I hesitate to correct you Roy since I've come to regard you as one of a select group able to provide a 'definitive' answer or definition on historical mining practice. (Here comes the 'however') However the responce you gave made it read as if a Savery was employed at Dudley when in fact a Newcomen engine was erected. I'm sure that you know this since you note the replica engine at the Black Country Museum, but people unfamiliar with the area could be confused.
I'm a Blackcountryman by birth (someone had to be!) but live in Herefordshire now. Do they still say "Ow am Ya?" instead of "have a nice day" at McDonalds?
Sorry, I really apologise if I was misleading, I should have emphasised that the 1712 engine was of course a Newcomen.
But I did equate Savery’s with the chocolate fire guard, and would have thought the implication obvious that the 1712 engine a different design.
Now as a special punishment for picking me up I shall bore you with an extract from a book that I am writing.
Reads:
Now believe it or not, it was as early as 1698 that a Mr Thomas Savery secured a patent for a machine that he had developed described as “a machine for the raiseing of water by the impellant force of fire”, to “be of great use and advantage for Drayning of Mines” Looking back through history one encounters inventions that appear startling taking into consideration their time. Like Puckle’s machine gun of 1718, there is some conjecture about whether or not these inventions actually worked, never mind saw service. Savery’s engine is however accredited with being able to lift water for height of more than 50 feet, OK it worked, but just about as useful as the proverbial chocolate fireguard in a deeper mine.
About the same time, Thomas Newcomen was working on the same problem. The result was the first of what was to become known as “the Cornish beam engine”. Newcomen’s design was a large cylinder with an internal piston connected to a massive overhead beam pivoted on the outer wall of the engine house. Filling the cylinder below the piston with steam and then rapidly condensing it with a jet of cold water would cause a vacuum in the cylinder, therefore allowing atmospheric pressure to force down the piston drawing down the indoor end of the beam. The outside end of the beam would be connected to a timber pump rod running down the shaft the weight of which would be raised by the engine. The descending weight of the pump rod would force upward the column of water in the rising main. The mechanism of this I will describe later. This type of engine became logically known as the “atmospheric engine”. Metalwork such as in pipe work and boilers in those days wasn’t up to very much, and the big advantage was the very low steam pressure required to operate the engine. Boilers were very crude, however at this very low pressure leaks could be patched with nothing more sophisticated than a sod and a brick! The big problem was efficiency. These engines would consume huge quantities of coal for the work that they did.
However, this engine, which unlike Savery’s was self-acting, was immediately successful and one was first installed in 1712. This was not in a metal mine but in one of the Earl of Dudley’s coal mines in the Midlands, not far from where I live. This engine became logically known as “the 1712 engine” and is regarded as a milestone in the development of mining practice. In fact a working reproduction can be seen today at the Black Country Museum at Dudley, West Midlands. This is a good day out, trust me.
Later James Watt was to develop the true steam engine. That is one working on the pressure of steam itself. Many different designs were in use during the nineteenth century, which are way beyond the scope of this book. However, it is appropriate to describe briefly the workings of the later examples. By the second half of the nineteenth century the optimum working pressure of 40 pounds per square inch was fairly standard. Three valves, the steam, equilibrium, and exhaust valves operated the engine. Steam at full working pressure was allowed into the cylinder above the piston, therefore forcing it down the bore of the cylinder. At a certain point the valve would close, thus allowing the expansive power of the steam to complete the stroke. This completed the power, or “indoor” stroke, raising the heavy pump rods in the shaft. Next, the weight of the pump rods would cause the beam to tilt in the other direction raising the piston back up the bore of the cylinder, known as the “outdoor” stroke. Now, and this is where the genius of the design comes in, the equilibrium valve would open thus allowing the now ‘spent’ steam to fill the cavity below the piston. Just before the piston reached the top of the cylinder the equilibrium valve would close to cushion the final movement of the piston. Next the exhaust valve would open allowing connection of the space below the piston with the condenser. This would cause the steam in this area to condense thus creating a vacuum below the piston. This vacuum below the piston was necessary to initialise the power stroke before the steam valve opened. However, it can be easily appreciated that this engine now harnesses both the power of high pressure steam with the power of atmospheric pressure as used in the earlier Newcomen engines. The valves were operated automatically and all that was required to get the thing started was to complete a few strokes by manually operating the valves, once vacuum was obtained below the piston it would run on its own. This design of engine was to reach its heyday in the 1880s, even seeing service well into this century. The massive 90 inch engine at Taylors Shaft at the East Pool mine in Cornwall was in use up to 1954.
My avatar is a poor likeness.