FIRE ENGINES AT LEADHILLS AND WANLOCKHEAD

INTRODUCTION

In 1786, William Symington adapted a Watt engine on the Margaret mine at Wanlockhead to his own 1787 patent specifications. The modified engine performed better than the original. The first atmospheric pumping engine built to William Symington's 1787 patent specification was erected in 1790 on the Bay mine at Wanlockhead. In 1792, he designed and built a pumping engine for the Humby mine at Leadhills. No plans of the Bay engine have survived, but William kept drawings of the engine house at the Humby mine. 

Lead mining had been conducted high in the Lowther hills of Southern Lanarkshire for centuries. Pumping engines were required to clear water from the mines which were sunk to great depths and which were subject to inundation. The early pumping engines at Leadhills and Wanlockhead were powered by water wheels. William's father, John Symington, and his elder brother George were employed as carpenters or mechanics on the Leadhills mines and would have been involved in the construction and maintenance of those pumping engines. The capricious supply of the surface water which was required to power the water wheels induced the Wanlockhead Mining Company to consider a steam engine to power the pumps. As reported in the Wanlockhead Mines Journal of 1757: "The workings must always be precarious and uncertain because the great rains and snows in the winter time so swell the springs the engines cannot manage them, while in the summer season the water is so scanty it is not enough to turn the wheels."[1]

The Wanlockhead Mining Company ordered an engine from Boulton and Watt for the Margaret mine. This engine, the first steam engine to be built at Wanlockhead, was erected in 1779 under the direction of William Murdoch, the inventor, engineer and pioneer of gas lighting. Boulton wrote to the manager of the Wanlockhead mines about Murdoch: "He hath a good deal of experience in our engines and is capable of putting your people to rights in any matter they may not understand, & we doubt not that he will acquit himself to your & to our satisfaction, as he is a man we have a good opinion of. Pray don't keep him any longer than necessary as we want him in Cornwall." Watt wrote that he was "a very sober, ingenious young man, who has a good deal of experience under us in putting engines together and knows all the little niceties, the omission of which might cause a bad performance in your engine."

The engine for the Margaret mine was erected at Mennock Hass, a narrow pass leading from Mennock Water into Wanlockhead. Under Murdoch's supervision, William Symington's elder brother George was engaged to erect a 36 inch Watt engine. George had already gained experience with steam engine construction the previous year when Boulton and Watt seconded him to work on an engine at Torryburn in Fifeshire. 

Murdoch arrived at Wanlockhead on 28 March 1779; the engine was set going by 8 May 1779. Murdoch departed Wanlockhead on 24 June with the observation "tis the most regular engine he ever saw." [2]

In 1786, George Symington built a larger replacement Watt engine for the Margaret mine with a 55 inch diameter cylinder and 8 foot stroke. [3] George retained Watt's scale drawings for the 1786 engine which he passed on to William who patented his "STEAM ENGINE, ON PRINCIPLES ENTIRELY NEW" in 1787. William's plans which illustrate his 1787 patent are broadly based on the Watt drawings. 

WILLIAM SYMINGTON'S EXPERIMENTAL ENGINE 1786

In 1786, William Symington modified the original 36 inch Watt engine on the Margaret mine, according to the design of his patented engine, based "On Principles Entirely New." The cylinder was re-bored by Carron Company, and was encased by a spiral duct which directed hot gas from the boiler around the cylinder. The rebored cylinder and other new parts for the modified engine are listed in the Carron Company invoice to Gilbert Meason, manager of the Mining Company, dated 13 October 1787. [4] It appears that he also built a model engine at about the time he modified the Margaret Vein engine. (Rankine Biography: Letter John Taylor to Thomas Gilbert 24 September 1786). Harvey and Downs-Rose published a sketch of the model engine, reproduced below, which was drawn by "one of James Watt's erectors" in October 1787 but the source and the author of the sketch are not identified. [5]

[1] Wanlockhead Mines Journals, Journal Number 1, 1757, page 49 Hornel Library, Kirkcudbright

[2] BRL Boulton & Watt Collection MS3147/3/511

[3] Downs-Rose, G., Draining The Wanlockhead Lead Mines A Note on the Introduction and Use of Hydraulic Pumping Engines, Transactions of the Dumfriesshire and Galloway Natural History and Antiquarian Society, Third Series. Volume LIX 1984 pages 70-81

[4] SRO GD58 4/19/20

[5] Harvey, W.S. and Downs-Rose, G., William Symington Inventor and Engine Builder London 1980 Page 25

William Symington published the following advertisement, detailing the performance of the converted engine, in the Newcastle Courant of 24 January 1789:

NEW PATENT STEAM ENGINE.

     WILLIAM SYMINGTON, having completed his Experiments upon his new, improved Steam Engine, and last summer having erected one, with a 36 inch cylinder, upon the Lead Mines at Wanlockhead, in Scotland, finds its properties to be as follows

     1st, Acting by the pressure of the atmosphere, it works with a power equal to 12 lib. For each square inch contained in the pistons and, when thus loaded, can with ease perform 14 strokes, each stroke 8 feet long, per minute.

     2d, By a new, but simple, method of condensation, this power is produced, without alternately heating and cooling the cylinder, as in the old Engine.

     3d, Its consumption of Coal is as little as that of any other steam Engine whatever.

     4th, Being little more complicated than the common Fire Engine, it can be as easily managed; and, at as little expence, kept in repair.

     5th, From the nature of its construction, Engines, erected on the principles of the old one, can be converted to those of the above plan, at little more than the expence of a small addition to the bottom of their present cylinders.

     6th, Being aided by this new and very advantageous method of applying the power of the Engine to rotatory motions, it can with more advantage and conveniency be adapted for the purposes of drawing Coals from deep works, grinding, sawing, &c. than any other Steam Engine yet known to the public. 

     Hence the Inventor recommends it to the attention of the Gentlemen who have occasion to use such Machines, as, with confidence, he can assure them that this Engine possesses very great advantages over any other yet in use, and, when adopted, will shew itself to be of public utility. 

     Letters addressed to "Mr William Symington, Engineer, Wanlockhead, by Edinburgh," will be duly attended to.

                                                                     THE BAY MINE ENGINE AT WANLOCKHEAD 1790

William designed and built the pumping engine which was erected on the Bay mine at Wanlockhead in 1790. The name "Bay" was a contraction of "Botany Bay," which was then the popular name for the mine. The Bay mine was situated in Whyte's Cleuch, a shallow valley on the north-western slope of the Wanlock Dod, a prominent rounded hill to the north of the village. The footings for the Bay engine can still be seen in that elevated valley. The site of the mine is now marked by a memorial plaque on a stone pillar, overlooking the Meadowfoot cemetery (Map reference 55 deg 24' 15" N 3 deg 47' 23" W).

The steam engine for the Bay mine was built to the specifications of William Symington's 1787 patent for “A STEAM ENGINE, ON PRINCIPLES ENTIRELY NEW,” and was the first pumping engine he designed and built. The engine parts for the Bay engine, also known as the Whytes Cleuch engine, were ordered from Carron Company in 1789 for the Wanlockhead Mining Company. The Carron Company invoice, dated 31 October 1789, to Gilbert Meason Esq., the Mining Company manager, provides a comprehensive list of the engine components, including the cylinder, two pistons and piston rods.[1]  The engine's cylinder measured 44 inches in diameter, with a stroke of eight feet. The cylinder weighed over four and a half tons and required a team of eight horses to haul it on a large carriage from Carron to Wanlockhead. [2] [3]

From their field work, Harvey and Downs-Rose calculated the length of the massive overhead beam was 22 feet.[4] The dimensions of the engine house were replicated in the engine house later constructed for the Humby mine in Leadhills - the beam wall was six feet thick (see below). There were at least two boilers. The Bay engine was completed and working well by September 1790. [5] Entries in the Wanlockhead Mines Journal record several stoppages brought about by a lack of injection water due to drought or frost. From 19 to 30 January 1795, a thorough repair of the engine was undertaken, including the fitting of a new "nozel" with a low valve and other new valves fitted in the "face." A new piston was fitted in September 1795. A pipe burst in the "East Boiler". [6]

The Bay mine engine was dismantled in 1799 and Carron Company re-bored the cylinder which was employed in a new engine which was assembled in 1800 on the Beltongrain vein, on the boundary between Wanlockhead and Leadhills. 

By 1809, the original Bay mine engine house was still in use and in good order but a new engine was required. The following entry is from the day book of the Wanlockhead Mining Company for June 1809: "The old Engine house of Symingtons Engine answers, and the machinery boilers & pumps of a new Engine are only necessary" and, " The Manager recommends that the Carron Company should be employed to make the Engine and that Wm. and Geo. Symington who reside at Falkirk & were formerly in the Companys service as engineers should inspect the materials and workmanship so as give the Company a more perfect Engine…" [7]

William Symington's original working drawings for the Bay mine engine have not survived. However, the form of this engine and engine house may be inferred from the very nice coloured plans which supplement and illustrate his 1787 patent submission.  The dimensions of the Bay mine engine were later replicated in the engine house which was built for the Humby mine at leadhills.

The celebrated engineer John Rennie closely examined the recently erected engine on the Bay mine in June 1791. He sketched the mechanism in his notebook. Rennie was an independent engineer with a wide range of interests. Best known for his work on canals, docks and bridges, Rennie had started out as a millwright and mechanical engineer. He had entered a loose business agreement with Boulton and Watt and was acting as Watt's agent in London, assisting customers and performing engine repairs and maintenance. Rennie travelled widely and, in a series of pocket notebooks, he kept detailed notes on a wide range of engineering subjects which had taken his interest. Rennie reported his observations on Symington's engine at Wanlockhead to James Watt who was keen to identify engine builders who may have infringed his patent. (See section on Pirate Engines). Rennie's notebooks are held in the National Library of Scotland at Edinburgh.

[1] SRO GD58 4/19/22

[2] SRO GD58 6/1/23 Carron to Meason 8 March 1789

[3] SRO GD58 6/1/25 Carron to Meason 8 July 1789

[4] Harvey, W. and Downs-Rose, G., The Bay Mine Wanlockhead Scotland, British Mining No. 2, Monograph of the Northern Mine Research Society 1976

[5] SRO GD58 6/1/25 Carron to Meason 14 September 1790

[6] Harvey, W. and Downs-Rose, G., Mr. Symington's Improved atmospheric Engine Early Steam Engines at Wanlockhead, Dumfriesshire. Paper presented to the Newcomen Society at the Science Museum, London on 13 March, 1974

[7] SRO RH4/116/2 Wanlockhead Mining Company Day book 1801-1811

JOHN RENNIE'S 1791 DESCRIPTION OF WILLIAM SYMINGTON'S ENGINE AT WANLOCKHEAD 

The following is my transcription from Rennie's notebook: [1]

Symingtons Engine

There is a new Steam Engine Erected at Wanlockhead on Symingtons plan. 

It has a Cylinder of 48 Inches diar & a 8 feet Stroke

Pumping 14 Inches –sunk 12 fathoms

This engine works entirely by the weight of the atmosphere & at the Time I saw it was working a Catarract at 1 ½ Strcks per minute. They never had been able to make any expt on her working & consumption of coals as the pit they were sinking was not nearly arrived at its depth.

[1] NLS GB233/MS19837 Pages 23 to 27

AB is the Engine Cylinder

C is the Piston attached to the end of the working beam

D is a Piston in the bottom of the cylinder & has a rod DE passing through the bottom of the cylinder in a stuffing box this Rod has a beam EG moveable on a centre G & its extremity is loaded with weights so as to balance the piston & keep it always up to D when there is no steam acting against it. H is a steam nozzle & valve. I is an exhaustion nozzle & Valve K is a kind of Reservoir that communicates both with the exhaustion nozzle & the bottom of the cylinder.

M is a valve opening outwards in the Condenser L & is Kept close(d) by its own weight & that of the external air.

The working of the Engine is thus-

The Steam is admitted by the Steam valve H

The Steam passes into the Cylinder - raises the Piston C- to the top viz - 8 feet - depresses the piston D - one foot - so that 9 feet of the Cylinder is filled with Steam to perform an 8 feet stroke

When the Pistons has got at the extremity of their strokes the Steam valve H is shut & the exhaustion valve I is opened

The Injection valve is at the same time opened which admits the water into the reservoir K The steam rushing in there is exhausted only in a certain degree. But when this partial exhaustion is made the Piston C descends by the pressure of the atmosphere & the Piston D is raised by the weight at the at the extremity of the beam EG which of consequence makes a vacuum in the bottom of the Cylinder which answers the end of an Air Pump.

Thus the stroke being repeated. The Condensed Steam is pressed out by the valve M & so on alternately.

If this Engine is compared with one of Boulton & Watts independent of the disadvantages arising from using the atmosphere as the moving power (which by the by they said produced 12 lb. per square inch effective power). There is a waste of steam lost each stroke by the motion of the Lower Piston- which is exactly 1/8 of the Power of this Engine.

The following description of the 44 inch Bay engine comes from an unnamed correspondent and is to be found in the Boulton and Watt Archive at Birmingham, filed under the category of "Pirate Engines": [1]

Descriptn of Symington's Engine 

dated Leadhills 25 May 1791

            We are now pretty well satisfied the improvement of the Fire Engine found out by our neighbour Mr. Symington will ans.r the Expectation he & his friends form from it.

            The Experiment which was tried upon Messrs. B.&W. Engine here gave them so much encouragement that the mining Gentlemen in whose employment he was at WanlockHead have erected a new one on Symington's plan, executed entirely by his directions. 

            The Cylinder was 44 I. diar. & the working Barrell is 14 I. diar. & the depth to be lifted is 40 fathoms- having met with the water in this shaft they are now sinking with the Engine which at present draws 37 fathoms, burning no more than 10 of our loads of coal in 24 Hours- Each load being 12 Dutch stones, equal to 1.2.16 and makes 7 strokes in 2 Minutes. On calculation I think you will find that 40 fathoms of a 14I. Pump will be equal to 10 lbs pI. of the Cylinder- The Model which he first made worked 11 lbs to the Inch & we have no doubt but this Engine w.d exceed that so much that they may go 5 or 6 fathoms deeper than they first intended- I will endeavour to give you what Idea I can of the Engine- The Cylinder is open at the Top like the old Engines  & the Piston works without any water upon it, having a very simple Contrivance, which seems to ansr. The purpose of water, by means of which if the Piston is not tight at any time it draws steam & not air- The Cylinder is 11 feet long; in the Bottom of which is a Piston that he calls the Medium, making a Partition between the steam & the cold water- The Cylinder Bottom is immersed in cold water for a few Inches covering 2 valves in the Bottom Flanch of the Cylinder, which at the Front of the Cylinder is produced for 18 or 20 Inches in order to admit steam when the steam valve is open & allows the Piston to ascend- The Elasticity of the steam in the Cylinder presses down the medium 6 or 8 Inches, which forces out at the above valves the Injection Water & condensed steam of the preceding stroke-The water that in the old Engine feeds the Boiler being thus made almost cold, by mixing with the water in which the bottom of the Cylinder stands, he is under the Necessity of lifting it with a small Pump & carrying it thro' the flues to be heated & then rises up into his cistern to feed the Boiler- There is a spiral flue of 14 I. round the Cylinder by which can be admitted either part or the whole of the heat of the fire after it has passed round the Boiler-I observe that the Cylinder is kept so hot that little or no Condensation appears in it between the strokes, even at the interval of the stroke

            The same mining Company have an……….

3&4 years ago, the Cylinder of which is 55 Inches Diar & they consider that Burden on the 2 Engines equal, the Pump being 12 I. diar. & the depth 56 fathoms, the stroke of both Engines 8 feet-

            When Symington's Engine was set to work B&W's burning 15 loads of Coals in 12 Hours & Symington's was at the same number of strokes, the water being turned into the shaft for that purpose, & it did not burn quite 7 Loads, B&W's is in good Condition.

            I did not believe there to be so much difference till I saw the size of the Fire on the Grate, the smallness of which surpris'd me.

            If I understand right I think that no more steam is wasted when the Engine is minded properly than what it takes to fill the Cylinder every stroke.

LeadHills 25 May 1791

The above letter is filed together with the following commentary which would have been prepared by, or on behalf of, William Symington himself:

Mr Symington's improved Steam engine mentioned in the printed paper, works by the pressure of the atmosphere, having an open Cylinder, as in the old Engine. The principal improvement is in the condensation of the Steam by a new and simple method. This is effected by introducing a Second Piston into the Cylinder which moves betwixt the Steam passage and the bottom; & below which the steam is condensed. Its uses are to prevent the injection water from jeting high into the Cylinder, to prevent the steam from being condensed when filling the Cylinder, by coming in contact with the injection water thrown in the preceding stroke, & by its descent, to expel that water thro a valve placed for that purpose. The motions of this piston are produced without in the least degree extracting from the power of the Engine, and experience hath shewn it to be the most compleat method of producing a vacuum adapted in the Steam Engine; for, when loaded with 12 lb upon each square in in the are (sic) of the piston, this Engine can with ease perform fourteen eight feet strokes per minute, upon a consumption of coal as little as that of the most improved Engine in use. It remedies the imperfection of the Old Engine, & as neither air nor hot water pumps are used, almost equal in Simplicity which renders it easily managed and kept in repair.

Mr. Symington, the Inventor of this Engine, having been equally attentive to saving of Fire, and increase of Power, obtained these Ends by a simple Construction, and Method of condensing the Steam, so that at each Stroke as perfect a Vacuum is produced as the Nature of Steam and Water will admit, and any Person acquainted with the common old Fire Engine may easily manage and keep this one in Repair. By a comparative Trial betwixt Mr. Watt's and this Engine, at Wanlockhead Lead Mines, in Scotland, in the Course of las Summer, it appeared, both Engines having a Cylinder 36 Inches diameter; consuming the same quantity of Coal, and making an equal Number of Eight Strokes per Minute, Mr. Symington's wrought with a Power equal to12 lib. For each Square Inch contained in the Area of the Piston; whilst Mr. Watt's wrought with a Power equal only to 9 ½ lib. Per Square Inch; that is to say, his Engine did at least one fifth more Work than Mr. Watt's, upon the same Consumption of Fuel.

Having secured his property by Patent, he offers the Use of this much Improved Engine, and its various Application by a new and advantageous rotatory Motion, to all those who are concerned in Mines, Stamps, Water Works, Draining of Fens & Lakes, Grist Mills, Saw Mills, Breweries, or other Manufactories which require great Mechanical Power. He intends to give, make and put it up, upon most reasonable Terms.

KEY REFERENCES

Harvey, W. and Downs-Rose, G., Mr. Symington's Improved atmospheric Engine Early Steam Engines at Wanlockhead, Dumfriesshire. Paper presented to the Newcomen Society at the Science Museum, London on 13 March, 1974

Harvey, W.S. and Downs-Rose, G., Mr. Symington's Improved atmospheric Engine, Transactions of the Newcomen Society Volume 46, 1973-1974, pages 27-32 (Extract)

Harvey, W. and Downs-Rose, G., The Bay Mine Wanlockhead Scotland, British Mining No. 2, Monograph of the Northern Mine Research Society 1976

Harvey, W.S. and Downs-Rose, G., William Symington Inventor and Engine Builder London 1980

[1] BRL Boulton and Watt Archive MS 3147/5/1353b

THE HUMBY MINE ENGINE AT LEADHILLS 1792-1799

The Hope family, founders of Hopetoun House near Edinburgh, had acquired the lands of Leadhills through the marriage of Sir James Hope (1614-1661) to the daughter of Robert Foulis of Leadhills. In 1730, James Stirling, the mathematician, was appointed as the manager of the Scots Mines Company, which had been founded by royal charter in 1729.  He died in 1770. He was succeeded as manager by his nephew, Archibald Stirling. This was the era of John and George Symington who were then employed as engineers on the Leadhills mines. In 1782 a partnership of London interests, headed by Alexander Popham and trading as the Leadhills Mining Company, took over operations on Minehill. Popham bought the first steam engine to work at Leadhills, but his company was unprofitable and ceased operations in 1805.

THE FIRST STEAM ENGINE AT LEADHILLS

The first steam engine to be erected on a Leadhills mine was a second-hand Watt engine which was sourced from the White Gritt mine in Shropshire. That engine had been disassembled by Robert Muir whom Boulton and Watt had employed as an engine erector. In 1788 the Leadhills MiningCompany invited Muir to reassemble the engine for a mine at Minehill at Leadhills. Muir made a poor job of it: "the cylinder was too far into the house and the beam even further than the cylinder." [1] As a consequence, "Mr Symington" was engaged to "put her to rights" [2] That reference would relate to William Symington who was then actively engaged in engine design and construction at Wanlockhead.

THE HUMBY MINE ENGINE

The engine on the Humby Vein was the second steam engine to be built at Leadhills. The Humby vein was part of the Susannah vein complex, situated to the north-west of the settlement at Leadhills.

The State of the Works summary in the Leadhills Mining Journal for 1 January 1791 reported that the Grips level on the Humby Vein, had yielded "a considerable quantity of ore above level and promises to yield much more there but the prospect of ore below level here is greater than above tho the water appears to become heavy in going down upon it…" [3]  In the 1 January 1792 review of the state of the Humby vein, the report read: "But our greatest hopes here is for One under level by an Engine that must draw a very great feed of water" [4]

A pumping engine was required to enable mining of deeper reaches of the Humby vein. In 1791 the directors of the Scots Mines Company obtained an estimate to erect a water wheel on the Humby mine. The estimate for the timber required for a wheel measuring 30 feet in diameter and 30 inches broad and the frame was in excess of £117. [5] They decided that a steam engine was a better option and instructed the manager, Archibald Stirling, to "look at Mr. Watt's and Mr. Symington's engines to see which has given preference." Stirling commenced negotiations with Boulton and Watt. In February 1792, James Watt provided Stirling with an estimate for an engine with a 53 inch cylinder to pump the Humby vein. [6] In May 1792 Watt produced working drawings for the proposed engine. However, after considerable vacillation, Stirling opted for an engine to William Symington's design as "the most proper to be erected upon Humby Vein" [7] and engaged William Symington to build the engine.  The Humby engine was designed to pump more than 72 gallons per minute from thirty fathoms below the drainage level. [8]  The engine parts were ordered from Carron Company in June 1792 and the engine was working by 1794. [9] 

In August 1794, 16 men were employed in "Sinking the Steam engine Sump in Humby 13 ½ fathoms under level." [10]

By March 1795 the Humby mine was a hive of activity, with a total of 80 men employed in driving and sinking and in raising ore.

The report on the state of the works at the Humby vein for 1 January 1796 gives a graphic description of the difficult working conditions imposed by inundation of the Humby mine. The Symington steam engine had performed well but it had become impossible to contain the inundation which was far more than had been anticipated. The volume of water gushing into the mine made it impossible to sink the shaft more than 13 ½ fathoms below the Grips level. The engine had been made more powerful than originally envisaged and was "still fully able for drawing all the water which is frequently above a hundred feet in the minute But that quantity of water rushing in jets through the Rock from every quarter upon the Workmen and the same time covering the part they are working in from 12 to 18 inches deep renders it extremely difficult and barely practicable for them to proceed with the sinking…"  It was first proposed to sink the Humby mine to 20 fathoms. However, the rock was so hard that gunpowder would have been required yet the amount of water made this impracticable. [11] In July 1796, 24 men were employed in raising ore from the Humby vein but by November 1797, only eight men were employed. By April 1798, the mining of the Humby vein had come to an end. In the report of the state of the works on the Humby Vein dated 1 January 1800, it was stated that all the available ore had been taken from the above level and all that could be reached from the below level had been wrought out and that the works had been relinquished. [12]

The Humby engine was dismantled. [13] The engine plans have not survived but William Symington kept possession of Watt's original plans for the engine house and boiler house.

KEY REFERENCES

Harvey, W. S., Pumping Engines on the Leadhills Mines, British Mining Number 19 1980-1982 pages 5-14 

Harvey, W. S. and Downs-Rose, G., The First Steam Engine on the Leadhills, Mines British Mining Number 28 NMRS 1985 pages 46-47

[1] Harvey, W. S., Pumping Engines on the Leadhills Mines, British Mining No. 19 1980-1982 pages 5-14

[2] Harvey, W. S., Pumping Engines on the Leadhills Mines, British Mining No. 19 1980-1982 pages 5-14

[3] Leadhills Library Mining Journal Book 7 LML 011 1790-1795 page 50 

[4] Ibid page 75 

[5] Ibid pages 197-198 

[6] SRO TD74/26/2 Watt to Stirling 24 February 1792

[7] Garden MSS Bundle 17 21 April 1792

[8] Harvey, W. S., Pumping Engines at the Leadhills Mines British Mining No. 19, NMRS, pages 5-14, 1982

[9] Carron Company Invoices to Archibald Stirling 23 August and 30 October 1792; 31 January, 14 February, 17 March and 29 April 1793 SRO GD58 4/19/21 30 October 1792 to "Scots Mine Company Leadhills" invoice for cylinder and cylinder bottom; 31 January 1793 to "The Scotch Mine Company Leadhills" for numerous other components

[10] Leadhills Mining Journal Book 7 LML 011 page 173 

[11] Ibid pages 189 and 190

[12] Leadhills Library Mining Journal book 9 LML 013 page 48

[13] Harvey, W. S., Pumping Engines at the Leadhills Mines British Mining No. 19, NMRS, pages 5-14, 1982

THE ENGINE AND BOILER HOUSES ON THE HUMBY MINE

Built to accommodate an engine of gargantuan proportions, the engine house on the Humby Vein once stood as a massive stone sentinel, dominating the northern approach to the village of Leadhills. The imposing three story stone edifice would have resembled a medieval stronghold. The engine house was constructed to withstand the ravages of climate and time, yet barely a trace remains. Beam engine houses have now all but disappeared from Scotland's landscape. The derelict engine house at Thornton, Fifeshire, is a rare survivor from the late eighteenth century.  

This drawing of the engine house is copied from the original Boulton and Watt plan which William Symington retained. His son brought some of those plans to Australia in 1855.

William Symington managed to retain the plans for Watt's proposed engine and boiler houses for the Humby mine which were drawn in 1792. He also kept Watt's drawings for the 1785 engine for the Margaret mine at Wanlockhead but no plans for his Humby mine engine have survived.

The Humby mine engine house was reported to be "equal in size to the Botany Bay engine at Wanlockhead."  The main wall was built of hewn stone, six feet thick at the base and fifty feet high. [1]

The three-storied engine house had a gable roof. The engine, supported in a timber frame, was at the first level. The top of the cylinder was at the middle chamber of the engine house and the upper chamber, known as the bob loft, accommodated the massive overhead oak beam. The bob wall was strongly built to withstand the weight and vibration of the enormous timber beam which it supported. For structural integrity, the openings in the bob wall were kept relatively narrow. The boiler house, which was attached to the side of the engine house, had a pitched roof. The stack or chimney is not depicted in the Watt plans. However, it may be assumed that the stack was square in section. Watt's plans for his 1785 Wanlockhead engine and William Symington's 1787 patent drawings each reveal a square stack.

In his field work, W.S. Harvey found an indistinct residue of cinders which is all that remains to mark the site of this once massive and impressive engine and boiler house (O.S. map reference NS 883159; 55 deg 25' 27" N 3 deg 46' 11" W).

WATT PLANS FOR HIS PROPOSED HUMBY ENGINE AND BOILER HOUSE

Boulton and Watt prepared plans for the Humby mine engine in 1792. However, the Scots Mines Company offered the contract for the engine to Symington who kept some or all of Watt's working drawings. The Boulton and Watt plans for the front gable or bob wall and side elevation for the Humby engine house have survived. Three plans were retained by William Symington's son who took them to Australia when he emigrated in 1855. These plans are tattered and water-stained:

1. A drawing headed "Front Section of Humby Vein Engine house 10 May 1792," 25cm x 43cm; no watermark. This drawing has been lost.

2. An end elevation of an engine house and attached boiler house, inscribed "East view of Boiler house" and "Seat of Boiler house" 38cm x 47 cm; no watermark; inscribed on the reverse side "Watt's".

3. Boulton and Watt plan of a three-story engine house. Being a reverse or mirror image, this copy would have been produced on Watt's document copying press which he patented in 1780. [2]

[1] Leadhills Miners Library, Journal 1790-1795

[2] Patent Number 1244 14th February 1780

NOTES ON THE CONSTRUCTION AND DIMENSIONS OF THE HUMBY MINE ENGINE HOUSE

The engine house extended to a height of 50 feet at the ridge of the gable roof; the width of the building measured about 22 feet at the base; the side walls were 39 feet high. The engine house comprised a basement, ground, first and second floors, and the bob loft which housed the overhead wooden beam or "bob". The rooms were 15 feet wide; the room on the first floor was 9 feet high; the height of the second-floor room was 10 feet. The bob wall was the sturdiest, built to withstand the stresses and vibrations from the beam. The thickness of the side walls measured 3 foot 6 inches at the base, tapering to 3 feet, 2 foot 6 inches, and then to 2 feet at the top. There were three openings in the bob wall: a doorway at ground level measuring 6 feet wide and 7 feet high; a middle opening measuring 6 feet by 9 feet, and the upper opening for the beam which was 6 feet wide and 10 feet high.

The boiler house, built as a lean-to structure abutting the engine house, measured 25 feet 3 inches in length and 13 feet in width. The internal width of the boiler room was 11 feet. The side wall of the boiler house was 2 foot 6 inches thick at the base, narrowing to 2 feet 2 inches and to 1 foot 10 inches at the top; this wall was 18 feet 3 inches high.  The doorway to the boiler room was 7 feet 6 inches high and 4 feet wide. 

The chimney stack is not represented in these plans but would have been square in section, as shown in plan number 4 for the 1785 Watt engine at Wanlockhead and in William Symington's drawings which illustrate his 1787 patent engine.

THE ENGINE HOUSE FOR WATT'S 1785 PUMPING ENGINE AT WANLOCKHEAD

William Symington managed to retain important working working drawings which were prepared by Boulton and Watt for their 1785 Wanlockhead engine. [1] Duplicates are held in the Boulton and Watt archive at Birmingham. [2] The engine house is well described in Drawing No. 1 General Section of Wanlockhead Engine 1/3 inch to the foot and No. 4 Front View:

The engine cylinder was 55 inches diameter with an 8-foot stroke; the oak beam was 20 feet long, 5 feet wide and 2 foot 4 inches thick. The hemispheric boiler measured 13 foot 6 inches by 6 foot six inches.

[1] I donated these drawings to the Melbourne Museum

[2] BRL B&W Collection Engine Drawings Main series MS3147/5/558

Dimensions of Watt's 1785 Wanlockhead Engine House

The height of the masonry end walls to the ridge of the gable roof was 51 feet; the side walls were 41 feet high. At ground level, the front of the engine house was 21 feet wide, the side walls measuring 24 feet.

The bob wall was 5ft. 3 inches thick at base, reducing to 4 ft. 9 inches under the beam. The corresponding measurements for the opposite wall were 3 feet at the base, narrowing to 2 foot 6 inches. The side walls were 3 foot six inches thick at the base, narrowing to 3 feet, then to 2 foot 6 inches at the top.

The engine rooms measured 14 feet by 16 feet inside. The room on the first floor which contained the cylinder was 9 feet high. The height of room at the second floor 13 feet; the capped cylinder top protruded through the floor.

PLANS FOR WILLIAM SYMINGTON'S 1787 PATENT SPECIFICATION

Notes on the engine house.

The detailed drawings which illustrate William Symington's 1787 patent specification show the structure of the engine house and boiler house which may have been adapted for the Symington engines on the Bay and Humby mines.

From the drawings which illustrate William Symington's 1787 patent number 1610 for A STEAM ENGINE, ON PRINCIPLES ENTIRELY NEW.” 

The cylinder had a 50 inch bore and a stroke of 8 feet. The overhead beam measured 21 feet 6 inches long and 4 feet 3inches wide. The engine room was 20 feet long.

The engine house depicted was 29 feet long, with a height of 44 feet to the ridge of the gable roof.  The bob wall was 5 feet 6 inches thick at base, narrowing to 5 feet and to 4 feet 6 inches under the bob. The wall opposite the bob wall measured 3 feet thick at the base, narrowing to 2 feet 6 inches. The stack was square in section, four feet wide at the top, and extended just above the roofline.

The engine house accommodates an engine with a forty-eight inch bore of and a stroke of seven feet. The cylinder is bricked in.

The engine house and the stack are constructed from ashlar (dressed stone); the stack is square in section. The roof of the boiler house is not shown.