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Bob
Robert Bradley
Retired Surveyor


Surveyor - Page 3


A Surveyor’s Job
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The Surveyor’s Job At A Coal Mine


In 1860, further legislation in the form of the Mines Inspections and Regulations Act required the owner of the mine, as well as keeping an up to date plan, to give written notice of abandonment, discontinuance or the commencing or recommencing of underground workings in the mine. However it was not until the Coal Mines Regulations Act of 1872 which required a proper official repository for the deposition of abandoned mine plans, that the workings of a mine shown on a plan, had to be deposited within 3 months of abandonment.A copy of the original plan on transparent linen could be made for the deposit.  No other person was allowed to see the abandonment plan until an interval of 10 years had elapsed. 

Unfortunately many copies of the workings were deposited with only the barest information shown, which was required by law. Usually the outline of the extent of the workings was delineated, a North point, and the position of the shafts and maybe the general direction of dip of the seam if known.The original plan that contained much more information could contain the roadway positions, depths of shafts, gradients, seam sections, possibly waterlogged areas, etc.The original plan of the workings would have been kept by the owner and sometimes put in a safety deposit, and over the years may have been lost or destroyed.

Scales

In the past many different and somewhat strange scales were used to construct the plans, such as 1 chain to 1 inch, 2 chains to 1 inch, 4 chains to 1 inch, 6 chains, 9 chains etc, with measurements in links, later feet and inches and yards.  Also plans to the scale 6 inches to a mile were constructed.  The scale 2 chains to an inch or 1:1584 was a popular one, and later 1:2500, which was the scale chosen by the Ordnance Survey for the future.  The workings were plotted on these plans by protractor and later various grids were used. Some were local grids for that colliery only. Others were grid values used at all the collieries owned by that Colliery Co.
Measurements today are done in metres.  Generally the plans were oriented to the magnetic North. The Act of 1872 also required that Managers of mines be qualified, and examinations for First Class Certificates of Competency were introduced, from 1873. Managers in post were given service certificates.

The 1887 Act also required that Undermanagers be qualified, and examinations for Second Class Certificates were introduced. Again practising Undermanagers were awarded service certificates. The Act also required that both Managers and Undermanagers should have at least 5 years practical experience in mines.  A further requirement was that in future the mine plan was to be updated at quarterly intervals instead of the existing six monthly time period.

The later Coal Mines Regulations Act of 1896 required greater detail to be shown on the working plan of the mine and to be produced by a ‘competent’ Surveyor.

The Coal Mines Act of 1911 required that in future, plans to a scale of not less than 2 chains to an inch (1:1584), were to be prepared by or under the supervision of a ‘qualified’ Surveyor. Examinations were introduced. Service certificates were granted to practising surveyors. Subsequently, a statutory period of practical experience and the passing of both written and practical examinations, including an oral test were set by the Mines Qualifications Board.

Prior to the turn of the century, mine owners employed a Manager to run the pit and he or his sons or relatives used the dial as part of their duties to gain experience, to survey the mine workings, as part of the examination for a Certificate of Competency is a basic knowledge of surveying.  Some owners employed Viewers or Surveyors who went round the area overseeing the working and took sections and measurements and dial readings to produce plans.

Many of these small mines were amalgamated and grew into larger concerns and therefore required more accurate plans and surveys, as many of the mines were coupled up to one another to increase efficiency.

The Act of 1930 actually created amalgamations, and huge companies were formed, e.g. Powell Duffryn in South Wales, being the largest with some 60 odd pits eventually.  Local companies were the Butterley Company with up to 13 pits, the Stanton Ironworks Company with about 6, the Clay Cross Company similarly, the Blackwell Colliery Company, the Bolsover Company, Staveley Coal & Iron Co, New Hucknall Colliery Co and Sheepbridge Co etc also with about 6 pits.  Plans and surveys would generally be similar for a particular company, the Chief Surveyor being responsible.

Statutory standards for mine plans and surveys were set in 1935. A joint report by the Institute of Mine Surveyors and the Royal Institution of Chartered Surveyors was published entitled ‘Standards of Accuracy and Limits of Error for Plans and Surveys of Mines’. One of the main recommendations was that all plans be orientated with, and correlated to, the Ordnance Survey National Grid, as many plans were plotted on local grids or orientated to surface features, and many neighbouring mines were not even on the same system, particularly if they were in competition. Examples were Line of pits grid at the three local Stanton pits; Dunnose grid for some Butterley pits; Hewitt’s grid and Local grids for others, etc. and so on. Some pits had grids in feet denominations, others in links. Danger lurked! The Ordnance Survey National Grid covers the whole of the Britain with the zero start point for Eastings and Northings being an imaginary point off the coast of the Scilly Isles. This position was chosen so that all the grid values would be positive.

From this report also, regulations were introduced and examination candidates for the Surveyors’ certificate had to produce evidence of having reached a prescribed standard in their general education before being accepted. Candidates were also required to provide evidence that they had carried out surveys, levelling, measuring etc underground for a period of 2,000 hours minimum.

Some of the larger companies actually coupled mines together, but the period of the Second World War in the 1940s saw mines coupled up for emergency escape routes in case of bombing under the ARP rules. Surveys were made between the respective connections particularly at the Bolsover pits and comparisons obtained for the respective pits’ bases. Other collieries were connected to one another for efficiency measures or as secondary egress should one of the two shafts at that mine was out of action. Errors were found at the extremities, some small and within the limits laid down. Others were found which required adjustments in bearings and distance to be made. When headings from Thoresby coupled through to the old Ollerton workings some years after Ollerton had closed in 1994 I was extremely pleased to learn that when theodolite surveys from Thoresby were coupled to old bases left by me at Ollerton the value obtained was only a few seconds of arc.

Also the datum in use for the underground levels varied widely. Some pits worked to Ordnance datum or sea level, others to 1,000 feet below sea level, 2,000 feet, 3,000 feet etc. The whole system was fraught with danger. Limits of error and standards of accuracy were specified but even after Nationalisation on 1 January 1947, there were still many anomalies, until 1951-1952, when a standard Code of Surveying Practice was issued by the National Coal Board. This code laid down very stringent rules and accuracies for surveys, and e.g. the maximum error allowed for correlations of the surface and underground workings was 2 minutes of arc. Also in future all plans were to be prepared and plotted on the 1:2500 scale on 2 kilometre by 1 kilometre sectional sheets corresponding to the Ordnance Survey plans. All levels would have a datum of 10,000 feet below Ordnance Datum or sea-level. This was chosen so that all levels would give a positive reading, and a simple subtraction between two levels whether they be both underground, or one underground and the other on the surface, would give the difference between the two in feet. For example a level on the surface at 550 feet would be shown as 10550. A level underground could be 9860 feet. The difference in level between the two specified readings would be, 10550 – 9860 = 690 feet.

In future all writing on the plans was to be standard and done using special pens with black or coloured inks and various sized stencils. The plans of the past were always written on and dated etc in free hand writing, the style depending very much of course upon the individual. It was generally noticeable where one person had taken over from another in updating the mine plan, as the style of the writing would change. In future all sectional plans would have a very similar look, the only things being different would be the co-ordinate values of the grid, the colliery name, the seam name, and the different shape of the workings on the sheet. All the workings would be drawn in red carmine ink and stippled with red flecks. All seams would have a separate plan for each, and any workings of any other seam within 40 yards or 37 metres above or below the seam depicted would be shown in a different colour in outline only, unless an overlay tracing was kept, with the permission of the Inspector, when the other seam workings need not be shown. In this case the overlay or overlays would be kept with the working plan. The new plans were to be kept in special envelopes with plastic transparent fronts to allow the plan to be kept clean and to be seen without removing it from its envelope. The new plans were constructed as in the past, on brown ‘Holland’, a stiff white cartridge paper with a brown linen backing. However the plans of the past were usually large, to accommodate the whole ‘take’, and in being so large, were rolled up. Continual rolling and unrolling usually took its toll, with the paper cracking and flaking, ultimately with the loss of accuracy and maybe some detail of the plan. Sometimes thin wooden slats were fastened to the ends of the plan to assist with the rolling up and as an added protection. In addition quite a few lead weights, usually covered with leather and seam stitched were necessary to hold the plan reasonably flat when unrolled. When a new plan required making, it was a colossal task, as everything from the surface features, including copyhold areas etc, and the mine workings of the past were delineated on it. This lead to much of the old work being left off, when a new plan was made in order to save time. Unfortunately this also lead to other bits of valuable information being left off as well, such as levels, gradients, faults with throw, old staple pits, boreholes etc. These old plans were very cumbersome and large drawing tables were necessary to allow work to be carried out on them. The old plans would generally have different coloured inks to depict each quarter of a year’s work and would also have the area worked coloured. Also designated would be the surface boundaries of freehold or copyhold areas, both using a watery colour wash, which again did not help for accuracy, as the paper and linen would tend to stretch, buckle or shrink depending upon the material. ‘Rubbed up’ stick ink is still used.

The new plans could easily be stored flat in drawers or hung in special folders, firstly in wooden cabinets and later steel fireproof cabinets, which also kept them safer and cleaner. Generally, both the old and new plans were kept in a plan safe fitted with a large steel fireproof door, similar to a bank safe.     

Of course the making of the ‘new’ plans was very laborious indeed also, and handmade as previously, and most of the information had to be extracted from the old plans, usually on a different scale, by a variety of methods. Photography with reduction was supplemented by the re-plotting and in many cases the re-calculating of old survey notes, to give base lines to work to. Other methods were resorted to as well, such as eidographs, pantographs, re-plotting by use of squares or rays, tracing old works on the same scale and pressing through using red carbon paper, etc. All these methods also required the information to be inked in afterwards, a long and laborious task. Nowadays all plans barring the working plan are constructed on a computer and coloured prints achieved by means of large printers.

Some of the earlier work done after Nationalisation unfortunately had to be re-done later, when it was deemed that all new plans were to be constructed on aluminium backed white cartridge paper, as some of the earlier plans on ‘Brown Holland’ had either shrunk or stretched, as had their predecessors. The new material was quite a stable one and the grids, which were pricked through using a special tool which fitted in a very stable metal template made from invar, and once inked in using drawing pens, kept their true size and shape. Prior to this, grids were constructed by hand methods that again took time.

An early stiff plastic material used to create overlay tracings was found to turn brittle and shatter under certain conditions and ageing. Another better more pliable plastic material was found which has survived to the present day in perfect condition. Again unfortunately this led to the plans having to be re-made, although certain plans in parts of the country were photographed and copies produced.

The Code of Practice (in 2 volumes) also outlined the form of all other plans to be kept at a mine and examples of each were portrayed along with sizes of stencils to be used for the writing. Standards of accuracy for all types of surveys and levellings were laid down also.

A further updated version of the Code of Surveying Practice was issued, following the tip disaster of Aberfan in 1966 and other serious underground incidents. The difference in bearing for correlation of surface and underground was now limited to one minute of arc, instead of two, increasing the standards by double. One major feature in this edition was the proposed metrication of all mine plans. This was another colossal task. Although the grids of the plans were already metric, and the mine workings were plotted in metric, the seam sections were in inches, the faults were shown in feet and the levels and contours and level values were in blue to a datum 10,000 feet below Ordnance Datum (sea level). Because the mine workings were drawn on paper and stippled in red, it was very difficult, if practically almost impossible, to erase every figure which was in imperial measurement and change it to the corresponding metric equivalent, without creating a bad ‘mess’. It was impossible to just change the contour value to metric, because the old imperial values were in 50 feet intervals and the new metric values in violet colour were to be in 5 or 10 metre intervals, which of course did not correspond to the same contour positions. However the change back to sea-level as a zero datum, meant that once more there would be negative values for most underground workings and positive values for surface values, and great care would have to be taken to determine depths. A + sign was adopted for all values above sea-level. For example a working was at 555m below sea level and the surface level at the top of the shaft was +45m. By calculation.....minus 555 plus 45m = 600m deep below the surface.

It meant once again that all new sectional mine plans, and overlay tracings where used, had to be re-made. Fortunately a transitional time period was allowed before completion was required, the larger mines suffered, as generally there were more sections to construct in the time allotted. For example at Ollerton there was 29 flat sheets for the Top Hard seam that was first worked in 1925 and abandoned in December 1978.

Although the carrying out of the statutory and many other subsidiary surveys, thirling surveys, correlations and levellings, and the preparation of the mine plans and the many other plans required are always the principal task of the mining Surveyor, there are many other tasks, duties and responsibilities which are allied to the work of the Surveyor.

Prior to Nationalisation in 1947, additional duties usually carried out by the Surveyor were mine planning, geological reports, supervising drilling both surface and underground, ventilation surveys and air measurements, analysing coal, dust sampling, subsidence claims, designing colliery buildings and houses, laying out sports grounds, divining, colliery rating, royalty returns, printing colliery notices, report writing and many other jobs which may have been peculiar to a particular company, unable or unwilling to be taken on by other management staff. Remembering of course that the management team at a mine was usually the Manager, Undermanager, Engine Wright, Head Electrician, the Surveyor and a Chief Clerk. Not many that one could pass jobs on to! Some of these jobs lingered on albeit that other departments had been set up.

In the early days of reproduction of notices or plans, the sun was used as a source of power by placing a negative over special paper in a frame and hung out of the window by ropes facing South and relied on the sunshine burning away the part that was not required and then using a developer would ‘wash’ the paper with the solution to give the desired result. Of course if the sun did not shine or it was cloudy there were problems! Printing machines using carbon arc lamps were introduced by some companies, mainly in the 1930s. It was in the late 1950s that more modern printers were designed, these too being superceded in later years with speedier machines saving many hours of time. However most of these machines used weak ammonia-based solution as a developer, the smell being quite strong and could lead to watering of the eyes. In later years extraction fans were installed in the printing rooms or were an integral part of the modern machines to get rid of the smell and to comply with new legislation. Other ‘dry’ type printing/developing machines were introduced at some mines.