By Rochelle Forrester
Ó All Rights Reserved
Publication Date 2006
The earliest
human knowledge of the power of steam comes from the classical world when Heron
of Alexandria described various machines using steam for such purposes as
opening temple doors or to blow a horn. The engines were used to amuse or
astonish rather than for practical or economic purposes. (Dickinson, 1963,
185-186). Claims have been made that the presence of slavery in Roman world
ensured that the steam engine was not used in industry as slaves were a cheaper
manual source of power. This argument can hardly be confirmed as we know little
of the price of slaves and how much they cost to keep in classical times so we
can hardly say that slavery made it uneconomic to develop an industrial steam
engine. It may well have been that for long periods in the classical world
slaves may have been expensive and a steam engine may well have been more
economic than slaves especially for difficult jobs such as getting water out of
mines. In any event it was impossible for the Romans to calculate the costs for
the development and manufacturing of a steam engine until they had actually
produced one. The most likely reason the Romans never developed a steam engine
was that the materials available were not strong enough or finely worked enough
to allow an industrial steam engine and their lack of understanding of the
principles of vacuums, atmospheric pressure and the properties of gases such as
steam. The Romans did not even have cast iron to work with, as cast iron only
became available in Europe after the invention of the blast furnace in the 14th
century. Roman iron was shaped by hammering which could not produce iron of
sufficient quality for the production of cylinders and pistons.
In the modern
period, from the Renaissance onwards, the earliest attempts to harness steam
power were toys or perhaps laboratory experiments similar to those Heron
described in classical times. Such devices were produced by Giambattista della
Porta (1536-1605) in Naples and Salomon de Caus (1576-1626) in England. (Rolt,
1963, 20-21). It is not known whether either of these men knew of the classical
steam engines described by Heron. The first sign of any attempt to use steam
power for industrial purposes were patents taken out in 1631 by a prolific
patentee David Ramsay “To raise water from lowe pitts by fire”, “To make any
sort of mills to goe on standing waters by continual moc’on without the helpe
of windes, waite of horse”, “To make boates, shippes and barges to goe against
the wind and tyde.” (sic) (Rolt, 1963, 23). All these aims were eventually to
be achieved by steam power, but only the first of them represented a pressing
social need of the times. This was the problem that water was getting into
mines and making the mining operations difficult or impossible. The extent of
the problem can be seen in that of 182 patents granted between 1561-1642 one in
seven was for the raising of water. (Dickinson, 1963, 16). The details of
Ramsay’s patents are unknown and there is no evidence any machines were
actually produced. The first attempt to actually produce a large scale machine
was made by the Marquis of Worchester in the 1660’s but there is some doubt as
to whether it was a genuine steam engine and in any event it was not a
practical success. (Rolt, 1963, 24-25). Worchester was followed by Sir Samuel
Morland who described a steam engine in a book he wrote which may or may not
have been the same machine mentioned in the diaries of a Roger North. Parliament
seems to have been supportive of these inventors granting both Worchester and
Morland a patent for their inventions, such as they were.
While this was
happening in England Evangelista Torricelli of Faenza (1608-1647), Blaise
Pascal (1623-1662) and Otto von Guericke (1602-1686) engaged in a series of
scientific experiments which showed the effects of atmospheric pressure and
that if a vacuum could be created the weight of the atmosphere could be a
useful source for the transmission of power. A further discovery relevant to
the development of steam power was Boyle’s Law which states the volume of a
given mass of gas varies inversely with its pressure when its temperature
remains constant. It is the pressure from the steam which lifts the piston, in
post Newcomen steam engines, and as the volume of the steam increases in the
cylinder as the piston rises its pressure falls allowing atmospheric pressure
to force the piston back down. As the piston falls the steam pressure in the
cylinder increases giving the steam its “spring” which then forces the piston
back up. The Newcomen engine worked by a weight attached to a beam which was
attached to the piston and the weight caused the piston to rise. The piston
would then be forced down when a vacuum was created in the cylinder under the
piston, which would cause the piston to fall due to atmospheric pressure above
the piston being greater than the pressure below the piston. A knowledge of
Boyle’s Law, how to create vacuums and the effects of atmospheric pressure were
crucial to the development of the steam engine.
Denis Papin
(1647-1712), a French Huguenot refugee from Louis XIV’s France, while in London
working for the Royal Society, produced the first working model of a steam
engine operated by atmospheric pressure. He placed water in a cylinder and lit
a fire under the cylinder. The steam in the cylinder caused a piston to raise
to the top of the cylinder and drive the air out of the cylinder. The fire was
then removed, the steam condensed and a vacuum was created within the cylinder
and the piston was driven down into the vacuum causing a weight attached to the
piston to raise.
The first to
come up with a practical working, although rather limited, steam engine was
Thomas Savery. He was from Devon, a fellow of the Royal Society, and was
granted a patent for “rising water by the impellant force of fire”. Savery’s
engine worked by steam alternatively entering two chambers and forcing water
out. The steam is then condensed to create a vacuum which then draws more water
into the chamber which is again forced out by the steam entering the chambers.
Savery produced a practical steam pump capable of continuous operation but with
the unfortunate defect of being unsuitable for pumping water out of mines as it
could only pump water to a height of twenty feet, not enough to get water out
of most mines. Furthermore the machine lacked a safety valve and was inclined
to explode on occasion due to the pressure of steam on the boiler. Nevertheless
Savery’s engine was the first steam engine to be sold commercially.
The first really successful steam engine was that produced by Thomas Newcomen, who like Savery was from Devon. H. W. Dickinson comments that Newcomen’s engine “was little more than a combination of known parts” with one or two additional ideas of Newcomen’s added to it. (Dickinson, 1963, 29-30). Burstall considered Newcomen’s engine
“came about as the culmination of a series of advances that had been made during the preceding two centuries and it is most likely that it Newcomen had not built the first engine of this kind someone else would have done so very soon afterwards; indeed Denis Papin very nearly did, for he was experimenting with the condensation of steam in a cylinder, a few years earlier, but he was not a practical mechanic and he was defeated by the mechanical difficulties.” (Burstall, 1963,191).
Another interpretation by L. T. C. Rolt is that:
“The wonder is not that Newcomen spent anything from ten to fourteen years on his invention before he achieved success but that such a staggering advance could have been made by one man in a lifetime. ... Seldom in the history of technology has so momentous an invention been developed by one man so rapidly to so definitive a form. When, in addition we remind ourselves of the, to us, unbelievably primitive means at Newcomen’s disposal in 1712, then we can scarcely fail to regard his achievement with a wonder akin to awe.” (Rolt, 1963, 65).
Rolt does seem to go over the top in his
admiration for Newcomen’s achievement.
The Newcomen
engine worked by using a weight attached to a beam to force a piston to rise.
The piston would then fall due to a vacuum being created under the piston by
the injection of water into the cylinder which caused the steam to condense,
reducing pressure under the piston to a level below atmospheric pressure, which
forced the piston down. The beam attached to the piston operated a pump to pump
water from the mine.
In the years
following 1712 Newcomen’s engines began operating in mines all over England and
also in Scotland, Wales and in Hungary, France, Belgium and possibly in Germany
and Spain. (Dickinson, 1963, 51). Later in the 18th century, after a scientific
study, various improvements were made to the Newcomen engines by John Smeaton
which considerably increased their efficiency. An important reason for the
success of Newcomen’s engine over the Savery engine was that Newcomen’s was an
atmospheric engine that did not need to use steam pressure any higher than that
of the atmosphere. (Dickinson, 1963, 29). Savery’s engine in order to lift
water from mines required a steam pressure greater than that which the boilers
built in his time were capable of withstanding. Increasing the steam pressure
would cause Savery’s engine to explode.
The next significant
step in the evolution of the steam engine came when James Watt was asked to
repair a model of a Newcomen engine. He studied the model and realized there
was a great wastage of steam resulting from the heating of the cylinder and its
cooling at each stroke. In 1765 it occurred to Watt that if a separate vessel
containing a vacuum was connected to the cylinder the steam would rush into the
separate vessel and could be condensed without cooling the cylinder. The
separate vessel, commonly called the separate condenser, was patented in 1769
and the patent was later extended by Parliament for an extra 25 years. The
partnership of Boulton and Watt was formed in 1773, trials were made and the
new engine was found to have extra power and to use one quarter of the fuel of
the Newcomen engine. (Dickinson, 1963, 74). Sales were soon being made to mine
owners around Great Britain and Europe.
However for the
Watt engine to become truly revolutionary it had to be capable of rotary motion
which would allow it to drive all kinds of machinery. Experiments had been made
to get rotary motion out of Newcomen engines with some limited success.
(Dickinson, 1963, 64-65). Watt was eventually able to create a rotary engine
although it required many changes in mechanism; steam was required to act on
both sides of the piston and new mechanisms were invented to connect the beam
to a rod to turn a shaft which gave the rotary motion. (Dickinson, 1963, 80).
The first rotary engine was created in 1783 and by 1787 the design was standardized.
This ensured the applications of the steam engine were greatly increased and in
its use in the textile industry the rotary steam engine was to become the
driving force of the industrial revolution.
A further
improvement initiated by James Watt involved the use of expanding steam. In the
early Watt engines steam was admitted throughout the whole fore-stroke and
energy was wasted when steam still under pressure at the end of the stroke left
the cylinder and entered the condenser. To solve this problem Watt stopped the
admission of steam into the cylinder when the piston had made only part of its
stroke, the rest of the stroke being performed by the steam expanding from
boiler pressure to the low pressure of the condenser. This resulted in better fuel
economy for the engine. (Thirring, 1958, 51). The Cornish beam engines,
developed by Richard Trevithick after 1812, were similar to Watt engines but
used steam at a much higher pressure (40lbs per square inch rather than 5) than
was used in the Watt engines. This enabled a much earlier cut off for the
admission of steam into the cylinder at about one ninth of the stroke so
allowing a still greater expansion of the steam.
Yet another
development concerned the invention of a compound engine with two cylinders by
Jonathan Hornblow in 1781 which was developed by Arthur Woolf in 1803. Steam
first enters a small cylinder, where it expands from boiler high pressure to an
intermediate pressure and then enters a larger cylinder, where it expands down
to condenser pressure while performing work against a piston in each cylinder.
This gives a better uniform motion and reduces loss of energy caused by the
alternative heating and cooling of the cylinder walls.(Thinning, 1958, 51-52).
The improvements made to the steam engine increased its thermal efficiency as shown by the table below.
|
Date |
Type |
Thermal
efficiency (percent) |
|
|
|
|
|
1750 |
Newcomen |
0.5 |
|
1767 |
Modified by
Smeaton |
0.8 |
|
1774 |
Further
modified by Smeaton |
1.4 |
|
1775 |
Watt |
2.7 |
|
1792 |
Watt Expansive |
4.5 |
|
1816 |
Woolf Compound |
7.5 |
|
1834 |
Trevithick
Cornish |
17.0 |
Source:
(Burstall, 1963, 279)
As the steam engine improved its uses grew from pumping water out of mines, to driving machinery in factories, to its use in transport such as railways and steam ships.
The social and cultural effects of the steam
engine were immense. The steam engine was to be the driving force of the
Industrial Revolution. It was to become the main power source for the factories
that arose initially in England and eventually in the rest of Europe and the
USA during the 19th century. It was to result in a massive transfer of labour
from working in agriculture to working in manufacturing and industry. Steam
engines were to power textile mills in England and were later used for digging
and moving coal, for smelting and manufacturing iron and steel and in the
printing industry. Steam power was also used in agriculture to power threshing
machines.
The use of steam power in industry was to
result in a massive expansion in the size of towns and cities, so that the
majority of the population of industrial states were to live in an urban
environment. Conditions in the rapidly growing cities for the workers and the
poor were often crowded and filthy leading to the growth of trade unions and
political ideas such as socialism and communism. Living standards of the urban
poor in industrial societies were soon to improve and democracy was to become
the principal political system for industrial states replacing more or less
absolute monarchy which had been the principal political system of societies
based on agriculture.
Steam power was also used in transport,
especially in railways and in shipping. Railways spread throughout Europe and
the United States in the 19th century leading to a much more mobile population
and to the more efficient movement of trade goods. Steam ships were to lead to
a massive expansion in international trade in the 19th century and to vast
migrations of people especially from Europe to America. Improved transport was
to help make famine, often a problem in agricultural societies, a rarity in
industrial societies, likely to happen only in unusual situations such as war
time.
There were a
range of factors that influenced the development of the steam engine. A real
and significant need was a major factor in the development of steam power. The
problem of water getting into mines would have existed all over Europe, but was
particularly bad in Great Britain which had the largest mining industry in
Europe. By 1650 British coal mines were producing five times as much coal as
the rest of the world and mines were becoming deeper and extending further
underground. (Lewis, 1971, 10). Output is estimated to have expanded from
200,000 tons in the 1550’s to nearly 3 million tons in 1700. (Buxton, 1978,
11). In these circumstances the need to get water out of mines was largely a
British problem so that it is not surprising that the British were the people
to solve it. That this was a considerable problem can be seen in that one in
seven of the patents granted between 1561-1642 related to the need to get water
out of mines.
Considerable
scientific progress had been made in the years preceding the invention of the
steam engine. The principles of vacuums, atmospheric pressure and the
properties of gases such as steam had been discovered by Boyle, Torricelli and
von Guericke immediately before the invention of the steam engine. We do not
know the exact process by which Newcomen invented his engine, but it seems
hardly possible that he could have invented the engine without a knowledge of
the properties of vacuums, atmospheric pressure and of gases. Papin certainly
knew of Boyle’s Law and of the properties of gases, vacuums and atmospheric
pressure. From 1675-1679 he worked as Boyle’s assistant and he was an expert
designer of air pumps and air pump experiments. Air Pumps were used to create
vacuums and to control the air pressure within a container. Air pumps were a
key element in the discovery of the properties of gases, atmospheric pressure
and vacuums. The principle that the heating of gases under a piston would force
the piston to rise, is not something that can be obtained by simple
observation. It could only be obtained by experiment. Watt and the other
improvers of the steam engine would hardly have attempted to use a gas to lift
a piston unless they knew that gases expand when heated. It is this vital bit
of knowledge, unknown before the propagation of Boyle’s Law in the 17th century
that allowed the invention of the post Newcomen engine. James Watt had
considerable scientific knowledge and it was his knowledge of Black’s theory of
latent heat that lead to his invention of the separate condenser.
One of the
principal difficulties facing those who tried to develop steam power was the
low quality of the materials they had to work with. As Dickinson said
concerning the problems Newcomen would have faced “chains would break, pipes
would burst, leather would tear away and incrustation would form in the boiler
and on the interior of the cylinder.” (Dickinson, 1963, 35). Dickinson also
attributes the failure of Savery’s engine to imperfections of workmanship and
unreliability of materials and in particular to the inability of tradesmen at
that time to make boilers able to withstand a substantial amount of steam
pressure. (Dickinson, 1963, 35). It is much more likely that these sort of
technical problems and their lack of knowledge of how to create a vacuum
stopped the Romans developing a steam engine, than slavery did. By the end of
the 18th century the situation had improved greatly with Watts engines having a
much higher standard of workmanship in the making of its valve, valve gear and
in the boring of its cylinders. Engine building had begun to move out of the
hands of millwrights and into the hands of specialist manufacturers. (Rolt,
1963, 135). Dickinson considered new techniques for the boring of cylinders,
introduced by John Wilkinson, were vital to the success of Watt’s engine.
(Dickinson, 1963, 74). Equally the high pressure engines produced in the first
half of the 19th century were dependant upon improved workmanship and materials
to stop boiler explosions. It seems clear that progress in the metal working
trades was a vital factor in the development of the steam engine without which
the steam engine would not have been developed or would have remained a crude
inefficient device restricted to pumping water out of mines and would not have
become a key factor in the industrial revolution.
A further point
that emerges from our study is the move from simplicity to complexity in engine
development. When John Smeaton, who did so much to improve the Newcomen engine,
first saw a Watt engine he considered it a pretty engine, but to complicated.
(Rolt, 1963, 134). The move to greater complexity involved adding things to the
engine such as the separate condenser, a second cylinder, expanding steam and
rotary motion to improve its performance. Such progress had to be made one step
at a time and in a particular order as the problems which were intended to be
solved by adding to the complexity of the engine would only become apparent at
an earlier stage of the engines development and the solutions were sometimes
dependant upon newly acquired knowledge which arose only from practical
experience in using the engines. Only when these problems became apparent was
it possible to attempt to solve them, so the steam engine grew from a simple
idea to a more complicated engine as people attempted to improve it.
The social conditions necessary for the development of the steam engine were a society where the free communication of ideas was allowed and encouraged. The steam engine was not invented by any one man and it was necessary for all those involved in its invention to be able to freely communicate their ideas and inventions. It was an invention that had its origins in antiquity and was actually developed over a period of about a 100 years by a number of separate individuals. The steam engine was invented both due to individual brilliance on the part of those who contributed to it but also due to a considerable diffusion of knowledge between those contributors. Certainly James Watt developed his engine from a model of a Newcomen engine. Another improvement Watt made to the steam engine to give it rotary motion was a conical pendulum centrifugal governor which ensured the steady motion of the engine, even when the load on it varied. The same system was used in flour mills to regulate the speed of mill stones. (Dickinson, 1963, 83).
A crucial point
is that those who worked on steam engines published accounts of their work. That
is how we know of their work and that is how they would have learnt of each
others work. Giambattista della Porta published his work in his Spiritali in 1606, the Marquis of
Worchester published his in his A century
of the names and scantlings of the Marquis of Worchester’s inventions; Sir
Samuel Morland in a chapter of a book he wrote, the chapter being called The principles of the new force of fire
invented by Chevalier Morland ...; Thomas Savery in a book called The Miners Friend; while Denis Papin published
his work in Philosophical Investigations.
The publishing of the work done by these men played a crucial role in the
diffusion of knowledge of steam power and allowed each man to build on the work
of his predecessors. It should be added that in many cases there was
confirmation of the work of these men from other sources such as other peoples
books and diaries, British government state papers and the granting of Letters
Patent. That the knowledge of the progress of steam power was reasonably widely
known, at least within the circles of those interested in it, was shown by a
poem written by Henry Beighton known as the Prize
Enigma in which Beighton recites the history of the work done on steam
power by the Marquis of Worchester, Savery and Newcomen. That Beighton
apparently knew both Savery and Newcomen and knew of Worchester’s work strongly
suggests that Newcomen and Savery would have known of each others work and that
of the Marquis of Worchester’s. Further elements in the diffusion of knowledge
of steam power was the presence of organizations such as the Royal Society and
that the work was to some extent concentrated in particular areas such as
London, where the Royal Society and the English court were located, and Devon.
There were a number of conditions necessary for the invention of the steam engine. A vital one was the presence of a need, initially that of how to get water out of mines and later how to drive the new machinery that was being produced as part of the industrial revolution. But needs are common and they are not always met. The reasons why those needs were met was due to the scientific progress that was going on in 16th and 17th century Europe concerning the knowledge of atmospheric pressure, how to create vacuums and of the properties of gases. Allied to this scientific progress was a belief in Europe at the time that progress could be made and problems could be solved. The inventors at the time such as Papin, Newcomen and Watt applied the scientific knowledge to solving the problems that existed and after long periods of trial and error were able to produce a working steam engine (Newcomen’s) which was then improved to become Watt’s engine. Crucial to the progress made by the inventors was the diffusion of scientific and engineering knowledge which enabled them to build on each others work. The earlier development of printing was vital to the diffusion process and the role of organizations such as the Royal Society was also important. Poor quality materials was a great difficulty facing those trying to construct a workable steam engine. Once this difficulty became apparent at the start of the 18th century with the Savery and Newcomen engines, work was done to improve the materials so that Watt’s engine, which required better materials was able to be built.
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