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Brisbane's Tower Mill

We all treasure the old windmill on Wickham Terrace but let’s be honest – it looks a bit dull. The building as it stands today, in its 1860’s incarnation as a signal tower, is well maintained but it is very hard to envisage what the original sandstone and brick façade looks like under the concrete rendering, and to imagine the mill in its original state with an encircling gallery, a handsome cap and sails turning in the wind. It is even harder to picture the ancillary, convict-powered treadmill of which nothing remains. The two must have been quite a sight, sitting there as beacons of hardship and emerging industry on the ridge above the young settlement.


In this piece we will recreate the windmill and treadmill as they appeared in the late 1820s and 1830s, as faithfully as possible based on all available records. We will forego the subsequent history of the mill which is well documented elsewhere. For a succinct summary I recommend the entry in the BCC/Queensland heritage register, located here.


Let’s look at the renderings first, and then consider the historical research and design details. All of the below images can be enlarged by clicking.

Visual Tour

The two sibling buildings were completed in 1828, only a few short years after the relocation of the small convict settlement to Brisbane and during the productive but harsh reign of Captain Patrick Logan. The treadmill was included in the development from day one, to provide reliable grinding power in the rather windless climate and a means for physical punishment of disorderly convicts. 


The title image shows the eastern aspect of the buildings. The windmill belonged to the robust "tower mill" category and it had a rotating cap and a "fantail" which automatically turned the sails into the wind. An encircling timber platform or "gallery" provided access to the high-set sails for maintenance and adjustments. The original facade, which is still present under the concrete rendering, consists of blocks of sandstone,  tuff and convict-made sandstock bricks. A high timber palisade encircled the site for protection and containment, and the top of the ridge was cleared of large trees to improve airflow.


In the below picture we see the mill from the old convict path that ran along today's Wickham Terrace.

The treadmill was sheltered by a shed measuring roughly 9 by 12 meters, which was offset by 90 degrees from the windmill and stretched diagonally across the path of the future Wickham Terrace. The far edge of the shed reached what is now the pavement on the other side of the road.

A closer view of the "business side" of the treadmill.

The treadmill was designed according to a British standard developed in 1818 which became widespread throughout the Empire. It comprised two separate wheels, each of 5.8 meters length, mounted on a single timber shaft. The combined wheel was about 12 meters long with a diameter of 1.6 meters and twenty-four steps around the circumference. The shaft extended into the windmill where it connected vertically to a pair of millstones on the first floor or "stone floor".

Sixteen convicts would be "stepping" on the wheel at any time with eight persons resting, creating a relay of one-third. Convicts would climb onto the wheel at one end and shuffle one position every ten revolutions or roughly every five minutes before stepping off at the other end. During normal use, each person would be treading for a total of about 5 hrs and 20 minutes in a working day, taking about 15,000 steps equivalent to a 3,300-meter climb. During "punishment" use the working day was prolonged and the relief crew was reduced, increasing the stepping time to 11 hours and the ascent to 5,500 meters. Many convicts wore leg irons whilst on the treadmill.

In the next image we see eight convicts, or one-third of the chain gang, resting in the shaded space behind the wheel. The west-facing side of the shed provided some shelter from the sun in the morning and mid-day.

The rear of the treadmill, exposed to the late afternoon sun.

The compound viewed from a location further down Spring Hill.

Top view of the mill and the surrounding circular palisade, corresponding to the 1839 detail map shown in a later section.

The two buildings overlaid on a modern aerial photo of Wickham Terrace, viewed from the North.

Details of the Windmill

There are no surviving plans or specifications for the windmill so any recreation must be based on eyewitness accounts, contemporary sketches and findings from later restoration projects. 


Illustrations of the mill created over the years appear to be based on a series of sketches produced by the Assistant Commissary-General Henry Boucher Bowerman in the period 1831 to 1835, depicting the penal settlement as seen from South Bank and Kangaroo Point. The sketches were by all accounts produced in-situ and the details of buildings such as the commissariat store and convict barracks are quite accurate, so we can assume that the distant windmill is also reasonably correctly reproduced. The sketches confirm several design features.

Details from sketches of the Moreton Bay settlement as seen from South Brisbane (top) and Kangaroo Point (below) ca. 1831-1835, attributed to Henry Boucher Bowerman. 

Firstly, the mill was a "tower mill" which set it apart from the older category of “post” mills. Tower mills and their sisters the “smock” mills have rotating caps which turn the sails into the wind. Post mills, in contrast, have to be pivoted around the vertical axis in their entirety, including all internal components and stores, and as a consequence are lower, more light-weight and typically made of timber. The emergence of tower mills enabled millers to build high into the undisrupted air flow and also the strength to withstand storms – useful features in a region such as ours where the wind is generally absent until it blows your roof off. 


We can see that the mill had an encircling platform or “gallery” which allowed access to the high-set sails for maintenance and adjustments, and also a rounded or possibly slightly tapered cap finished with a spire. The cap had a “fantail”, or a smaller rotor which automatically turned the sails into the direction of the wind. There is no more information of use to us other than the apparent presence of a high fence or palisade between the buildings and the slope of the hill, which from the sketches appears to be circular.


Another key reference is a map of the penal settlement drawn 1839. Again the map includes dimensions of other buildings with high accuracy and we can assume that the same applies to the windmill and the attached treadmill. The diameter of the mill is about 13 meters which accurately reflects the tower with a standard gallery. The dimensions and orientation of the treadmill shed can also be confirmed and will be discussed later. By overlaying the map on a modern aerial photo we can see that the path from the settlement traversed the hillside diagonally, turning in a hairpin at the top of today’s Jacob’s Ladder and followed the approximate path of Wickham Terrace to the mill. 

1839 map of the moreton Bay settlement including the windmill and treadmill (left), and detail overlaid on a contemporary aerial photo (right). 

The map also shows the circular fence present in Bowerman’s sketches - a substantial construction with a diameter of about 53 meters. The drawings give the impression of a continuous wall of sharpened slabs or palings consistent with a palisade. My model has quarter-split logs of about 3 meters’ height around the full circumference. Historical records suggest a dual motive for this feature - to contain the escape-prone convicts and defend the produce. Tom Petrie’s memoirs mention multiple robberies of the miller by local tribesmen.


An elevation of the tower in its current observatory incarnation was produced by Brisbane City Council in 1949.  The section shows the four levels of the mill which correspond to the standard partitioning of tower mills, namely from top to bottom; a “dust floor” containing the mechanism which connected the sails and wind shaft to the vertical shafts; a “bin floor” containing the grain hoppers, a “stone floor” which held the two pairs of millstones and finally the “ground floor” where the milled product was collected and sacked. Each level has windows; one casement opposite the front door on the ground floor, two each on the stone and bin floors and a series of 8 smaller openings encircling the dust floor. The precise dimensions of the tower were derived from these two drawings.

Elevation and section of the tower mill signal station. Brisbane City Council, 1949.

There have been two major initiatives to restore or preserve the mill in the past 40 years, each of which have left behind useful documentation. The first attempt was in the late 1970s when serious consideration was given to a full restoration to the original mill including sails, gallery and internal working mechanisms. A study was commissioned by the Queensland National Trust resulting in a research report by Janet Hogan (1978). Original plans could not be located and engineering reports on the sandstone and brick fabric advised against introducing of heavy loads and re-exposing the delicate façade to the elements. In the end it was recommended that the tower should be retained in its current form and fabric. The report contains details on the materials found beneath the concrete rendering - the external walls of the first floor being made of large stone blocks the majority of which are sandstone (we can assume from the Oxley Creek quarry) with some tuff (from the Kangaroo Point quarry), and the external walls of the bin and stone floors of sandstock brick. 


The architectural firm Cameron, McNamara & Partners produced sketch plans for a potential restoration which are reproduced below. The inspiration for the design is unknown but it seems likely that the Bowerman sketches played a part. 

Architect's sketch proposal for a restored windmill.

National Trust of Queensland, 1978. 

The original facade can also be seen in early photographs, taken before the brick sections were rendered in the 1880s. We can confirm that the sandstone and tuff blocks reach about one-third up the Stone Floor. The ashlar masonry appears to transition seamlessly into the brick section. Along the upmost row of blocks are marks that appear to be from joists or other structural timbers, confirming the level of the gallery. The stone re-appears on the dust floor where large blocks are arranged in an octagonal pattern of recesses and and small window openings. The photos also show plaster or timber ornamentation above and surrounding the entrance door.

Early photographs of the windmill as a signalling tower, ca 1880s

A second conservation project was undertaken in 1987 in conjunction with the construction of the nearby Central Plaza building. The story of this initiative is described by heritage architect Peter Marquis-Kyle here. During the work a section of rendering was removed, exposing details of the façade. Photographs taken confirm some of the of the known details and also show a crude but appealing lintel with a keystone above the eastern stone floor window. In the model I have assumed that the same feature was used for all windows. The study again concluded that the structure was too fragile to be exposed and that it should be preserved in its current state leaving the full historical fabric intact. The cement rendering was re-applied and has remained since.

Section of the windmill facade exposed during 1987 restoration works.

Photos courtesy of Brisbane City Council.

The records discussed above account for the bulk of the model, with some details left to deduction and adoption from contemporary windmills:


  • For the gallery, the proportions and shape of the tower were conducive to an octagonal footprint with a simple and robust timber railing taken from contemporary examples. The raking struts rest nicely on the lower circle of foundation blocks and there is no indication that they were incorporated in the external wall.


  • None of the sources show any signs of a door from the inside of the stone floor to the gallery, and my assumption is that the gallery was reached through a simple external ladder which was not uncommon for this type of comparatively low-height mills.


  • The height of the gallery constrains the size of the sails. The design of windmill sails is otherwise a whole body of knowledge in its own right with a complex taxonomy of types and sub-types. In the absence of any records I settled for a “common” design, although it is possible that a more advanced solution such as “patent sails” was used which self-adjusts the surface area depending on the wind speed. Trivia – the Patent Sail was invented by the British engineer and millwright William Cubitt in 1807, who was also the father of the treadmill design used in Brisbane as we shall see later. 


  • The details of the prominent fantail are not apparent in Bowerman’s somewhat naïve sketches and again the variety of designs is endless. The pattern used in the model is taken from the roughly contemporary (and beautifully restored) Callington Tower Mill in Hobart.


  • I have yet to see a good example of the colour and texture of convict-made local bricks, which we can assume were produced in the brickyard at foot of the hill in the vicinity of today’s Roma Street station or possibly in "Frog's Hollow" further down Albert Street. A generic brick texture has been applied to the model.


  • The shape of the cap is round with a spire – my best interpretation of the Bowerman sketches. My assumptions stretch to a whitewashed cap and brass spire.


It has been suggested that the convict miller John Oseland played a central role in the construction of the Brisbane windmill, and that he had previously been involved in the construction of  mills in Hobart, Newcastle and Sydney. I have searched for any remaining examples of his work to guide the detailing of the Brisbane mill, to no avail. Oseland escaped from the settlement shortly after the mill was finished and was never heard of again.

The Treadmill

The treadmill is harder to recreate as nothing of it remains today. Records are limited to a few maps and a handful of eyewitness descriptions, some written after the demolition of the structure in the late 1840s, and contemporary examples from other Australian settlements and the UK. Nevertheless – enough information is available to form a clear view of its design, materials and function. Starting with the eyewitness reports we have several sources to draw from. Note that the term "treadmill" has many substitutes including "treadwheel", "stepping wheel" and "treads" which are used interchangeably depending on the source.


First out, the Quaker missionary James Backhouse who visited Moreton Bay in 1836 with his travelling companion George Washington Walker:


"The tread-mill, is generally worked by twenty-five prisoners at a time; but when it is used as a special punishment, sixteen are kept upon it, for fourteen hours, with only the interval of release, afforded, by four being off at a time, in succession. They feel this extremely irksome, at. first; but notwithstanding the warmth of the climate, they become so far accustomed to the labour, by long practice, as to leave the tread-mill, with comparatively little disgust, after working upon it, for a considerable number of days."


Walker made additional notes regarding working shifts and the total ascent per person over a working day:


"29th (March). Went into the yard where the chain gang, consisting of twenty-five men, were at work on the tread-wheel. These are so employed because the power is wanted, not because it is a part of their sentence; therefore they are not so hard worked as if they had subjected themselves to this species of discipline as an extra punishment. In that case they work from sunrise to sunset, with a rest of three hours in the middle of the day, in the hot weather, and two hours during the cooler months. There is also a relief of four men, sixteen being constantly on the wheel, which, of course, affords each man an interval of periodical rest, throughout the day, of one-fifth of the whole time, or of one quarter of an hour's rest after every hour of labour. The exertion requisite to keep this up is excessive. I am told the steps of the wheel are sometimes literally wet with the perspiration that drops from the partially naked men; for they generally strip to the waist. It necessarily bears hardest upon those who have been least accustomed to the labour, particularly the men who are the heaviest in person. The Constable who was superintending, told me that the wheel performed 160 revolutions before each man's turn of rest came, which multiplied by 24, the number of steps in the wheel, gives 3840 times each man must lift his feet in continued succession. Any one who has tried the effect of ascending a hundred steps at a time, may form some idea of the excessive exertion this kind of abour involves, though, doubtless, something must be abated on account of the weight with which the men rest with their arms or hands on the cross rail."


An emotive account is provided by R. S. William in the controversial “The Fell Tyrant”, 1836:


"There is also a mill, which grinds corn and wheat for the use of the settlement, to which is affixed, a treadmill: this is at work, when there is little or no wind, so that the mill is never idle. The brutality used on this piece of machinery, is beyond the power of a human being to describe. The unfortunate men are continually falling from it apparently in a lifeless state. I recollect 2 men falling from it, through absolute fatigue and were killed.”


A more detailed account, including approximate dimensions of the treadmill, are provided by Constance Petrie in Tom Petrie’s Reminiscences:


“In order to gain a good supply of meal to make up for the other things, Grandfather Petrie got the better class of prisoners to volunteer to work the treadmill, as it was calm weather (no wind to speak of), and the mill was slow in its work. The prisoners did not object, as it meant plenty to eat for themselves as well as for the rest of the settlement. The boy " Tom " marched alongside with the convicts up to the mill, and when there he saw them go in turns to the wheel, so many on at a time. It was a very hot day, and the first lot took off their shirts, and then went up some five steps to get on to the wheel, which was like a water-wheel, and was thirty or forty feet long, and the treads being about nine inches wide. An iron bolt at one end held it steady till the prisoners were on, then when that was withdrawn the weight of the men started it moving, and they simply had to step up or be hit on the shins; they had a rail to hold on by, of course. A shaft ran through from the wheel into the windmill, where it connected with the cogwheels there—the works were something like those of a chaffcutter. To look at the convict stepping one would think they were going upstairs. They had to tread so many minutes, and when one man got off at the far end, another one took his place at the starting point. The man just off would have a rest till his turn came round again. Some took to it so well that they could just hold on with the left hand as they stepped, and with the right scribble on the boards drawings of ships, animals, and men—others seemed to tire altogether. However, on this occasion it was not a punishment, and most of them were very jolly over it, chaffing one another, and calling, " Hullo, Bill, or Jack, what have you done to be put on the treadmill? " And so they went on till plenty of meal was ground to keep things going, and a couple of days later the expected vessel turned up. She had been windbound in some bay on the coast. Father also saw the unfortunate chained men on the treadmill working out their punishment. You would hear the " click, click " of their irons as they kept step with the wheel, and those with the heavier irons seemed to have " a great job " to keep up. Some poor wretches only just managed to pull through till they got off at the far end, then they sat down till their turn came to go on again. They all had to do so many hours, according to their sentence; an overseer kept the time, and a couple of soldiers guarded them. When they had put in their time they were marched back to barracks.”


A passage by the anonymous “An Eight Year’s Resident” in “The Queen of the Colonies”, 1876:


“This building was erected in the convict period, as a windmill for grinding the maize meal which made the hominy of the convicts, or, as they are usually called in the colonies, lags. It was, however, often used as a tread-mill, and the convicts had here literally to earn their bread by the sweat of their brows. When the settlement became free the tread-mill of course fell into disuse. Although now in one of the most fashionable parts of the town, the windmill was then quite in the bush. No use was made of its machinery, and if we may credit an old man who had often stepped out his four hours there, it was gradually and quietly removed by a neighbouring blacksmith when iron was dear, and worked up into horseshoes and other articles of his trade”


A snippet from ‘Boy Travellers in Australasia”, Knox 1889:


On their way back to the hotel the youths again encountered the communicative policeman. Pointing in the direction of a round building similar to a windmill and supporting a signal-mast, he said, " That is what we call the Observatory, and it is used for signalling vessels coming into the harbor. It's one of the relics of the convict time; there was once a windmill there where they ground the grain for the convicts to eat, and when the wind didn't blow the prisoners had to work a treadmill in the lower part of the building. I used to know an old fellow who had often done his ' trick at the wheel;' he said he used to have to go it four hours on a stretch, and when through with his trick he was ready to lie down and take a rest. There isn't any part of the treadmill there now, as it was quietly stolen away by the boys, who sold the old iron for a good price." 


And finally, J.J. Knight in 1895 who provided more details including the fact that there were two treadmills contained in low sheds outside the windmill. It should be noted that Knight moved to Queensland in 1884, and his notes would have been based on second-hand accounts from unknown sources:


"Wigging " or, to use a more modern word, " slumming" work involved a penalty of either a whipping of twenty-five lashes or a position in the " lumber gang, "whose duty it was to give the necessary motion to the corn mill in what is now the Observatory by means of the treads. This mill was generally worked by twenty-five prisoners at a time, but when used as a special punishment sixteen were kept upon it for fourteen hours, with only the interval of release afforded by four being off at a time in succession. As may be imagined, the work was unduly hard, and especially so in hot weather, when men often fell off through sheer exhaustion. Low sheds were erected outside the tower, and in these were constructed two of those machines -" treads" - which are calculated to strike terror into the hearts of ordinary mortals. By means of a shaft these were connected with the mill in the tower, and thus-generally as a means of punishment-the motive power was provided by the feet of man. Those prisoners who were unfortunate enough to obtain an enforced acquaintance with the treads were marched up the hill between a guard of soldiers, and having done their turn, extending over several hours, were similarly escorted back to the barracks.”


The dimensions reported by Petrie align with a “Design for treadmill adapted for country districts” produced by the Colonial Architect in Sydney, in 1837. In this drawing the wheel has a diameter of approximately 1.6 meters with 24 steps. The length is 5.9 meters, or about 12 meters when two wheels are combined. The dimensions correspond nicely with the eyewitness accounts from Brisbane and I have used this design for the model.

Design for tread mill adopted for country districts. Colonial Architect, 1837.

A paper by Keith Preston (2013) on the treadmills of Van Diemen’s land provides more context for the Brisbane installation. The adoption of treadmills for prison use is attributed to the British civil engineer and millwright William Cubitt, with a first installation of his "Discipline Mill" 1819 leading to widespread adoption throughout the Empire over the following decades to “promote productive work and to overcome idleness” in his Majesty's prisons and penal settlements. Numerous mills were built in Australia, the West indies, Africa, Hong Kong and America. A good illustration of the standard “Cubitt Stepping Wheel” is the installation in Brixton Goal, which conformed to the emerging standard of a five to seven feet (1.35 to 2.15m) diameter and twenty-four steps. Cubitt wheels rotated at between 1.2 and 3.3 revolutions per minute.

Cubitt treadmill installed in Brixton gaol, 1821. The Brixton wheel provided the template for the first treadmill built in Australia for Carter's Barracks.

 An 1823 report on the Cubitt wheel installation in Brixton from provides further details on its operation:


The tread-wheel is set to work in the following manner. The party of prisoners ascend at one end by means of steps, and when the requisite number are ranged upon the Wheel, it commences its revolution. The effort, then, to each individual of the
party, is simply that of ascending an endless flight of steps, the combined weight of the prisoners acting upon every successive stepping-board, precisely as a stream of water upon the floatboards of a water-wheel. This operation is maintained without
intermission during the hours of labour, by the appointment of a certain portion of the class to relieve the party on the wheel. These changes are performed at regular intervals determined by signal, when tire prisoner at one end of the wheel descends for rest, another at the same moment ascends at the opposite extremity of the wheel, as represented in the frontispiece. By this method, the proper number of men on the wheel is continually kept up, and the work is equally apportioned to every man. The degree of labour to each prisoner in a given time is also determined with great precision, by regulating the proportion of working and resting men one to the other ; or, which amounts to the same thing, the relative proportion of those required to work the wheel with the whole number of the class ; thus, if ten out of fifteen men are appointed to be on the wheel, each man will have forty minutes labour, and twenty minutes rest in every hour.


The report also confirms that the Brixton mill had a fly-wheel to regulate torque and speed, however it is unclear whether this was a standard feature of Cubitt treadmills.


Australia’s first treadmill, based on the Brixton design, was erected in 1824 for Carter's Barracks in Sydney.  The first few treadmills were imported from England and local manufacturing of metal components started in 1825. A key limitation of the Cubitt wheel was the mehanical stress placed of the horizontal shaft on which the circular frames were mounted. Cast-iron shafts were expensive and prone to failure, and the local preference was therefore for timber shafts which necessitated the use of multiple wheels on one axis separated by support pedestals. The Tasmanian treadmills generally comprised multiple wheels of about eight to sixteen feet (2.5-5 meters) each. British mills were often divided into several separate wheels, such as the below example from the Bedford New House of Correction, 1821.

Cubitt treadwheel installation in the Bedford New House of Correction, 1821. Three wheels of approx. 1.5 meter diameter and 3.5 meter length, mounted on one shaft..

Preston concludes that Australian treadmills of the 1820s closely followed the Cubitt design standards. The mills were generally operated with “relays of one-third”, meaning that to thirds of the prisoners were on the wheel at any time with one third resting. The prisoners would step onto the wheel at one end, gradually move across to the other end and step off as their shift came to an end. Working days in Sydney were 10 hours in winter and 11 hours in summer.


Putting all of the information together; the eyewitness accounts, 1839 Brisbane maps, the Colonial Architect’s drawings and the Cubitt design standards, we arrive at the following specification for the Brisbane treadmill:


  • The mill was based on the Cubitt principles, with a 24-step wheel as confirmed by Walker. We can safely assume that it was a two-wheel mill on a single timber shaft separated by a support pedestal. This would explain the conflicting eyewitness accounts of the mill having one vs. two wheels.


  • The Colonial Architect’s design from 1837 has been assumed for the model. Each wheel has a length of 5.9 meters or about 12 meters in total. With a maximum of eight persons per wheel (see the renderings) this gives a total capacity of 16 persons for both wheels, again as reported by eyewitness accounts. It also aligns with Petrie’s reckoning of a “30-40” feet long wheel. I have used Petrie’s observation of 9-inch-wide treads, which work very well with the Colonial Architect’s wheel design.


  • As a side note, there is one report of a convict meeting his death after becoming tangled in the machinery. One may speculate that the poor soul, or rather his foot chains, became snared when moving across the separation from one wheel to the other, pulling him beneath the wheel under the combined weight of 15 men and the momentum of perhaps a ton of rotating timber and iron. A “bad way to go” as they say on Game of Thrones.


  • The model has the mill oriented precisely as drawn on the 1839 maps, in a north-westerly direction stretching into today’s Wickham Terrace. A quick site inspection confirms that this would be a convenient location as the ground is flat, with other directions sloping away from the mill. The location at which the shaft enters the windmill is precisely perpendicular to the windmill front which seems logical as the mill had two pairs of stones, one powered by the windmill (presumably to the left as viewed from the front door) and one powered by the treadmill (to the right). As described by Petrie the treadmill shaft would have been connected to “cogwheels” on the ground floor that drove a vertical shaft for the stones on the stone floor.


  • The model has a shed dimension of about 12x9 meters as per the 1839 map. As you can see, these dimensions provide good cover for the whole length of the wheel and also provides some shelter for resting convicts, overseers and supplies in this exposed location. There were no large trees on the top of the hill – they had all been cleared to improve airflow. I have assumed a simple timber frame construction with shingle roof as was the standard on other buildings.


Based on the eyewitness accounts and additional information provided by Preston we can also form an idea of the working shifts during normal operation. In the absence of detailed records, let’s assume that the Sydney working day of 10 hours in winter and 11 hours in summer also applied in Brisbane. Walker's observations confirm that the mid-day rest in Brisbane was 2 hours in winter and 3 hours in summer, giving a working day of 8 hrs in both seasons.


Under normal operation a chain gang or "lumber gang" of 25 prisoners were deployed to the mill, which conforms to the “relay of one-third” principle with 16 men on the wheel and 8 or 9 resting (possibly with the surplus 1 being the overseer assigned to counting the revolutions of the wheel). To start the cycle 16 convicts would strip off their shirts, climb the "five steps” and grasp the handrail as described by Petrie. An iron bolt at the end was pulled by the overseer and the wheel was set in motion, again as described by Petrie. Walker noted that the wheel performed 160 revolutions from the time at which a person stepped on until he stepped off. With 16 convicts on the wheel this would require a “shuffle” of convicts every 10 revolutions or about every 5 minutes assuming the Cubitt average of 2 rpm. Prisoners would take a total of 240 steps before the next shuffle, and 3,840 steps between stepping on and off the wheel as confirmed by Walker.  During normal operation a convict would be “stepping” on the wheel for a total of about 5 hrs and 20 minutes (480 minutes X 2/3) each working day. During this time, he would take 15,000 steps of 220mm each, equivalent to a 3,300-meter climb.


However, during “special punishment” the working day extended to 14 hrs and the relief team was reduced to four, or a relay of one-fifth. This gives a working day of 11 hrs and a total “stepping” time of 8 hours and 50 minutes (660 minutes X 4/5). During this time the convict would take about 25,000 steps, equivalent of a 5,500-meter climb. We can conclude that the “special punishment” regime came with a 65% increase in effort compared to normal operation.


“Special Punishments” in Brisbane appear to have exceeded the daily maximum ascent of 3,660 meters which was prescribed by the British Society for the Improvement of Prison Discipline. With this in mind, the eyewitness accounts of timber treads being soaked in sweat and prisoners falling off the wheel in a stupor appear entirely plausible.

"No more tricks at the wheel". Ex-Moreton Bay convict reminisces in "Boy Travellers in Australasia", 1889.

If you know of any information regarding the windmill or treadmill that has not been referenced here I would be very keen to hear about it ( For more information on the Moreton Bay penal settlement and early colonial history be sure to visit the Commissariat Store and museum - a wonderful family destination which also holds some handsome models of other Brisbane convict-era buildings.



Key sources:


Bowerman Sketches: Bowerman, Henry Boucher 1831, Henry Boucher Bowerman View of Brisbane [Work of Art], 1831-1835. 


Map: Layout of Brisbane Town, Moreton Bay. 1839. Queensland State Archives Item ID659605, Architectural plans.


Brisbane City Council, 1949. The Observatory in 1949, east elevation, section and ground floor plan. Sketch by T. A. Perry, reproduced in Steele, J. G. (1975). Brisbane Town in convict days, 1824-1842. St. Lucia, Queensland University of Queensland Press


Hogan, Janet & National Trust of Queensland (1978). The windmill of Brisbane Town : a study of the social and structural history of the Windmill Building, Wickham Terrace, Brisbane. National Trust of Queensland


Unidentified (1892). Observatory at the top of the old Windmill in Brisbane, ca. 1892. John Oxley Library, State Library of Queensland


Unidentified, unknown year. Old Windmill; Brisbane Observatory - 226 Wickham Terrace - Spring Hill. Brisbane City Council, BCC-B54-34982.


Marquis-Kyle, Peter. Brisbane's Windmill an Account of the Conservation Process. Retreived 29.06.2016 from: 


Hall, Jay; Department of Anthropology & Sociology, The University of Queensland, Brisbane, QLD 4072 & Prangnell, Jonathan; Department of Anthropology & Sociology, The University of Queensland, Brisbane, QLD 4072 & David, Bruno; Department of Anthropology & Sociology, The University of Queensland, Brisbane, QLD 4072 (2009-02-03). The Tower Mill: An archaeological excavation of Queensland's oldest extant building. School of Social Science, The University of Queensland


Notes regarding John Oseland. Retrived 25.06.2016 from convicts/oseland/john/70669.


Backhouse, James (1843). A narrative of a visit to the Australian colonies. Hamilton, Adams, London


Backhouse, James The life and labours of George Washington Walker, of Hobart Town, Tasmania. A. W. Bennett; York : Thomas Brady, London


Ross, William (1836). The fell tyrant, or, The suffering convict : showing the horrid and dreadful suffering of the convicts of Norfolk Island and Moreton Bay, our two penal settlements in New South Wales, with the life of the author William R...S. Ward, London


Petrie, Tom & Petrie, Constance Campbell, 1873-1926 (2013). Tom Petrie's reminiscences of early Queensland : (dating from 1837). Salisbury, Brisbane Watson Ferguson & Company


Eight years' resident (1876). The queen of the colonies : or, Queensland as I knew it. Sampson Low, Marston, Searle & Rivington, London


Knox, Thomas W. (Thomas Wallace) (1889). The boy travellers in Australasia : adventures of two youths in a journey to the Sandwich, Marquesas, Society, Samoan, and Feejee Islands, and through the colonies of New Zealand, New South Wales, Queensland, Victoria, Tasmania, and South Australia. Harper & Brothers, New York


Knight, J. J & Petrie, John (1895). In the early days : history and incident of pioneer Queensland : with dictionary of dates in chronological order (2nd ed). Sapsford & Co, Brisbane


Treadmill design  adapted for country districts, 1837, NRS 4334, Designs of Public Buildings, 1837, [X694], Reel 2660


Preston, Keith (2013). Prison treadmills in Van Diemen's land: Design, construction and operation, 1828 to 1856. Papers and Proceedings: Tasmanian Historical Research Association 
Volume 60 Issue 2 (Aug 2013).


Society for the Diffusion of Knowledge Upon the Punishment of Death and the Improvement of Prison Discipline (London) Description of the tread mill invented by Mr. William Cubitt, of Ipswich, for the employment of prisoners, and recommended by the Society for the improvement of prison discipline, &c. Published by the Committee, London


Plans for treadmill at Bedford New House of Correction. Retreived 18.06.2016



Aerial photos by Google Earth and Queensland Globe.



Detailed references are available on request. The buildings were modelled in SketchUp and rendered with Indigo 4. All images in this article are Version 2 renderings, published 13 June 2017.

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