A tidal mill at East Greenwich
In his Treatise of Mechanics ... 1, Olinthus Gregory described a 'species of tide-mill ... which has lately been erected on the right bank of the Thames at East-Greenwich'. His description was repeated, virtually verbatim, by Luke Herbert in 1849. 2 It was also summarised (without attribution) in an article in The Engineer in 1901; 3 and was mentioned briefly by Rex Wailes in his 1938 work on tide mills. 4 The mill had a number of interesting features: in particular that the water wheel rose and fell with the tide; that it also operated in both directions with the tide and that the mill gearing required adaptation to cope with the rise and fall.
Olinthus Gregory (1774-1841) was a mathematician with multiple interests, including music and astronomy. Among other topics, he wrote a treatise on the slide rule; conducted experiments with a pendulum and on the velocity of sound; and was involved in setting up a secular university in London. 5 The Treatise was in two parts; Part One was about the theory of mechanics; Part Two covered Practical Mechanics and Description of Machines in alphabetical order — for example, the section on Tide Mills is followed by one on 'Turning', with illustrations of Maudslay's machinery.
Olinthus Gilbert Gregory 1774-1841
However, Gregory does not seem to have been very well informed about tide mills in Britain. In an introductory section before turning to the East Greenwich tide mill, he said:
Mills of this kind have not often, we believe, been erected in England, though several of our rivers, and particularly the Thames, the Humber and the Severn, in which the tide rises to a great height, furnish a very powerful mover to drive any kind of machinery, and would allow of tide-mills being very advantageously constructed on their banks. The erection of such mills is not to be recommended universally, as they are attended with a considerable original expence [sic]; besides that some of their parts will require frequent repairs; but in some places where coals are very dear they may, on the whole, be found less expensive than steam-engines to perform the same work, and may on that account be preferred even to them. 6
He said he was 'unable to ascertain who was the first contriver of a tide-mill in this country, nor at what time one was first erected' and looked to France for information. He was clearly unaware of the extensive history of tide mills in England, at least from medieval (and possibly Roman) times onwards, including not only those on London Bridge but numerous mills on the Thames and the Lea, as well as in Essex, Suffolk, Hampshire and Pembrokeshire. The author of the piece in The Engineer seems to have been similarly ill-informed — he referred to the East Greenwich tide mill as 'the largest and most complete tide mill we have any account of' and was clearly unaware of the Three Mills and Four Mills complexes on the river Lea, just across the Thames from Greenwich. Gregory's interest in the East Greenwich mill seems to have been sparked by walking along the riverside from Woolwich, where he was Professor of Mathematics at the Royal Military Academy, 7 and he recorded what he found at the site. 8
Gregory said the mill was erected 'under the direction of Mr John Lloyd, an ingenious engineer of Brewer's Green, Westminster'. 9 A Greenwich Industrial History Society article refers to Lloyd as a leading millwright, with a business based in Brewer's Green (which is adjacent to Buckingham Gate in Westminster), 'but within two years had moved to Nelson Square in Southwark as a partner in Lloyd and Ostell'. The same article says 'Lloyd and Ostell were government contractors and were to install the equipment at Waltham Abbey Gunpowder Works and a number of other important sites.' I have been unable to discover any further information about John Lloyd or Mr Ostell.
Although Gregory did not mention him, the article in The Engineer refers to a patent, No 2411 granted on 10 June 1800 to William Johnson of Bromley, for the method of raising and lowering the water wheel with the tide. Johnson also appears to have been involved in the construction of the mill (see below).
Location and structure
The article in The Engineer says the mill
was erected on the bank of the Thames, about midway between the spot now occupied by the Blackwall Tunnel and Woolwich. ... a large part of the pond attached to these mills is still traceable, though a good deal has been filled up with cinders, and the works of the Blackheath and Greenwich District Lighting Company occupy nearly the site of the old tide mill.
The mill was built on the east side of the Greenwich Peninsula, on Bugsby's Reach. Although the Mill was built in 1804, the Ordnance Survey map 1805-22 still identifies the site as 'Over Brickfield'. Mary Mills suggests that this was the site from which 'Russell's workers had dug ... brick earth' and that the brick earth pits may have been used to construct the millponds. 10 The Mill shows clearly in a map of 1834 (Figure 1). 11
Figure 1. Plan of Parish of St Alphage Greenwich. Greenwich Heritage Centre
Gregory recorded that the 'mill-house' — which I take to mean the mill building, not the miller's residence — was 40 feet wide and 'parallel to the course of the river' and that there was a forty-foot waterway from the river to the mill, to fill a 4 acre reservoir; beyond this was a smaller reservoir 'let out occasionally at low water to cleanse the whole works from mud and sediment, which would otherwise in time clog the machinery'. Four reservoirs or ponds are shown in a Survey of Greenwich published in 1834 (Figure 2).
Figure 2. Survey of Greenwich 1834. Greenwich Heritage Centre
The building at the far right of a print by Samuel Hill, 'Shooter's Hill from Woolwich Reach', is generally thought to be the East Greenwich Tidal Mill (Figure 3).
Figure 3. Samuel Owen, Shooter's Hill from Greenwich Reach. Reproduced with permission of the National Maritime Museum
An article in the Greenwich Industrial History Society magazine says it was William Johnson who applied to the Commission of Sewers for 'permission to open the sea wall', 12 and to the Thames Conservators a year later; and that he commissioned a civil engineer, Mr Hollingsworth, to 'open the sea wall'. The structure was therefore quite different from mills which dam a river, where the water wheel is parallel to the river flow. This mill had a reservoir directly off the river Thames and the water wheel was at right angles to the river.
The mill was constructed to grind corn. The Engineer article says it was for the London Company for the Manufacture of Flour. In the light of Gregory's comment on costs, it is interesting that it was found economic to construct a tide mill, even though a Trevithick steam engine was purchased to assist with construction of the mill. The steam engine was the subject of an explosion in 1803. 13
The water wheel was 26 feet in 'length' (sic), with a diameter of 11 feet and with 32 float boards. In an advertisement in 1800 (before the mill was finished), Johnson estimated that:
when the tide rose 15ft. a basin 125 yards square and 21ft. deep would hold enough water to grind and dress 468 bushels of wheat every twenty-four hours, or every twenty working hours, four being allowed for stopping to let the tide get a good start. 14
There was a tidal range of 20 feet. Gregory said the water 'is suffered to enter and fall upon the wheel at the sluice Q', at the bottom of the frame, showing it was an undershot wheel. 15 The water wheel operated 8 pairs of millstones.
The rise and fall mechanism
The water wheel was carried in a wooden frame, which rose and fell with the tide. The wheel was constructed in four parts:
the parts of the float-boards belonging to each of these portions fall gradually one lower than another, each by one fourth of the difference from one board to another [see Fig 6 in Gregory's illustration (Figure 4)]. [This was] intended to equalize the action of the water upon the wheel, and prevent its moving by jerks'. 16
Figure 4. Gregory's Treatise, Part 2, Plate XXXV (detail). Reproduced with permission of the Science Museum Library/Science and Society Picture Library
He went on to describe the mechanism for allowing the wheel to rise and fall with the level of the tide. This involved a pair of folding gates, TW in Gregory's Fig 5 (Figure 4). When the water enters the wheel
the hydrostatic pressure acting against the bottom of the wheel frame S, and at the same time acting between the folding gates TW, which are thus converted into very large hydrostatic bellows, buoys up the wheel and frame (though weighing ... nearly 20 tons) and makes them gradually to rise higher and higher so that the wheel is never ... drowned in the flowing water ... In this way the wheel and frame are buoyed up by a head of 4 feet; and the mill works with a head of 5 or 5½ feet.
In the reverse direction of the tide, to avoid water being confined between the wheel frame and the folding gates, strong racks of cast iron enabled the wheel frame to be suspended or gradually let down, presumably manually.
Operation in both directions
It is a common misconception that tidal watermills normally operated in both directions, i.e. in one direction as the tide flowed upstream and in the reverse direction as the tide ebbed. This was not the case in most British tide mills, which impounded the water at the peak of the tide and released the water to turn the water wheels on the ebb.
At a conference in 1999, David H Jones discussed schemes which involved separate sets of machinery for each direction and other schemes. He went on:
Another option was the reversible waterwheel, which presents both mechanical and hydraulic problems. In particular, arranging for the water to drive the wheel efficiently in either direction is difficult, but the surviving proposals concentrated on the mechanical rather than the hydraulic problem. A group of such mills existed in Chesapeake Bay. The surviving example had a long working life and obviously gave satisfactory service. The mechanical problem was easily solved by swinging the wallower between two opposing pit wheels and driving the stones from the upright shaft with a belt. At these sites, the hydraulic problem was avoided, as the tide range was very small. Such operations must have required a very large pond, which seems to have been naturally available. Clearly, these mills were built to suit unusual local conditions which are not comparable with European tide mills. 17
Similarly, at a Conference in 1938, the Chief Engineer of the Three Mills Distillery, Mr W M M Shepherd, said 'The water could not be used both ways; as soon as the tide had turned the gate closed.' Asked whether some of the incoming tide could not be used, Mr Shepherd said 'when the tide came up to three-quarters it would be level with the down-coming water.' 18 How did the East Greenwich mill deal with these problems?
In an orthodox mill, a pit wheel is fixed on the same axle as the waterwheel and therefore turns in the same plane. The pit wheel drives a wallower which in turn drives a vertical shaft (thus changing the plane of motion) which, via a spur wheel and stone nuts, drives the upper millstones (runner stones). In Gregory's description of the operation at East Greenwich (see Figs. 5 and 6 in Gregory's illustration above, Figure 4), a cog wheel — effectively a pit wheel — was fixed to the water wheel and it therefore turned in the same plane. The cog wheel drove two wallowers, one at the top and one at the bottom of a vertical shaft. By raising or lowering the shaft, one of the wallowers was engaged to be turned by the wheel operating in the appropriate tidal direction, leaving the other wallower disengaged. The shaft was raised or lowered manually by a lever (G on the drawing), assisted by the gearing at top left of the waterwheel. Thus, as Gregory concluded, although the wheel's motion is reversed for the next direction of the tide, it will 'communicate the rotary motion to the vertical shaft always in the same direction'. There was a delay between the two operations until there was sufficient head of water to turn the wheels in the outflowing direction.
This arrangement, combined with the rise and fall of the wheel, appears to deal with the reservations by Jones and Wailes. The rise and fall mechanism coped with the problem of 'drowning' the wheel and there were two wallowers rather than the two opposing pit wheels and duplicated machinery to which Jones refers. It is clear from a late reference in the treatise that this machinery was at each end of the waterwheel, presumably operating two sets of machinery.
The grinding and ancillary machinery
Gregory explained how the gearing to the millstones and other machinery coped with a rising and falling water wheel: there was a
vertical shaft, with wallowers and a first cog-wheel, as F, E, and CD; and each of these vertical shafts turns a large horizontal wheel at a suitable distance above the wallowers, while each horizontal wheel drives 4 pinions placed at equal or quadrantal [sic] distances on its periphery, each pinion having a vertical spindle, on the upper part of which the upper millstone of its respective pair is fixed. Other wheels driven by one or other of these pinions giving motion to the bolting and dressing machines, and different subordinate parts of the mill.
Although the vertical shaft at each end of the water-wheel rises and falls with that wheel, yet the large horizontal wheel turning with such shaft does not likewise rise and fall, but remains always in the same horizontal plane, and in contact with the four pinions it drives. The contrivance for this purpose is very simple, but very efficacious: each great horizontal wheel has a nave, which runs upon friction-rollers, and has a square aperture passing through it vertically, just large enough to allow the shaft P to slide freely up and down in it, but not to turn round without communicating its rotatory motion to the wheel: thus the weight of the wheel causes it to press upon the friction rollers, and retain the same horizontal planes, and the action of the angles of the vertical shaft upon the corresponding parts of the square orifice in the nave causes it to partake of the rotatory motion, such motion being always in one direction in consequence of the contrivance by which one or other of the wallowers EF is brought into contact with the opposite points of the first cog-wheel CD.
This appears to have been different from the orthodox mill machinery, in which a great spur wheel engaged with the vertical shaft, to turn stone nuts which turned the millstones from below; and a crown wheel engaged with the top of the vertical shaft to operate smutting and dressing machinery, a sack hoist etc. Unfortunately, while Gregory illustrates the Tide Mill section of the Treatise with two plates (XXXV and XXXVII), containing 22 figures, in this part of the text he refers only to Figs 5 and 6 (see Figure 4). Clearly, the vertical shaft was longer than shown in Fig. 6, and appears to have extended upwards to engage with the 'large wheel', which undertook the function of the great spur wheel in an orthodox mill. Gregory's Fig. 1 (on the copy above) appears to show the 'large wheel', and Fig. 2 one of the 'pinions' which drove the runner stones. The figure also shows the vertical shaft projecting higher still, to operate the millstones, while one of the pinions turned one or more other wheels which operated the ancillary machinery.
According to notes kindly provided by Mary Mills, 19 Johnson lived in the Mill House until 1807, when he was replaced by William Doust. The original project included cottages to house the mill workers and a public house, the whole to be known as 'New East Greenwich'. 20 Later the Mill is sometimes recorded as belonging to Thomas Patrick; indeed, it was often known as 'Patrick's Mill'. In the late 1830s, the ownership changed again and the mill may have been used for the manufacture of chemicals. Mary Mills continues:
Records show a number of short term owners in the early 1840s but it was eventually acquired by Frank Clark Hills ... Hills was an industrial chemist, hitherto based at the Deptford Chemical Works in Copperas Street, Deptford. ... It seems likely that corn continued to be ground at East Greenwich under Hill's ownership but it is not clear if the tide mill continued to work. From 1845 it was described as a 'steam flour mill' and perhaps the tide mill itself was replaced by a 25 horse power steam engine.
The site was later occupied by the power station of the Blackheath and Greenwich Lighting Power Company, which was built in 1900.
David Plunkett, in consultation with David Jones, questions the nature of the sluice gate, 21 which Gregory mentioned several times. Gregory said the sluice gates (in the plural) were 'carried down to the low water-mark in the river'. 22 Gregory also referred to the smaller reservoir 'in which water is kept', which implies a sluice gate to impound the water, but in none of these references did he describe the form of the gate.
David Plunkett suggests a number of options: a single vertical gate or a multi-part gate; and questions whether it was it resting on a cill within the frame when closed, or associated with a hinged spring-loaded gate. 23 He suggests a third option incorporating big long stop boards linked by chains. He also raised the question of counter-balance weights, which would have been an important part of the operation and which were also not mentioned by Gregory. The gates and the counterweights are, however, both mentioned in the article in The Engineer, which says 'a system of counterweighted gates was employed to regulate the flow of water to the wheels [sic]'.
These uncertainties lead Mr Plunkett to question how far the method was successful. There are reports of difficulties with the operation, for example the hard work involved in winding the gear wheel up and down to align the waterwheel correctly, and the need to manually change wallowers with the changing direction of the tide. Perhaps the fact that the Mill appears to have operated for only about 40 years, while tide mills at Three Mills across the Thames continued to operate for another century, may suggest that, while very interesting, it was not particularly successful. This article therefore leaves unanswered questions which others may be able to pursue.
I am grateful to Mary Mills for drawing Gregory's Treatise to my attention and sending me copies of the text and illustrations and other notes. I must also thank David Plunkett and David Jones for their comments and suggestions. I am also grateful to the Science Museum Library/Science and Society Picture Library for scanning the plates and sending me clearer copies, without which this article could not have been written. My thanks also go to the staff of the Guildhall Library, the Guildhall Art Gallery, the London Metropolitan Archives, the Greenwich Heritage Centre, the Museum of London and the National Maritime Museum for their help with the illustrations.
Notes and references
1. Gregory, Olinthus Gilbert. A Treatise of Mechanics Theoretical, Practical and Descriptive. Geo. B Whitaker, 1826, pp 462-470
2. Herbert, Luke. The Engineer's and Mechanic's Encyclopaedia, Vol. 2. Thomas Kelly 1849
3. The Engineer 12, VIII 1901
4. Wailes, Rex. Tide Mills in England and Wales, Part One, The Society for the Protection of Ancient Buildings, 1938, pp 7-8 – lecture read at the Institution of Civil Engineers, London, October 12th 1938
5. O'Connor, J J and Robertson E F, article in MacTutor of Mathematics, St Andrew's University November 2010. There is also a potted biography in Wikipedia, which does not mention the Treatise
6. Gregory op cit, p 462
7. O'Connor and Robertson, op cit
8. '200th Anniversary of an Industrial Accident on the Greenwich Peninsula', Greenwich Industrial History Society, 6, Issue 5, September 2003
9. Gregory, p 463
10. Mills, Mary. Greenwich Marsh 1999, p 37
11. Plan of Parish of St Alphage, Greenwich from an actual survey by W R Morris 1834
12. 'Who was the Pilot at The Pilot??' Greenwich Industrial History Society May 2013
13. '200th Anniversary ...' op cit
14. The Engineer, op cit
15. Gregory, p 405
16. David Jones comments that the staggered buckets were not unique: they existed at a cotton mill in Belper in the late 18th century. Private communication February 2014
17. Jones, David H. 'How Tide Mills Work' in Open to Tide Mills, Proceedings of an International Conference ... held on 11 September 1999, River Lea Tidal Mill Trust 2000, p 9
18. Wailes 1938, op cit
19. Mills, Mary. 'William Thomson and East Greenwich Tide Mill', private communications
20. Mills, Mary. 'The Georgian Cottages on the New Millennium Experience Site', Greenwich Industrial History Society, Issue 1, April 1998
21. Private communication, 27 December 2013
22. Gregory, pp 463-4
23. David Jones questions whether a spring-loaded folding gate was necessary, as tidal water pressures may have been sufficient, but corrosion and friction over time may have necessitated some new or extra counterweights
© GLIAS, 2015