THE MOTTLAU & SVENDSON ROTARY EXPANSIVE ENGINE: 1890

Left: The Mottlau & Svendson Rotary Engine: 1890 This article, taken from a British patent, shows a rotary engine concept that would have been viewed as completely unworkable a hundred years earlier. The sliding tube F, through which the steam is supplied, is pressed against the rotor by a powerful spring, so that every half-turn it drops off the top edge of the rotor and smacks down on its lower portion; it is hard to see that working for very long, and as noted in other much earlier engines with the same feature, the noise while running would have been appalling Sealing is "by springs". Good luck with that. A baffling feature of this engine is the tiny exhaust outlet at J; it is much smaller than the inlet are of tube F. And why is it provided with a tap? Mottlau and Svendsen were from Copenhagen, Denmark, but obviously considered that London was the place to take out an engineering patent. From the English journal Industries 27 Nov 1890, p526

THE BROWN ROTARY EXPANSIVE ENGINE: 1891

Left: The Brown Rotary Expansive Engine: 1891 This engine was put forward by Alexander Francis Garden Brown of Swindigemuir, Ayrshire. That's Garden, not Gordon. It appeared in the journal Industries, and uniquely, full details of trials run on it were given. The engine was run at between 560 and 600rpm and yielded between 19 and 22 BHP. The engine was built by Messr John Lang & Sons of Johnstone, ansd it was at their works that the trials were conducted. The trials were conducted by Professor Jamieson of the Glasgow and West of Scotland Technical College. He said: " ..the gross consumption of steam is only 27.2 lb per IHP-hour, results which surpass not only any other rotary engine, but equal those of the very best simple expansion, fast speed, no-condensing engines with which I am acquainted or have seen recorded." This seems like a pretty good report; perhaps it was lack of durability that doomed the Brown engine, for so far as is currently known it was never heard of again, except at the patent office. From Industries 17 July 1891, p65

THE MURCH ENGINE: 1891

Left: Murch rotary steam engine : 1891 Another rare example of a rotary engine that was actually built and has survived for us to admire. This engine was invented by William Henry Murch of Southampton, England. British patent No 10,404 was issued in June 1891. This example is supposed to have been built by Terry & Wilsher of Southampton, probably as a demonstration model. The engine was for sale on Ebay recently; it was bought for £450 in October of 2019. See here. Its condition was stated as 'used'.

Left: Murch rotary steam engine : 1891 The Ebay ad gave the dimensions of the cylinder as width 6", outside diameter 5", height 7". The base was stated to be 5" wide, and the weight of the engine 2.6 kg. From the small size it is obviously a model rather than a practical engine for doing a job of work.

Left: Murch rotary steam engine patent: 1891 For once the operation of the engine is very clear just from the patent drawings and it is not necessary to furrow the brow over patent text, which can be less than lucid. This is another case of a rotary piston (Fig 7, 8) that goes round inside a cylinder, with a swinging abutment (Fig 14) that gets out of the way just in time to let the piston pass it. How anybody expected this sort of process to be leak-free is beyond me. The swinging abutment is moved by a cam E (Fig 9) mounted on the drive-shaft. The cam-follower F drives a bell-crank F2 that oscillates a disc G6. (see Fig 4) that From US patent 495,357 granted April 1893

THE CLELAND ENGINE: 1891

Left: Cleland rotary engine patent: 1891 This engine was patented by Alexander Cleland, who lived in the colony of Victoria, later part of Australia. (The Commonwealth of Australia as a dominion of the British Empire was not established until 1901) There is an eccentric rotor b which rotates around the crankshaft, bearing a vane (described in the text as a 'blade or abutment') that oscillates in the teardrop-shaped cavity e. Sealing looks to be impossible. The exhaust port f is just above this cavity. The steam inlet port s feeds into the centre of the rotor; see the extreme left of Fig 2. Apart from the patent, the Cleland engine is unknown to Google, and it clearly failed to thrive. US patent 455,863 granted 14 July 1891

Left: Article on Cleland rotary engine The drawings here appear to be based on the US patent, but the parts have been re-lettered in some cases. Here we have a vane L which appears to oscillate in the space M. There are no obvious bearing surfaces to guide the vane. Note the part about adjusting a set-screw to maintain contact between the piston and the cylinder; clearly that would be critical to attaining any sort of sealing. Alarm bells are ringing... The Melbourne mentioned is presumably the one in Australia. There was some doubt about the date of this engine. The report here gives a patent date of 1881 at the end, but it was published in 1891. Seems to be a typographical error. The US patent is dated 1891 which seems to confirm the later date as correct. The patent number given is 8,289 which means it must be a British patent (which started their numbering from 1 every year up until 1915) that is referred to. By this date US patents had reached the 300,000's. From Industries 23 Oct 1891

THE STOCKER ENGINE: 1891

Left: The Stocker rotary engine; 1891 This pleasingly straightforward engine was patented by James M Stocker of Atlanta, Georgia. One-third was assigned to Ziba O Stocker, of San Antonio, Texas, who was presumably his brother. A rotor with two sliding vanes was mounted axially in a cylinder, with the shaped piece K making the cylinder effectively eccentric. Steam inlet was via the oscillating valve C and the inlet port a, with exhaust leaving via the port at a'. Sealing depends on what is essentially a line contact at k, as well as the sealing at the tips of the vanes. The inlet valve was driven from an eccentric on the output shaft. The engine was not reversible. The patent text is mostly devoted to sealing, which shows that James Stocker at least knew what he was up against. The name Stocker was heard of in 1872, but the drawing, from Mechanical Movements, Devices and Appliances by Hiscox, (1899) has nothing in common with this engine, and no patent corresponding to it has so far been found. Otherwise James Stocker is unknown to Google, and clearly his engine failed to thrive. From US patent 459,381 granted 8 September 1891

Left: The Stocker rotary engine; 1891 This shows the outside of the Stocker engine, with the eccentric on the output shaft that oscillated the steam inlet valve. It is not known why the eccentric was constructed in this odd offset manner. From US patent 459,381 granted 8 September 1891

Left: The Stocker rotary engine; 1891 The internals seen from above. The details of d1, d2 g, g3, etc are relevant to the sealing methods described in the patent text. From US patent 459,381 granted 8 September 1891

THE BEARD ENGINE: 1892

Left: The Beard rotary engine; 1895 Andrew Beard was given a patent for this rotary engine in 1892. There are two rotors C C facing each other so that the steam pressure on them is balanced and there is no axial thrust on the shaft. There are abutments or 'steam stops' Q Q which fit in annular grooves in the rotors. Each rotor is fitted with two pistons T T which by cam action on the grooves rotate the rotors. The patent text then says: "On the upper half of the revolution the cams withdraw the pistons TT from the outer walls of the heads to let the exhaust steam escape and to allow the pistons to pass the steam-abutments Q Q" This is a familiar theme in rotary steam engines; mechanical parts which almost magically get out of the way in the nick of time, and manage to do it without any steam leakage. It seems enough evidence for us to conclude that Beard's engine was unlikely to have worked successfully. The engine was reversible by means of the valve-chest on top of the engine. Beard also got an earlier patent for a rotary steam engine; US 433,847 was filed and granted in 1890. Rotary engine drawing from US patent 478,271 (5 July 1892)

Left: The only known image of Andrew Beard Andrew Jackson Beard (and to a much lesser extent his rotary engine) are, like Margaret Knight, Iconic Inventors in the annals of American history; Beard because he was an African-American who had spent the first 15 years of his life as a slave in Alambama in the American South, and Knight because she was a woman. Beard's real claim to fame is the invention of an automatic railroad car coupler, the patents for which gained him a considerable amount of money. There is more biographical information on Andrew Beard here. It says that his rotary engine "...saw limited use" but no hard evidence has been found that it was ever built. Beard's railroad coupler patents were US 594,059, (23 Nov 1897) and US 624,901 (16 May 1899)

THE HENDERSON ENGINE: 1895

Left: The Henderson rotary engine; 1895 This engine was patented by Robert L Henderson of Texas, USA. It is unknown to Google apart from the patent, and so apparently failed to thrive. From US patent 536,348 dated 26 March 1895

Left: The Henderson rotary engine; 1895 Inside the lower casing is a pawl-shaped rotor 6 with a swinging abutment plate 10 held against it by an external spring. The movement up and down of the abutment plate operates the inlet/exhaust valve 26. Note that the engine is inherently non-reversible. The swinging abutment makes a line contact with the rotor and so will be hard to seal. The rotor makes an area contact with the inside of the cylinder, but it is a small area. From US patent 536,348 dated 26 March 1895

THE MORSE ENGINE: 1896

Left: The Morse triple-expansion rotary engine; 1896 There are several compound (double-expansion) rotary steam engines in the Museum, such as this anonymous compound engine and the Filtz engine just below, but I think this is the only triple-expansion engine. As you can see, at least one was actually built. At the top is the pipe for incoming steam; below a fly-ball governor driven by belt from the output shaft can just about be discerned in this rather low-quality image. Three rotor casings on top of each other can clearly be seen. US patent 562,843 was issued to Henry T Morse, of Boston, Mass, in June 1896; it is a lengthy document with six pages of text. It was assigned to The Morse Rotary Engine company, an outfit that appears to be unknown to Google but which seems to have had the cash to get a quite complicated prototype built. This patent was referenced in US patent 3,578,890 in 1971, a more recent attempt to improve rotary steam engines. The name Henry T Morse is also unknown to Google. This appears to be a prototype built by the Pratt & Whitney Machine Tool Company. (Not to be confused with the Pratt & Whitney Aircraft Company) They were a primarily a machine-tool company, but also built engineering prototypes, of which the most famous is the Paige typesetting machine, in 1889 and 1890; the prolonged and unsuccessful development of this machine cost Mark Twain at least one fortune. From the Pratt & Whitney History Book, Part 2

Left: The Morse triple-expansion rotary engine; 1896 The internals revealed. Fairly standard stuff but with three pairs of rotors in series, all geared together, to give triple-expansion. From US patent 562,843

THE FILTZ ENGINE: 1897

According to Nature, this engine was invented some years before its publication in 1897. It also said that a "fairly large number" had been constructed and put into use.

Left: The Filtz compound rotary engine; 1897 A single-cylinder version of the engine weighed 28 kg and developed 5 HP at 1200 rpm; steam pressure was described as 6 kg, presumably meaning 6 kg/cm2 which is 85 psi. The "diameter" was given as 94 mm; presumably this was the diameter of the internal rotor as it seems too small for an outside dimension. The compound version shown here, running at the same inlet pressure with 350 and 600 mm diameter cylinders, was stated to give 40 HP at 300 rpm, using 9 to 10 kg of steam per horse-power when working with a condenser. It had a volume of less than one cubic metre and weighed 1200 kg, presumably without the condenser. (That's over a ton, and seems very heavy for a 40 HP engine) In the compound design, the two rotor assemblies were staggered in angular alignment to smooth out the torque delivery. A version with a nominal output of 70 hp was said to actually be capable of 100 hp. From the French journal Nature 1897/1

Left: The Filtz compound rotary engine; 1897. The operation of this engine is not very clear from the text and drawings, but it goes something like this: The engine shaft M carries two rotors which have faces in the form of helicoidal ramps. They are divided from each other by the fixed partition P. Two vanes A and B slide in and out through P as the helicoidal ramps turn with the shaft, forming steam spaces that expand and contract. Steam moves in and out of these spaces through ports in the helicoidal faces, exerting pressure of which one component is in the direction to cause rotation. From the French journal Nature 1897/1

This construction, with the sliding vanes bearing against a ramp of constant slope, would seem to offer at least the possibility of an area seal against the ramp rather than a line contact.

Left: The Filtz compound rotary engine animated. This animation by Bill Todd is based on the 1896 patent. Bill says: "The outer part of the rotor has been removed and the front ramp is transparent to show the internals better. The input and exhaust chambers are the two semi-circular cut-outs in the ramps. The brass bit at 12o'clock is a seal to stop leakage directly between inlet and exhaust ports. I've angled the edges of the blades as Filtz's square edge blades would have jammed; the varying angle between blade and ramp means only a line contact is possible. (Filtz's blades were two parts, sprung apart to 'seal' against the ramps) Another brilliant animation by Bill Todd

The steam expansion ratio was calculated by M R Guyoot-Sionnest, the naval construction engineer to be 1.5, which persumably means admission cutoff at 66%. Nature pointed out "this corresponds to a mediocre utilisation of the steam"

THE UNBEHEND ENGINE: 1898

Left: The Unbehend rotary engine; 1898. This rotary engine was patented by Mr Jacob J Unbehend in June 1898; he was awarded US patent No 606,606. The engine has a central rotor B from which protrude gear teeth; these are morticed in place in the rotor to allow ease of replacement. On each side of it are rotary admission valves C which are synchronised with the main rotor by external spur gears. Steam enters through the centre of these valves and passes into the working chamber through their radial passages, and pushes round the main rotor, both at top and bottom to "maintain equilibrium" and presumably cancel out side-thrust on the main rotor bearings. Exhaust was via passages f and valves g. The position of these valves, and the operation of the admission valves, could be changed by a single lever to reverse the engine.

There seems little scope for the expansive use of steam, and there are no means shown for sealing the tips of the gear-teeth to the inside of the casing; this suggests that acceptably economical operation would have been impossible. However, the patent drawings have a practical look about them which suggests that this engine might have been actually built, if only as a prototype.

THE WILLERTON & SHORTLIFF ENGINE: 1898

Left: The Willerton & Shortliff rotary engine; 1898 These drawings appeared in Scientific American in 1898. According to the Annual Report of the Commissioner of Patents for April-June 1899, they were awarded US patent 604,601 for a rotary engine on 24 May 1899, but Google patents does not seem to have it, nor does USPTO, so heaven know's what's going on. T Shortliff and W Willerton of Blackfoot, Montana, are referenced in the 1898-1899 Automotor Index, leading to a report of British patent application 7,201 for 1898, on p321 of Automotor for March 1899; so far this is the only trace of them.

THE KESSLER ENGINE: 1898

Left: The Kessler rotary engine; 1898 This design was put forward by Martin Kessler of Gilead, Indiana. (Gilead? Does Margaret Atwood know about this?) It is another engine based on a rotor with sliding vanes inside an eccentric cylinder. From US patent 602,334 granted April 1898

Left: The Kessler rotary engine; 1898 This gives some details of the intended sealing method for the vanes. Helical springs push the vanes outward axially, to butt against the ends of the cylinder, while the bent-looking springs (what is the right term here?) push the vanes outward radially. Note the hefty flywheel. From US patent 602,334 granted April 1898

THE TAYLOR ENGINE: 1899

Left: The Taylor rotary engine; 1899 This rotary engine was patented by Mr C G Taylor of Kansas, USA. It is of the sliding-door type. The spring-loaded door seen at the centre of drawing 2, with its little ant-friction roller, is supposed to be pushed out of the way of the spring-loaded vane carried on the rotor by a cam on said rotor. This will bring in the usual problems of door timing and leakage. Steam admission was controlled by rotary valves operated by a small eccentric, as seen in drawing 1. Speed could (in theory, at least) be controlled by varying the cut-off; the thin vertical rod in drawing 1 connected to a governor. The small lever apparently reversed the engine by interchanging the inlet and exhaust functions. From the size of the pipework, it can be deduced that two outer chambers in the valve chest were for inlet, and the central chamber was the exhaust passage. The large central valve appears to allow exhaust to be taken from either side for reversing. However the arrangement of the inlet valves is a bit mysterious- there seem to be two in parallel on each side; I suspect the drawing may be wrong. From The English Mechanic and World of Science, 6 Jan 1899, p486.

Left: Side view of the Taylor rotary engine. The engine consisted of two rotors, presumably to reduce torque variations during a rotation. The cams that operate the vertical sliding-doors can be seen just inside the casing at the ends of the double rotor structure. On the left rotor the vane is at the bottom and the vertical door is closed; at right the vane is at the top and the door has been lifted to let it pass. No division between the rotor compartments is shown, which must be wrong. From The English Mechanic and World of Science, 6 Jan 1899, p486.

Left: The Taylor rotary engine; 1899. Description from The English Mechanic and World of Science for 6 Jan 1899, p486. It is impossible to believe that this engine could ever have worked satisfactorily.

THE HAY & DEPUY ENGINE: 1899

Left: The Hay and Depuy rotary engine; 1899. James T Hay and Gilbert L Depuy came from Garland, Texas. The operation of their engine is fairly clear from the diagram; there are two vanes that slide in and out under the control of cam grooves in the end of the cylinder; it is not easy to see here but there are swivelling shoes on the ends of the vanes. Steam is admitted via ports in the rotary valve shown in the centre of the picture; how it gets out again is not clear, but the large vertical pipe shown on the right is presumably for the exhaust. From The English Mechanic and World of Science, Sept 23 1899. The original report appears to have come from Scientific American

The lever-operated slide-valve arrangement on top of the cylinder is for reversing. The brief article describing the engine makes some interesting remarks on the sealing problem: "In order to prevent leakage of steam, the inner faces of the cylinder-heads, the interior of the cut-off valve casing, and the cut-off valve, are formed with grooves adapted to receive the water of condensation. As they fill with water, they form a packing for preventing the escape of steam."

I really have no idea whether that would work or not, but I suspect not.

THE TOENNES ENGINE: 1899

Left: The Toennes rotary engine; 1899. Patented by Richard Toennes of Boonville, Missouri, this engine was designed to use steam expansively. The rotor was mounted eccentrically and the spring loaded vane had a rocking shoe on the rubbing end. There were two ports, used interchangeably for inlet and exhaust, the direction of rotation being selected by the reversing valve plate at 3 in the picture. This plate was shifted by the lever shown at 1. The main valve plate was moved back and forth by an eccentric on the main shaft. Steam could be cut off at 1/4, 1/2, or 3/4 of the piston 'stroke'. Lubrication was fed in at three places only. Fig 1 shows the engine partly cut away to display the cutoff mechanism. Fig 2 is a section, and Fig 3 shows the reversing valve plate. From The English Mechanic and World of Science, Oct 13 1899.

THE SEYMOUR ENGINE: 1899

Left: The Seymour rotary engine: 1899 This is an article that appeared in Locomotive Engineering for Feb 1899. The author was, as usual, unoptimistic about the utility of rotary engines and considered the Seymour engine unlikely to be an exception. Time for a patent search, and the first hit for Mr Seymour is US patent 62,586, 21 Mar 1899: J. M. SEYMOUR, Jr. "ROTARY IMPACT OR TURBINE STEAM ENGINE" That however is definitely a turbine of the Pelton type, and the article is clear that we are looking for a rotary engine. Next up is US patent 622,718 Patented Apr. 1, 1899: ELISHA SEYMOUR of Chicago: "ROTARY ENGINE". This looks like the goods; no other Seymour rotary engine patents have been found so far. It certainly fits the description of "rather an expensive construction", in that the patent drawings are rather complicated; see below.

THE THORNMEYER ENGINE: 1899

Left: The Thornmeyer rotary engine: 1899 I'll just quote from the patent abstract: Annular-chamber type. A rotary steam engine with sliding vanes is shown in section in Fig. 1. The shaft c carries a disc d in which slide three vanes e, pressed outwards by spiral springs or otherwise. The steam pipe g supplies steam, through passages h in the casing to suitably operated valves l, through which the steam is admitted to the steam chambers f. The steam chambers are made with an annular portion into which the steam passes without expansion, and with a crescent-shaped portion, in which the steam expands and in which a correspondingly increased area of the vane is exposed to the steam. The exhaust passages m lead from the ends of the crescent-shaped ends of the steam chambers. Quite apart from any sealing issues, this does not look like a practical design. The steam passages are tiny, the rotary (?) valves are tiny, and even the incoming steam pipe looks ridiculously small for the job. From British patent 22,137 in 1899. British patents were numbered from 1 in each year up to 1915. Hans Thornmeyer was a Prussian. He also took out US patent 651,616 in 1899, for an identical engine design. Other British patents were "Improvements in compound internal combustion engines" GB 252,736-A dated December 16, 1926, and "Propelling ships and boats" GB 389,711-A dated March 23, 1933. This was a paddle wheel arrangement. Hans Thornmeyer was at this time living at 82, Martin Lutherstrasse, Berlin. Probably time to move out... There was also an earlier French turbine patent: "Turbine à vapeur" FR332849-A dated November 9, 1903.

THE JAMES ENGINE: 1900

Left: The James rotary engine: 1900 This engine was patented by William James of Phoenix, Arizona. According to the full text below, it is a rare example of a compound rotary engine, but this is contradicted by the picture here which shows two engines of identical size connected to the same steam supply coming in from the top. The text states that two engines were connected together out-of-phase to avoid dead-centre problems. There is no full drawing of the internals, but the details in Figs 2 and 3 make it clear that a cylindrical rotor inside a cylindrical casing carried a small ramp which knocked aside a swinging door A as it passed. B is a dash-pot composed of a plug moving in and out of a hole which was intended to reduce the violent shocks on the door when it swung in to contact the rotor. D is a rotary admission valve driven by gearing, intended to give expansive working; no sealing details are visible. Steam reached the rotor via a narrow port running through the swinging door, but confusingly this is drawn differently in Figs 2 and 3; Fig 2 is probably the correct arrangement. From The English Mechanic and World of Science, Jan 12 1900, p489.

The exhaust arrangements are not shown; presumably the joined pipes emerging from the lower parts of the valve chests carry away the exhaust steam, which goes off to the left. The exhaust piping is not much bigger in diameter than the inlet piping, so one wonders just how much expansion was going on. Note the two little drainage cocks at the bottom of the valve chests.

Left: The James rotary engine: 1900. The text of the article in The English Mechanic. What immediately stands out with this engine (apart from the usual impractibility of having swing doors or abutments banging about inside it) is the very small area of the ramp face on which the steam pressure acts. Almost all the volume of the engine does nothing at all; even if everything else worked the power-to-weight ratio would have been laughable. This is a common characteristic of swing-door and revolving-door engines, such as The Eve Engine (1825), but this is the worst example discovered so far. It is not currently known if this engine was actually built and tested. From The English Mechanic and World of Science, Jan 12 1900, p489.

THE DEARING ENGINE: 1900

Left: The Dearing rotary steam engine; elevation and cross-section: 1900 The Dearing engine is an endearing engine, given its very elegant patent drawings. It was patented in June 1900 by David M Dearing of Denver, Colorado. Here there are two engines coupled together, with ancillary machinery between them. Each engine has two eccentrics 28. From US patent 652,168 of June 1900. The Dearing rotary steam engine is unknown to Google.

Left: The Dearing rotary steam engine cross-section: 1900 This is how it works. There is an eccentric rotor, having a line seal with the inside of the cylinder. The 'cylinder head' is moved up and down on the rotor by means of the eccentrics 28, and carries a vertical divider 9 which is supposed to seal with the rotor. This very like the much earlier Yule engine of 1836. Steam inlet is controlled by the rotary valves 15,15a, driven by spur gearing from the main shaft; the engine is reversible and its direction depends on which of these valves is used. The exhaust ports are at 17,17a Note the centrifugal governor, which is driven from the rotary valve gearing by a belt. The smaller valves 16, 16a are operated by the governor to regulate the speed. As always, I wonder what happens if the belt breaks... From US patent 652,168 of June 1900.

Left: The Dearing rotary steam engine cross-section: 1900 This shows the drive to the rotary valves via gears 22 and the governor via wheel 20a. From US patent 652,168 of June 1900.

Left: The Dearing rotary steam engine cross-section: 1900 This shows how the governor controls the two rotary valves 16, 16a valves via the toothed sectors 35, 36. We also get a better view of the eccentric 28 that moves the 'cylinder head' up and down. From US patent 652,168 of June 1900.

THE TINKHAM ENGINE: 1900

Left: The Tinkham rotary steam engine; cross-section: 1900 This design was put forward by Oliver Tinkham of Havana, Illinois. The Tinkham patent is complicated, with six sheets of diagrams and three-and-a-half pages of text. The central shaft 1 carries an eccentric rotor 6. The ring 14 divides the annular steam space of the engine into two crescent-shaped compartments; a primary compartment 12 and a secondary compartment 11. The piston 13 extends from the rotor through an opening in the ring 14 to the outer wall of the cylinder; when it is revolved in the cylinder by the steam pressure it turns the output shaft 1. There is a passage between the two compartments so that steam admitted to the primary compartment 12 behind the piston passes to the secondary compartment 11 after it has moved the piston nearly through the primary compartment and acts on the piston the second time. The secondary compartment 11 is about double the capacity of the primary compartment 12, and so the steam is intended to act in the two compartments on the principle of a compound engine. There is provision for admitting steam directly to the As usual the details are rather complicated and reference to the patent text is advised if you want to know more. Figure 4 is a piston valve that controls steam admission and reversing; the end of it can be seen just under the cylinder in Figure 3. From US patent 659,007 of October 1900

Left: The Tinkham rotary steam engine; cross-section: 1900 No rotary engine is complete without a big handle. This one appears to control the steam admission cutoff (after reading the text I'm still not sure about that) and definitely controls reversing. From US patent 659,007 of October 1900

THE CROSTON ENGINE: 1901

Left: The Croston rotary steam engine; cross-section: 1901 Thomas Croston took out US patent No 674,258 in May 1901. It was for a very complex system that actually consisted of two engines- a main rotary engine and an auxiliary governing engine; speed was controlled by varying the admission cut-off. The picture here shows a transverse section of the main engine. E and E'are the rotary inlet valves; the angular relation between them was altered by the governor to control the admission period. When cut-off valve E' lagged behind valve E it admitted steam for a longer period. Note that the spring-loaded vanes are also pressed outwards by small steam cylinders C3 and C'3; each has a pair of valves connected by a see-saw lever, that ensure that the side of the vane at the highest steam pressure is connected to the cylinder. A seal B presses against the top of the rotor. The rotary exhaust valves are at J and J', and steam leaves through the port at the bottom the casing. The narrow and winding steam passages do not look as though they would encourage steam flow.

THE KEMP ENGINE: 1901

Left: The Kemp rotary steam engine: 1901 Thomas Kemp of Bath puts forward a design that is at least different. A piston is working in a cylinder in the usual way, but according to the patent "there is a spiral groove in the middle of the piston". Spiral doesn't seem to be the right word as the piston would screw itself to the end of the cylinder and stay there; in fact from the drawing the groove appears to be continuous so the piston could rotate continuously as it went to and fro. The expansive use of steam appears to be possible with suitable valve-timing, and and the usual sealing difficulties are not present as the piston is sealed with conventional piston rings at each end. This info is extracted from UK patent specification, No 26,452. (1901)

THE WARREN ENGINE: 1902

The Warren rotary engine seems to have created more interest than most of its kind. It was noted in the book Modern Industrial Progress by Charles H Cochran. (pub 1904 by J P Lippincott) Here is an extract:

"...There has been selected for illustration here one of the most promising rotary engines, the invention of E C Warren, which is manufactured by the Rotary Engine Company of Philadelphia. ...Thus far the arrangement is very similar to other rotary engines, the chief feature of the Warren engine consisting in one end of the cylindrical piston being made a little smaller than the other end, to cause a slight end-thrust that tends to force the tapered wheel farther into the tapered bore of the casing, thus maintaining close joints in spite of wear on the surfaces. There is also a device for preventing an excess of end-thrust. The difficulty with most rotary engines has been that they either leaked steam or lost power because of extreme friction. Perhaps this engine or some outgrowth from it may prove more free from these than its predecessors."

Mr Cochrane then goes on to discuss steam turbines, which were well-established by this time.

Left: The Warren rotary steam engine: 1902 The Warren engine coupled to an electrical generator. It is not possible to get any idea of scale from this drawing. The exhaust steam from the engine passes into ita outer casing which communicates with the hollow baseplate. The flange connection is presumably led to a condenser. From Modern Industrial Progress

Left: Warren rotary steam engine advert After much searching the museum staff were able to track down this advertisement, which looks like the source for the engraving above. It is now clear that the round thing at the extreme right is a handwheel (presumably controlling the steam supply) which gives some idea of scale; it looks as if the engine casing is two to three feet long. It is possibly significant that efficiency is only mentioned once, almost in passing. It is a feature of this engine that any leaking steam would be hidden inside its outer casing and not obvious to the user. The National Museum of American History has trade catalogues for the Rotary Engine Company, but there does not seem to be any way to access them on-line.

Left: The Warren rotary steam engine: 1902 This is a version with two rotating rollers either side of the main rotor. Steam is admitted through the centre of this rotor and the ports in it adjacent to the two abutments fixed to the rotor. The steam expands as the rotor turns clockwise and exhausts through the passage at upper right. The rollers have notches in them to allow the abutments to pass, and are synchronised by spur gears at the end of the engine casing. The rotor has two sections which work displaced 90 degrees, presumably to give a smoother output torque. Note that the engine depends on good sealing at the line-contact between the central rotor and the two rollers. From Modern Industrial Progress

Left: The Warren rotary steam engine: 1902 The rotor, showing the two sections displaced by 90 degrees. From Modern Industrial Progress

Edward C Warren (of Providence, Rhode Island) was granted US patent No 715,221 in December 1902. It contains detailed descriptions of the way that steam pressure on the components was supposed to reduce leakage, as referred to above.

Warren took out a number of patents:

Rotary engine	US 680,510	Aug 1901
Rotary engine	US 715,221	Dec 1902
Rotary engine	US 761,799	June 1904
Rotary engine	US 798,848	Sept 1905
Internal combustion pressure generator	US 981,339	Jan 1911
Rotary engine	US 1,861,168	Sept 1928

The 'Internal combustion pressure generator' produced a mixture of hot combustion gases and steam, which drove a rotary engine coupled to an electrical generator.

Left: Three-roller version of Warren rotary steam engine: 1902 The engines of the Navette (see below) appear to have been of this type. From US patent No 715,221 of Dec 1902

Left: Compound coaxial Warren rotary steam engine: 1905 This intimidating drawing comes from Warren's 1905 patent. It shows a compound rotary engine where a complete high-pressure engine rotates inside the low-pressure engine. The entire high-pressure engine forms the rotor on which the low-pressure steam acts. The reversing valves are labelled 31 and 31a. Fig 4 from US patent No 798,848 of Sept 1905

Left: Compound coaxial Warren rotary steam engine: 1905 This shows one end of the engine casing. 40 is the reversing lever and 34 an oil supply pipe. 43 is one of the strips holding lagging onto the casing. It appears from the patent text that in reverse steam was admitted directly to the low-pressure engine, with the high-pressure engine unused; this does not seem to me a good arrangement unless running in reverse was rare, so that occasional low efficiency was acceptable. Fig 6 from US patent No 798,848 of Sept 1905

What Mr Warren was up to between 1911 and 1928 is currently unknown. He reappears in 1938:

THE BRIDGE ENGINE: 1903

Left: The Bridge rotary steam engine; cross-section: 1903 Homer E Bridge received US patent No 735,203 in August 1903. A small circular piston D went round inside an annular space a, in an anti-clockwise direction as shown by arrow x. The small rotor E kept the inlet and exhaust sides of the piston sealed from each other,and also acted as a rotary valve; it was driven by a notched wheel which was intermittently pushed round by a pin on a disc that was coaxial with the main rotor. The handle F3 appears to have varied the cut-off. Another handle attached to the valve K allowed starting, stopping, and reversing by rearranging the steam passages to the small rotor. Like the The James Engine above, it is noticeable that the piston area is very small compared with the size of the engine, and even if everything else had worked, the power-to-weight ratio would have been poor. There are however, the usual sealing problems, such as the line contact between the two rotors.

THE DAILEY ENGINE: 1903

Left: The Dailey rotary steam engine: 1903 The Dailey engine was patented in 1903 by Herbert M. Dailey of Chicago. It was announced in 1905 that the engine was going to be manufactured by the R. McDougall Co Ltd; this was later changed to a plan to licence the design to others. The company was not heard of again, and gets only one hit on Google today, so I assume it was not a success. THe Dailey Rotary Engine Co was incorporated in Chicago on 2nd Feb 1904, with a capital of $100,000. From Canadian Machinery Jan 1906

THE COOLEY ENGINE: 1903

Left: The Cooley rotary steam engine; cross-section. American, 1903 The Cooley engine has a two-lobed inner epitrochoid working in a three-lobed outer envelope; both rotate in the same direction and are geared together in the ratio 3:2. The simplified drawing to the left is clearly taken from the last Cooley patent, No. 748,348. This design is interesting because its eccentric rotor with internal gearing clearly foreshadows the Wankel engine. It is not clear from this diagram how steam enters and leaves, but the inlet and outlet ports can be seen in the second Cooley patent drawing below. This is a distinctly more sophisticated concept than most of its predecessores, but there are still line seals and the end sealing to grapple with. In 1908 the English engineer Umpleby tried to make an internal combustion version of this design, but did not get far with it. See The Umpleby Engine.

A point of note is that the inventor, John F Cooley of Suffolk county, Massachusetts, was a pupil of Reuleaux, and was hired to work on rotary piston engines in Berlin under his direction. This is interesting in the light of the very low opinion Reuleaux had of rotary engines. (NB: This info comes from Norbye and has not been confirmed so far)

Left: Animation of the Cooley rotary steam engine. Here it can be seen clearly that the inner rotor rotates about its center, but the outer envelope is mounted eccentrically. This superb animation is kindly provided by Bill Todd

Left: Engine drawing from Cooley's first patent, No 724665 of 1903. The design was covered by US patents 724,665, 724994, 725615, and 748,348, which are shown here. All these patents were in 1903, the last being dated 29 Dec 1903. As with many rotary engines, it was also patented as a pump. There was a British patent 6168 (1903); this is such a low number because until 1915 the British patent numbering system reset at the start of every year.

Left: Engine drawing from Cooley's second patent, No 724994 of 1903. The top half of the drawing shows the somewhat labyrinthine ports by which steam or some other fluid de jour entered and left the working chambers.

Left: Engine drawing from Cooley's third patent, No 725615 of 1903.

Left: Engine drawing from Cooley's fourth patent, No 748348 of 1903.

Two companies were set up to exploit this engine; the Cooley Epicycloidal Engine Development Company of Boston and of New Jersey, and the Cooley Epicycloidal Engine Company. (incorporated in New Jersey)

Left: Newspaper announcement of the formation of the Cooley Epicycloidal Engine Company. This appeared in the New York Times on Friday, March 20, 1903.

THE MARGARET KNIGHT ENGINE: 1903

Left: The Margaret Knight rotary steam engine patent: 1903 This engine is believed to be unique both in its construction and because it was designed by a woman, Margaret Eloise Knight. Knight is mostly famous for inventing the flat-bottomed paper bag, and the machinery to make it, but she took out at least four patents for rotary steam engines; this one, and also US 716,903, US 717,869 and US 758,321. The engine has a central rotor with an eccentric pin which moves three vanes swivelling in cylindrical guides. These vanes define volumes that expand and contract as the rotor turns. Steam introduced into these in turn were supposed to rotate the engine. The valves appear to have been rotary. No evidence has been found that this engine, or any of the others patented, were ever constructed. Image from US patent 720,818 for 17 Feb 1903

Left: The Margaret Knight rotary steam engine: side view Here is Bill Todd's explanation of this strange engine: "The chambers at the ends of the piston-vanes are partially filled with oil to lubricate the slide and , via holes in the vane, the 'big ends', which would probably help sealing to some extent , as they would be pressurized . Other chambers in the casing hold oil for the main bearings. Strangest of all though , is the rotary valve on the right of Fig 1 which is driven at three times crank speed. It controls the input of the steam into the long tubular chamber i3 and its exit into the reversing/distribution chamber L at the bottom . The ports for the valve are at 90 degrees to each other meaning that steam is 'stored', briefly, in the tubular chamber whose volume is controlled by a piston i4 . The piston can be moved with a control rod i6 which is locked by holes i7 along its length. The piston can be closed allowing a spigot to close off the steam supply completely." "The steam enters through the D shaped port in one end of the crank which forces the piston-vanes to rotate the crank , filling each chamber in sequence. The steam exits through an identical port in the opposite side of the other end of the crank. A reversing valve at the bottom of the engine selects which end of the crank to supply with steam." Image from US patent 720,818 for 17 Feb 1903

Left: This is not the Margaret Knight you are looking for If you Google 'Margaret Knight rotary engine' this is the picture that is usually coupled to the name. However Knight died in 1914 at the age 76 of and this woman has clothes and a hair style that only became popular some 30 years later than that. I'm not quite sure what's going on, but I suspect dirty work at the crossroads. Perhaps someone thought that a pretty but fake picture would inspire young ladies to emulate her in STEM. If you are considering it, bear in mind that Margaret's estate at her death was valued at less than $300. This version of the picture has been annotated. Not by me; other people have noticed the avalanche of fakery. Bill Todd searched YouTube, and found that the videos before about 5 years ago do not use an alleged photograph of Margaret but only drawings (poor ones!). After that, they all use the young woman's image. Be warned! Note the two 'ofs'. What can it all mean? When Googling, be aware there are a lot of Margaret Knights out there; look for Margaret Eloise Knight. The photograph that was displayed here recently proved to be the wrong Margaret Knight; my apologies.

Left: The Margaret Knight rotary steam engine from patent 720,818 animated: 1903 This fine animation is by Bill Todd

THE PEARSE-IEVERS ENGINE: 1903

Left: The Pearse-Ievers compound rotary steam engine: 1903 This engine has four chambers with rotating lobes, of increasing sizes, ambitiously aiming for quadruple expansion of the steam and thus (in theory) higher efficency. Quadruple expansion was sometimes used in large reciprocating marine engines, where the highest possible efficiency was required, but it was not normally used ashore. The low-pressure cylinder had to be very large. This engine is unknown to Google and so was presumably not successful. Note that 'Ievers' is not a misprint for 'Levers'. The two patentees lived in Buenos Aires, Argentina.

Left: The Pearse-Ievers compound rotary steam engine: 1903 Figure 13 is a section from the side, while Figure 14 is a view from above with the top half of the casing removed. The blue areas are the four cylinders containing the rotating lobes.

Harry PEARSE was born in Plymouth, Devonshire, in 1862, worked on the Great Western Railway at the Swindon Works and then at the Hammond Electric Light Company in London. In 1888 he was appointed Chief Draughtsman at Campana Locomotive Workshops of the Buenos Ayres & Rosario Railway, promoted to Acting Locomotive Carriage & Wagon Superintendent in 1890 and confirmed in 1891. In 1902 he became Chief Mechanical Engineer of the combined Central and Rosario Railways, a position from which he retired in February, 1911. Harry Pearse died at Addo, Cape Province, in 1931.

Eyre Francis IEVERS was on 10 April 1873 in Tonbridge, Kent, son of Eyre Ievers (1846-1926) and Jane Perrier Osbourne. He was educated at Tonbridge Castle (preparatory, 1880-1884) and the Tonbridge Grammar School (1884-1887). His apprenticeship was at the locomotive works of Neilson & Co. in Glasgow (1887-1890) following which he studied at the Crystal Palace Engineering School (1890-1891) and Kings College, London (1892-1893) while working as an improver at a Great Eastern Railway running shed. In 1893 he went to Argentina, employed by the Buenos Ayres & Rosario Railway as a draughtsman in their workshops at Campana (1893-1895.) For the next two years to 1897 he was a District Locomotive Superintendent, then Works Manager (1897-1898), Assistant Locomotive Superintendent (1898-1901) and Acting Locomotive Superintendent (1901-1902). In 1901 he returned to England where he was manager of the Eyre Smelting Co., London, from 1902 to 1904, and export manager for the Galena Signal Oil Co. from 1904 to 1908. In 1908 he was back in Buenos Aires as partner in Percy Grant & Co., engineers and representatives of manufacturers of machinery, rolling stock and other railway equipment. Eyre F Ievers died 8 December 1958. Ievers was elected MIMechE on 21 July 1909.

From: Who was Who in Argentine Railways, 1860-1960.

THE PALINDROME ENGINE: 1906

Left: The Palindrome compound rotary steam engine. The operation of the Palindrome engine is rather enigmatic, as no diagram of the internals was published in my source, but there was a lengthy description in the text. There was a rotary piston and a rotary valve, coupled with spur gearing to rotate in opposite directions at the same speed. The piston had a flat vane, and the valve a hollow cylinder, rotating on a fixed tube through which the steam entered. There does not appear to be a major breakthrough in technology here.

It is not quite clear what the picture represents- it looks more like two identical engines coupled together rather than a compound engine, which would presumably have one rotor casing obviously bigger than the other. The larger bottom part of the casing no doubt contains the rotor, and the smaller section above it the rotary valve. There is another even smaller housing above that, which may or may not be interconnected with the reversing lever- possibly it contained a stop valve.

Why 'Palindrome'? Well, a palindrome is a word or phrase that reads the same in either direction. This is presumably a reference to the fact that the engine was reversible, though this was by no means the first reversible rotary steam engine.

From the article: "Great things are expected from the engine by the inventors, and a syndicate is, we understand, being formed for the purpose of exploiting the invention."

THE ELLIS ENGINE: 1906

Left: The Ellis rotary steam engine. The Ellis engine is of the common eccentric-rotor moving-vane type. Its only real point of interest is that it originated from New Zealand. This info is extracted from the patent specification, No 21409. Apologies for truly dire image quality. Source unknown #6

THE CHRISTIE ENGINE: 1906

Above: The Christie rotary steam engine. Source: US Patent 814,018 dated 1906

THE CUMMINGS ENGINE: 1907

Left: The Cummings rotary steam engine: 1907 The intended operation of the Cummings engine is hard to fathom, even after reading the patent. There are steam inlet ports J and exhaust ports L. Louis E Cummings (of St Joseph, Missouri) was granted US patent No 861,164 in July 1907. Apart from the patent no trace exists of him on Google so it would appear the idea did not prosper. This info is extracted from US patent No 861,164. (1907)

THE BLEECKER ENGINE: 1907

Left: The Bleecker rotary steam engine: 1907 A US patent for this engine was granted to Warren Floyd Bleecker of Victor, Colorado, in September 1907. One-third shares were assigned to his brothers Frederick and Martin. "In the upper part of the casing there is a rotary abutment..." which is labelled 23 in the drawing, and has a cutout to permit the radial wing 13 to pass. This abutment is coupled to the main output shaft by a pair of spur gears. 28 is an oil-cup lubricator. 37 is the exhaust port. The Bleecker engine is unknown to Google apart from the patent and this website, so it did not thrive. From US patent 865,964

THE KEATS ENGINE: 1909

Left: The Keats rotary steam engine Robert Keats of Portsmouth, England puts forward another version of Pappenheim's cogs. The restricted passages for steam entry and exit look rather dubious, but that would be the least of the problems, which include no expansive use of steam and the usual sealing difficulties. This info is extracted from UK patent specification, No 25,388. (1909)

THE LEE-BROWN ENGINE: 1910

Left: The Lee-Brown rotary steam engine This engine was designed and built by Herbert Lee and John Bryden Brown of New South Wales, Australia, in 1910. Two slipper pads push against the eccentric rotor, presumably kept in contact with it by external compression springs pushing on the two plungers. The slipper pads rock on the ends of the plungers, rather than swivelling, to maintain close contact with the rotor, but how that rocking motion could be sealed is not clear.

The Lee-Brown engine is here described in an extract from the Minutes of proceedings of the Engineering Association of New South Wales, for 9th June 1910. Most of the paper was devoted to the subject of steam turbines, but this section at the end dealt with rotary-piston steam engines:

THE WHEELER ENGINE: 1911

The Wheeler engine is one of the select number of rotary engines that were actually built, went into some sort of production, and were apparently sold.

Left: The Wheeler Compound rotary engine: 1911 This engine was given a brief article in the US magazine MotorBoating, shown here. It looks as if steam enters at the top through the stop-valve, and the exhaust is on the side of the casing. The two large screw lubricators hint at some difficulties with friction, despite the statement that the engine requires no internal oiling. The engine is reversible, which is essential for marine use, and according to the text could also be run simple (ie with HP steam admitted to the LP part of the engine) for greater power with less economy; probably this was controlled by the smaller handwheel. The throttle and reversing lever is at the extreme left of the engine. The impractically short propellor shaft was presumably for demonstration purposes only. The chain at right drives the rotary steam admission valve (see below) from the output shaft, both running in the same direction. However, in Wheeler's patents the drive is by spur gears which would rotate the valve in the opposite direction. William W Wheeler (of Meriden, Connecticut) was granted US patent 788,179 in 1905, US patent 935,079 in 1909 and US patent 982,329 in 1911. The first was for a vane-type rotary rngine, but the last two covered gear-type engines as shown here. From MotorBoating Dec 1911 p88

Left: The internals of the Wheeler engine: 1911 The explanation of its operation in US patent 935,079 is lengthy and far from clear, but basically it is another gear-wheel engine, with two expansion chambers marked 10. The HP chamber is on the right and the LP on the left, with steam passing from one to the other through passage 22. In reverse the roles of the chambers are interchanged. Reversing was accomplished by turning the rotary valves marked 26, so that the exhaust came out of the right pipe marked 25 rather than the left. Part 40 is a rotary steam admission valve that rotates at the same speed as the output shaft; exactly what this does and how it interacts with the cog-wheels is unclear from the patent. Part 38 is the valve which admits steam to the LP cylinder when high torque is required. According to this patent a pretty hefty flywheel was required on the output shaft, but there is no sign of it on the photograph above. From US Patent 935,079, Sept 1909

Left: Side view of the Wheeler engine: 1911 This shows the gears 43,44 that drove the rotary admission valve in the top of the casing. 25 is an exhaust steam pipe, and 35 the main steam supply pipe. One of the advantages of the rotary steam engine is supposed to be its smooth torque, and one cannot help wondering why the heavy flywheel 56 was required. Wheeler and the Rotary Engine & Power Company are, apart from this one entry, unknown to Google, which would indicate the company did not prosper even slightly. From US Patent 935,079, Sept 1909

THE MCEWAN ROSS "ROTA" ENGINE: 1912

Left: The McEwan Ross "Rota" rotary steam engine Some further details on this machine have recently been uncovered. Firstly, I have for some time described this as the "McEwan & Ross" engine, but it appears that Mr McEwan Ross was just one person. Secondly, the internal arrangements are now known in detail. See below: From The Book of Modern Engines by Rankin Kennedy. Volume 2, p19. Pub Caxton Publishing Company, London, in 1912.

Left: Section of the McEwan Ross "Rota" engine. The eccentric shaft e-e rotates around the central shaft b-b, carrying around the four cross-arms. The four pistons move up and down these arms, inside the eccentric cylinder d. This causes the spaces between the pistons to expand and contract, and filling and emptying these volumes with steam generates rotation. Cylinder d rotates with the pistons, minimising their relative velocity. Now this looks a bit more like it. There appear to be no line contacts which make sealing virtually impossible, but instead broad areas at the outside ends of the piston which could be effectively sealed with something like piston rings. Also, the rotating cylinder should reduce friction and wear. From The Book of Modern Engines by Rankin Kennedy. Volume 2, p19. Pub Caxton Publishing Company, London, in 1912.

Left: Side section of the McEwan Ross engine. Steam enters via the hollow support column on the left, and leaves via the column on the right. From The Book of Modern Engines by Rankin Kennedy. Volume 2, p19. Pub Caxton Publishing Company, London, in 1912.

Left: Animation of the McEwan Ross engine. This shows how the volumes between the pistons expand and contract due to the eccentric mounting of the shaft carrying the cross-arms. This most excellent animation is kindly provided by Bill Todd.

THE BROWN ENGINE: 1912

THE MARKS ENGINE: 1912

Left: The Marks rotary steam engine; cross-section. A is the main rotor, with two vanes, and B and C are auxiliary rotors that rotate at the same speed, synchronised by external gearing, and having cutouts into which the vanes of A fitted. On the outside of B and C are two narrow channels in which steam presses these rotors inward to avoid sliding friction, and indeed the inventor claimed that there was no metal-to-metal contact inside the whole engine. If this was true it was a remarkable achievement. A small experimental engine delivered 10 HP with 80 psi steam, running at "well over 4000 rpm, and maintaining this speed without noticeable heating." a reference to the high frictional losses in the average rotary steam engine if it was packed to be steam-tight. D, E,F, and G are rotary exhaust valves. Steam admission was by ports in the casing end-plates, passing through the wedge-shaped passages in rotor A. This design appeared in The Automobile Engineer, date unknown. No US patent for it has been found. From The Book of Modern Engines by Rankin Kennedy. Volume 6, p12. Pub Caxton Publishing Company, London, in 1912.

THE SPIRO ENGINE: 1912

Left: The Spiro rotary steam engine: 1912 This engine was promoted by its makers as 'The Spiro Turbine'. In fact it does not appear to have been any sort of turbine, but rather a rotary engine that worked as the inverse of the gear-wheel pump. It is very possible that the makers were trying hard to avoid the title 'rotary engine' because at this point the concept was pretty much totally discredited.