Newcomen's fire engine

Illustration from Beck, Ludwig: Die Geschichte des Eisens. Bd. 3: Das XVIII. Jahrhundert. Braunschweig, 1897; colourized by Günther Schmalz (C) 2023.

Newcomen's engine raises the water entirely by the pressure of the atmosphere ; for the steam is employed merely as the most expeditious method of displacing the air, and then producing a void, into which the atmospherical pressure may impel the first mover of the machine [1].

A Newcomen steam engine has no need of steam of great or dangerous pressure for it operates with very moderate heat. It was safer than a Savery pump. The power of Newcomen's engine is not bounded by the strength of the boilers, and vessels, to resist internal pressure, but only by the dimensions which it is practicable, and expedient to make boilers, and cylinders, to contain the requisite quantity of steam, of the ordinary pressure, and the strength which can be given to the working lever, chains, and other parts, which communicate the force of the piston, to the rod of the pump. Newcomen's engine can also be applied to other mechanical purposes, besides that of raising water. For instance, to blow air by bellows or pumps, into a furnace; or, by connecting a crank and fly-wheel with the rod, which is suspended from the extremity of the great lever, the reciprocating motion of the great lever may be changed into a circular motion. It took however another 50 years after the first erection of a Newcomen engine before a crank and flywheel were applied to a Newcomen engine. Savery's engine is necessarily restricted to the purpose of raising water, and could not be applied to work mills, except by the intervention of a water-wheel [2].

We see from historical documents that at Newcomen's time the technology was not advanced enough to cope with steam pressures much above atmospheric pressure. Savery must have used at least 2 atmospheric pressures above the pressure of the atmosphere to push up water to 20 meters. Increasing the pressure to achieve higher heights caused from time to time problems with the boilers bursting. This set a limit to which height water could be pushed up by steam. Savery had proposed to employ his devices in stages, but it was impractical to have a more than one Savery fire engine deployed in the same shaft of a mine.

The advantage of the Newcomen engine was that it could operate a chain of mechanical pumps, which could pump water in stages. However, this also came at a price. The design with a sturdy and heavy beam introduced mechanical losses and also each pump added losses. John Farey describes a Newcomen machine that produced 8.03 HP at the piston (indicated power) but the effective power to raise water from a depth of 54 feet was only 2.67 HP [3]. Machine and pumps together introduced losses of 67%. Therefore, sometimes it is said that the Newcomen steam engine was less effective than a Savery engine. This is obviously only true, (see losses by cooling a cylinder from the outside) if the Savery pump used internal condensation that was first introduced to the Newcomen engine. As Newcomen and Savery worked together, this invention of Newcomen probably at some stage will have been introduced also to Savery's pump.

Newcomen was assisted by John Calley, also spelt John Cawley, a plumber and glass-blower. We do not know what were the contributions of Calley but it was hazard a guess that Newcomen supplied the brains and Calley most of the technical skill [4]. Newcomen and Calley were later described as amateurs which after a great deal of laborious attempts, eventually succeeded in getting the engine to run, but because they lacked the necessary mathematicians or philosophers (=scientific) knowledge to calculate the powers and proportion the parts, they were incredibly lucky to find what they were looking for by accident [5]. This in no way lessens their merits. European patent laws does not require that an inventor intellectually understands his inventions or can explain the underlying physical laws correctly. The only requirement is that an inventor describes his invention so that anyone can rebuild it in a reasonable time.

Novelty of Newcomen's engine

It is frequently asserted that Newcomen's creation was merely the assembly of preexisting components. For instance, Guericke, Papin, and others had used cylinders and pistons; the pump bucket and handle were also well known; the boiler and setting were essentially just large copper brewer's kettles; and the layer of water on the piston to act as packing was a novelty but not a strikingly original idea. [7] However, most inventions combine already existing things. A new technical effect that either accomplishes something previously unknown or at the very least increases the effectiveness of something already known to such an extent that it appeals to a wider range of consumers is created when such a combination is discovered. The commercial success of an invention is occasionally cited as evidence for its inventive step.

But the source above admitted that the jet of water to condense the steam inside the cylinder was a new and important invention [6]. From a patent law of view, novelty is absolute, i.e. it does not depend if the inventor knew the prior art or independently had his idea. However, it seems to be unlikely that an ironmonger in a provincial town knew of what was going on in the scientific world of London [8].

Sources like these always overlooked the importance of the beam that was mounted by trunnions to transfer the up- and down motion to a revers down-and up-motion. Another crucial role played the counterweight.

An interesting aspect was that Papin stated that he could not purchase a cylinder and piston that would be manufactured sufficiently accurate to implement his invention. Newcomen obviously had a similar problem. To get a cylinder of any greater diameter than about 7 inch, the size that was then ordinarily made for pumps, was a difficulty, and to get it bored truly cylindrical was beyond the capacity of the pump-makers and gun founders of the day, who alone could undertake such work. It seems that Newcomen had to be content with a cast brass cylinder labouriously rubbed smooth on the inside with sand and elbow grease. The piston consequently could only be a rough fit in the cylinder, and to meet the difficulty of making it tight, packing had to be devised, a problem that roved a perennial one for engineers.[9]

Such a remark would get a patent attorney excited it shows there was a technical problem that was solved by the inventor, which is an indication that there might be something novel and inventive to claim in a patent application. And indeed the source continuous: Newcomen solved the problem for his own engine by adopting a leather flap around the edge of the piston, with water on the top [of the piston] to seal the leather. [10]

If Newcomen would have been allowed to file patents that improved existing patents there would have been plenty subject matter.

The novelty of Newcomen's construction consists in condensing the steam below an air-tight piston in a cylindrical vessel having an open top. [6] The steam is admitted into the part of the vessel below the piston. Initially, the steam was condensed by spraying cold water on the cylinder's exterior, but it quickly became clear that injecting cold water into the inside of the cylinder would be more efficient and result in faster speeds.

These comments demonstrate that individuals who are untrained in patent law use the term novelty; when they sometimes mean originality. Modern patent law has a clear definition of novelty, whereas "originality" or "inventiveness" of an invention, called “inventive step” in European Patent Law, is considered separate.

The novelty of an invention is evaluated first because, for novelty, we essentially compare the invention's technical features with only one piece of prior art. Due to the fact that the examination of inventive step becomes obsolete in the absence of novelty, this easier assessment (=novelty) is performed first.

Novelty: Article 54 European Patent Convention

  1. An invention shall be considered to be new if it does not form part of the state of the art.

  2. The state of the art shall be held to comprise everything made available to the public by means of a written or oral description, by use, or in any other way, before the date of filing of the European patent application.
  3. ...
  4. ...
  5. ...

source: Article 54 EPC

Accordingly an invention is only new if its technical features have not been made public prior to the filing date of the European patent application by means of a written or oral description, by use, or in any other manner." Novelty is absolute, ie. there are no limitations of any kind regarding the geographic area, language, age, or manner in which the relevant material was made available to the public. A written description, or document, is deemed to have been made available to the public if, as of the relevant date, it was feasible for members of the public to learn what was included within it and there was no bar of confidentiality preventing the use or distribution of such information. (Guidelines for the Examination of European Patents). As always, there may be other special circumstances that affect novelty. If you are in doubt it would be wise to consult a patent attorney.

Detailed description of the Newcomen engine

In the drawing below a boiler B with its furnace produces steam. With the use of a small steam pipe S a fluid communication is established between the boiler B and the bottom of the cylinder C. A plate p closes up the lower aperture of this pipe S. This plate p, known as the regulator or steam cock, rotates horizontally on an axis that goes through the top of the boiler. It is operated by a handle to open or close the fluid communication between the boiler B and the part of the cylinder C below the piston P.

A packing with a circular edge made of soft rope that is thoroughly packed with tallow to decrease friction is used to secure the piston P to the cylinder and make it airtight. The upper surface of the packing is kept wet to make the piston P steamtight. The working beam, which spins the gudgeon G, is linked to the piston P by a rod A that is hung by a chain from the top extremity D of the lever's arched head.

At the opposite end, this beam bears a similar arched head E for the pump rod H that draws water from the mine. When the water is drawn from a depth where the steam piston P is too heavy for this purpose, counterpoise weights l must be added to the pump rod H until the piston will rise in the steam cylinder at the proper speed.

An injection cistern L, which receives water from a forcing pump R, is located at a certain height above the top of the cylinder. From here, an injection pipe M descends until it reaches N, where it terminates in one or more tiny holes after entering the cylinder through its bottom. An injection cock, which has a handle attached to it, is inserted into the injection pipe M for interrupting the flow of the water from the injection cistern L into the cylinder C. A snifting valve V, so named because the air blowing thorugh makes a noise like a man snifting with a cold [, that turns upward has a little dish around it to store water to maintain it airtight.

Also, a pipe Q emerges from the bottom of the cylinder. This pipe is known as the eduction pipe and has its lower end submerged in a water cistern U known as the hot well. The lower end of the eduction pipe Q, which is in the cistern U, allowing the condensed water to run off by gravity on readmission of the steam. The eduction pipe is turned upward and is covered with a valve v which prevents water running back when the vacuum is reformed. The boiler has a safety valve T to control the strength of the steam, but it is only loaded to a maximum of one or two pounds per square inch (0.07-0.14 atm). It is manufactured and operated in the same way as in a Savery's engine. We note that the pressure of the boiler is lower than in a Savery engine and thus avoids boiler explosions.

The mechanism of functioning is now explained. Close the regulator or steam valve after allowing the piston to descend all the way to the bottom of the steam cylinder. The atmosphere's pressure will then keep the piston there. Add heat to the boiler until steam starts to escape from the safety valve; at that point, open the steam regulator and the piston will rise as a result of the combined action of the steam's strength and the extra weight on the other end of the beam. Close the regulator p when the piston P reaches the top of the cylinder C, then turn the injection cock O to let in a jet of cold water that condenses the steam inside the cylinder C and creates a partial vacuum. The piston P then descends through the pressure of the atmosphere, pumping water up from the mine using the pump rod H. Air introduced into the cylinder by the steam and the injection water is forced out of the snifting valve V by the force of the descending piston P. Finally, the injection water exits at the eduction pipe Q. The process of raising water is thus accomplished by repeatedly admitting steam and injecting water.

Before a young lad by the name of Humphrey Potter [12] came up with a means to fasten strings and catches to the working beam so that the machine's motions could open and close the valves, these activities were carried out by hand. The engine then moved one step closer to being a self-regulating device when more permanent appendages were added to serve the goal. It was called the Atmospheric Engine when it was in this straightforward and effective stage. Around 1712, the Newcomen steam engine was refined to this level, and such engines were erected in various places in England.



Automation of continuous motion

Desanguliers second volume of his book "A Course of Experimental Philosophy," which was published in 1744, a little over 30 years after the first engines were installed, appears to be the first longer description of the Newcomen steam engine. Desanguliers was a practical person as well. For a Newcomen engine, he created a safety valve, for instance. How much first-hand experience he had with the Newcomen steam engine is unclear, though. Desanguliers hardly ever cites his sources, as was customary at the time. He appears to be the major source of inspiration for other publications, which makes them equally unreliable. Despite his academic and engineering credentials, the descriptions in his book are excessively wordy and unconcise, as it seems to be customary at the time. Hence, using mostly the copper plates No. 37 and 38 in Desanguliers book as a guide, I created from scratch a description of the valve gear of the Newcomen engine in the manner of a patent application.

The philosopher John Theophilus Desagulier (12 March 1683 – 29 February 1744) attributed to his friend Henry Beighton the perfection of the controls of the Newcomen engine. Desaguliers describes a steam engine of the type Newcomen that Henry Beighton had constructed some years later in Newcastle on Tyne in 1718. Beighton removed all of the catches, leaving the beam itself to supply everything much more effectively [13]. This is done by fixing another arch to the great beam from which by a chain hangs a perpendicular plug frame Q, also called plug ord or plug tree. This plug frame Q having a slit in it, and several pins, gives motion to several levers, which open and shut the regulator (valve plate for admitting the steam to the cylinder) and Injection-cock at proper times.

Such a device to control input valve, the injection valve, and if present, an exhaust valve, is later called a valve gear.

If a different timing was required, control pins could be inserted in the multiple holes of such a plug frame Q and moved to a different location with ease. The plug frame Q in the steam engine built in Newcastle upon Tyne has four control pins. The opening of the regulator valve is controlled by a first control pin p that is inserted into the side of the plug frame Q opposite the viewer. The closing of the regulator valve is controlled by a second pin that is positioned between the slit of the plug frame Q. The third and fourth control pins, r and s, positioned at the side of the plug frame Q that is facing the viewer, controlling the injector valve's opening and closing.

The regulator RSYZ is composed of a circular lid R that is installed over the boiler's top opening and below the working cylinder. A throat pipe S, attached to the upper side of the lid R, provides a fluid connection between the boiler and the cylinder. A  valve plate Y is pivotally mounted with a square shank z to a pivot arrangement v w x below the throat pipe S. The pivot arrangement vwx comprises a square cone v, with a hollow inside that is also a square cone through which the square shank z form-fits and passes through from a side below the lid R to a side above the lid R. Thus the square cone v and the square shank z share a same pivot axis, which is directed vertically upright and perpendicular to the valve plate Y. Compared to a 4 inch diameter cock-valve, which is of a similar size, this regulator valve's construction only caused 1⁄10 of the friction. [Desanguliers].

A regulator spanner PQ has an end with a square opening and an arm that is split in its middle in two branches for receiving a flat end O of a forked rod MON between the two branches. The branches are fitted with several through holes, allowing to pass a fastening pin q through these through holes and a corresponding hole of the flat end O of the forked rod MON. The square shaped closed end P of a regulator spanner PQ engages the squared cone v of the regulators pivot arrangement vwx with its closed end P. When the forked rod MON pushes in the direction of the regulator, the spanner PQ pivots the plate Y anti-clockwise into the opened position opening the fluid connection, allowing steam from the boiler to enter the cylinder. Conversely, when the forked rod MON pulls with the flat end O of the forked rod MON towards the plug rod, the spanner PQ pivots the plate Y clockwise and the fluid connection is interrupted, preventing steam entering the working cylinder. As there is a slight overpressure in the boiler the regulator plate  is pressed against the lower side of the throat pipe S and therefore seals the fluid connection sufficiently. 

The regulator spanner PQ is connected to a rocking mechanism by a forked rod M O N. The rocking mechanism, as will be described below in more detail, toggles between two positions and by pulling and pushing on the forked rod M O N  unlocks and shuts the regulator instantaneously. The forked rod M O N has a single end O, that is movably connected to the end of the arm Q of the regulator spanner PQ, and two fork arms M, N on its other end. The two fork arms M, N, are suspended by a stirrup I K from an arbor tree AB.

A first spanner G4 with a first squared opening G at one end of the first spanner G4 and a curved first arm 4 on its other end, a second spanner H5 with a second squared opening H at one end of the second spanner H5 and a second curved arm on its other end 5, and a three-armed spanner CDE with a third squared opening e where the three arms meet, are lined up with their square openings on an arbor tree AB. Round pegs located at the ends of the arbor tree AB allow the arbor tree AB to be mounted rotatably. As all three squared openings form are fit on the arbor tree AB, when one lever is pushed by a pin the other levers are forced to follow this movement as the pins for proper function of the valve gear are always arranged not to block the movements of the levers with one another. 

The three armed lever is known as a Y-lever because it resembles the letter "Y" when inverted. When mounted on the arbor tree AB, two arms of the Y-lever are hanging down and one arm is pointing upwards. The arm hanging down, stretching to the right (towards the plug frame Q), is called in the following the unlocking arm D and the arm hanging down, stretching to the right (towards the regulator) is called in the following the shutting arm E. The arm pointing upwards is named in the following tumbling arm C as it is carrying a weight F, called in the following a tumbling bob. The height of the tumbling bob F can be adapted by a key.

The tumbling bob's motion is constrained by a leather strap. By fastening the middle of the leather strap to the tumbling bob F the leather strap is divided into a right halve with a right end n and a left halve with a left end m. The right end  n of the leather strap is fixed right of the tumbling bob and the left end m of the the leather strap is fixed to the left of the tumbling bob F. Thus the rocking mechanism is a bistable dynamical system having two stable equilibrium states. The first stable state is when the tumbling bob is on the left side, pulling on the right halve of the leather strap, and the second stable state is when the tumbling bob is on the right side, pulling on the left halve of the leather strap. In both stable states the potential energy of the tumbling bob is zero (unless the leather strap breaks).The tumbling bob attains its maximum potential energy when it is sitting above the tumble arm, i.e. the tumble arm is vertically orientated. As soon as the tumbling bob F crosses the vertical line, its torque switches to the opposite side, causing the tumbling bob F to fall to that side. By falling, the tumbling bob's potential energy is transformed into kinematic energy, causing the arbor tree to accelerate. When the opposite leg strikes the stirrup, the linkage of the fork and the spanner opens or closes the regulator valve in a rapid action.. 

An injection cock, embodied as a stopcock, is used to interrupt the flow of water from an injection cistern into the cylinder. The plug of the cock has a narrow, long, upright hole. A squared cone serves as the plug's stem and can accommodate a toothed wheel with a corresponding square opening at its pivot axis. A third lever, commonly known as the F lever has at its pivot axis a segment of a second toothed wheel. The pivot axis of the second toothed wheel is perpendicular to the pivot axis of the first toothed wheel and arranged so that the first and the second toothed wheel engage. The first toothed wheel lays in a horizontal axis, the first pivot axis thus orientated vertically. The second toothed wheel thus is in a vertical plane. When the F lever is lifted or pulled down the first toothed wheel is rotated in the horizontal plane and turns the plug thereby opening or closing the fluid communication between the cold water cistern and the inside of the cylinder.   

Let's refer to the side of the beam that is used to drive the pump as the pump side, and the side of the beam that the piston is suspended from by a chain as the cylinder side. We define the start of a cycle as the point when the piston changes it's direction, immediately following the condensing of the steam in the cylinder. I am proposing this definition as in few cases steam engines were erected with the volume to be condensed being above the piston. However, to keep it simple, for the following description we use the geometry as depicted in the pictures.

At the beginning of a cycle the tumbling bob F hangs on the side of the beam rod and therefore the regulator valve is opened. Conversely, the injection-cock is closed. The cylinder side of the beam is in its lowest position, pulled down by the vacuum that was formed at the end of a previous cycle. 

As the regulator valve is open the pressures above and below the piston are essentialy the same. Without a pulling force on the cylinder side of the beam the counterweight force prevails and lowers the pump side of the beam. Conversely, the pin rod Q rises along with the cylinder side of the beam. The pin located in the slit of the pin rod Q is the first pin to make contact with a lever. It raises the second lever H, which in turn rotates counterclockwise the arbor tree. By being pushed out of its stable position, the tumbling bob F accelerates the rotation of the arbor tree once it has moved from the rod beam side to the cylinder side. As a result, the  control leg D of the Y-lever CDE that is on the cylinder side is pushed by the stirrup L toward the pin rod Q. When the forked lever is abruptly pulled by the stirrup L, it pulls abruptly at the regulator lever Q, closing the regulator valve instantaneously and interrupting the steam flow from the boiler to enter the cylinder.

The drawing on the right illustrates the situation when the thumbling bob F has crossed the vertical line and is beginning to fall in a circular motion toward the regulator side just before the leg E engages with the stirrup L. 

Once the next pin comes into contact with the cock lever and opens the injection cock, the cylinder side of the beam is still rising.e cylinder and starts to condense the steam. As a result an increasing vacuum is created in the cylinder. As a result, the air pressure experiences no counterpressure and pushes the piston downward, thereby lifting the counterweight and the water in the pump.

A pulley on the first pin pulls the first lever down as the pin rod Q descends, forcing the arbor tree AB to rotate in a clockwise direction and shifting the tumbling bob from its stable position to the unstable vertical position. The lever leg D pushes the stirrup L toward the regulator and instantly closes the regulator valve once the tumbling bob F has left the vertical position and is falling downward in a circular route toward the pin rod Q.  This completes a cycle and a new cycle can begin.

What is the right speed?

Newcomen and all the other people who initially built "fire engines" appear to have tweaked their engines until they were running while being ignorant of the fundamentals. They appear to have neglected to recognize that power is defined as work per unit of time and set up their engines to deliver the most lifting power possible instead of optimizing the power delivered over a given time. When Smeaton optimized already installed Newcomen engines his modifications increased the engine speed by little more than 50%. An atmospheric engine can be made to run faster by preventing the condensation process from completing, for instance by opening the regulator valve earlier. As a result, less work is produced per stroke the earlier the condensation process is stopped. The increased speed, however, initially outweighs this loss of work.

Due to the lack of performance information for atmospheric engines operating at different speeds, or strokes per minute, I developed a small model based on the hypothesis that, after a certain point, the amount of work produced by each stroke decreases exponentially. I further assumed that the maximum power for a Newcomen engine operating at 8 strokes per minute is attained at roughly twice this speed. As a reference point, 8 strokes per minute are used. The generated work corresponds to the maximum amount of work that can be done up to this point or at this speed, respectively. As a result, the relationship between power and strokes per minute up to this point is linear. The power produced by four maximum-power strokes per minute is exactly equal to half the power produced by eight maximum-power strokes per minute. A stroke no longer reaches its full power after this point, although the increased speed still generates more work per minute. The work done each stroke now decreases faster than the increase in speed can make up for it, indicating that the maximum fraction of work per minute has finally been reached.

Due to the lack of a second or third reference point, the curve may be flatter or steeper near the maximum. The graphic does, however, accurately depict that Newcomen engines would operate more effectively at greater speeds. The roadblock in the mind of Newcomen and contemporary engine erectors was presumably to realize that, in order to enhance speed, the weight of the water column to be lifted with each pump stroke needed to be decreased in order to match the lower lifting power of an uncomplete condensation. The idea that a smaller diameter for the pump tubes would allow for improved performance was beyond the comprehension of Newcomen & Co.

Forced co-operation of Savery and Newcomen

Savery's patent covered all types of engines that used fire to lift water. Because Captain Savery already had a privilege for erecting a fire-machine, Newcomen was unable to obtain any privilege. It is unclear whether Newcomen ever attempted to submit a patent application, which was rejected or if Newcomen was aware of the Savery patent and therefore understood his request for a patent would not stand a chance.

Mårten Triewald, a Swedish engineer who came to England in 1716 and stayed there for ten years, assisted in the construction of some Newcomen engines. After his return from England, he built the first Newcomen engine in Sweden and he wrote a brief book [20] about it in 1736 that included information from his time in England.

If Mårten Triewald's interpretation of English law is accurate, the Chancellor, to whom all petitions regarding privileges were remitted at the time, took great care to ensure that neither a privilege would be granted that was in conflict with an already granted privilege that was still enforceable nor that two privileges be issued for the same thing or invention. A Royal Privilege had never been overthrown or revoked by Parliament in England. Everyone was maintained in the enjoyment of their rights, which were therefore regarded as sacred or unchangeable rights on par with the Magna Charta or the English constitution. [21]

Notwithstanding the fact that the fire engine used by Captain Savery and Mr. Newcomen's innovation were significantly different from one another, Mr. Newcomen and his co-inventor Calley saw no other way out of the troubles but to join Captain Savery and establish a Corporation. In the year 1712, Mr. Newcomen built the first fire-machine in England, which was built at Dudley Castle in Staffordshire [22].

Trievald's accounts are backed up by a note in Stephan Switzer's book about water-works: 

“I am well inform’d, that Mr. Newcomen was as early in his Invention, as Mr. Savery was in his, only the latter being nearer the Court, had obtain’d his Patent before the other knew it; on which Account Mr. Newcomen was
glad to come in as a Partner to it." [25]

Double check - Is it all about the condenser?

The use of an exterior condenser to prevent heat losses is claimed to be the principal reason for the improved performance of the Watt steam engine. It is possible to determine if this observation is pertinent. The maximum piston's pressure while raising a column of water is reported for both Watt and Newcomen engines. A maximum of 14.75 psi, or the atmospheric pressure, may be pulled by an atmospheric engine's pistons. Atmospheric engines can counteract with their pistons a maximum pressure of 14.75 psi, which is the pressure of the atmosphere. Due to the steam engine's mechanical losses and the imperfect vacuum, this maximum value is actually lower in real-world applications. According to historical reports, the working cylinder within the Newcomen engine is typically cooled down to a temperature between 140 and 160 degrees Fahrenheit (60°C-71°C). The steam pressure of the steam still present in the cylinder at 152 degrees Fahrenheit (67°C) will be close to 4 psi. [30] The ratio of 4 psi to 14.75 psi, or around 27% of atmospheric pressure, is adopted in exchange for a shorter cycle time and avoiding further heat losses if the inside of the working cylinder would be cooled down to a lower temperature. In the same example, 52% of the maximum pressure (7.8 psi) [31] is ultimately used to raise water, with the remaining 18% going toward mechanical losses (friction, acceleration losses, etc.).

Watt steam engines use typically 68% of the maximum pressure for raising water. So we can see indeed an improvement of 15% of the Watt steam engine over the Newcomen steam engine to counter mechanical losses. A part of this improvement is likely due to the improved sealing of the piston. However, we also see that from a mechanical point of view the Newcomen steam engine was already at 52%, so that indeed the most radical improvement could be achieved only by an improvement of heat losses in the steam engine and the boiler.

Historical back ground

Contrary to Watt, who's correspondence with his business partner and friends has been preserved, Newcomen doesn't appear to have any surviving historical documents of this nature. Newcomen tried to keep their knowledge of the steam engine secret and were not even allowing foreigners just to have a look at their machine. Lucky for us, a Swedish engineer, Mårten Triewald , was engaged to assist Samuel C., a son of the co-inventor with the operation of the Newman engine at a client's site. The client thought that Samuel was too young for the job and therefore Mårten Triewald was hired. Triewald stayed 10 years in England and after his return to Sweden wrote a brief book about his experiences and the first steam engine of the Newcomen type he erected in Sweden.

Recent studies [15] looking at historical documents from Newcomen's social environment reveal that he was connected to the Cornwall mining industry through family, friends, and neighbors, as well as through his occupation as an ironmonger.


[1] John Farey, A treatise on the steam engine : historical, practical, and descriptive, London 1827, page 132 available INTERNET ARCHIVE

[2] Ibid, page 133

[3] Ibid, page 132

[4] H.W. Dickinson, "A short History fo the Steam Engine", Cambridge, 1939, page 33

[5] J.T. Desaguliers, "A Course of Experimental Philosophy", London, 1744,page 533

[6] Thomas Tredgold, The Steam Engine, Vol. I,  London, 1838

[7] H.W. Dickinson, page 29/30

[8] Ibid, page 33, referring to Transaction Newcomen Society, XVII, page 6.

[9] H.W. Dickinson, page 33.

[10] Ibid.

[11] J.T. Desaguliers, "A Course of Experimental Philosophy", London, 1744, page 474

[12] J.T. Desaguliers, "A Course of Experimental Philosophy", London, 1744, page 533

[13] Ibid.

[15] James Greener, Thomas Newcomen and his Great Work, October 2015, available on ResearchGate

[20] Mårten Triewald, Mårten Triewald's Short description of the atmospheric engine: published at Stockholm, 1734, Translated from the Swedish [by Are Waerland] with foreword [by Carl Sahlin], introduction [by Rhys Jenkins] and notes [by Are Waerland]

[21] Ibid.

[22] Ibid.

[25] Switzer, Stephen (1729) ‘An introduction to a general system of hydrostaticks and hydraulicks’, page 342 available Internet Archive 

[30] John Farey, page 132

[31] John Farey, page 131