steam engine will need to be double acting and the piston rod must be stabilized with a linkage to keep it running straight. When ah've solved these problems, surely the devil of rotation will be afoot.'

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