1 Up to 1853, all Ordnance Survey maps were engraved on copper; but, in 1854, lithography was adopted for the 0 and scales. This was soon displaced by zincography, which has in turn, since 1889, given place to photo-zincography. The art of printing a line-photograph in permanent ink from a zinc plate, or photo-zincography, was discovered in 1859, but excepting for the reproduction of national MS., no practical use was made of the discovery until 1881, when the process superseded engraving for the production of the 6-inch map. To obtain the full advantages of the process, the MS. 200 plans were drawn in a style suitable for reduction, i.e. the buildings were coloured yellow to reproduce black, and the names, ornament, numerals, etc., were exaggerated so that their reduction might be of the proper size. This arrangement had its disadvantages. The 2500, or parent map, still continued to be published by zincography, and was really sacrificed to its offspring, the 6-inch map, which was published months in advance of its parent. It also ruined the drawing, which was formerly so much admired, for the draughtsmen, realising that their efforts were only directed to the preparation of a groundwork for a mechanically-reduced map, lost interest in their work. In Ireland, however, where photo-zincography has never been introduced, the MS. plans continued to be very beautiful works of art. Photozincography has now been adopted for the publication of all new plans on the and scales, with the following advantages:-Fidelity of reproduction of the original; saving of cost in the case of close work; acceleration of publication; uniformity of execution; great improvement in the style of original drawing; and facility in revising town plans. The parent plan has also resumed its proper place in the publication in advance of the 6-inch map. The photo-zinco process is so well known that I need not describe it here, except to point out the large scale upon which photo-copying is being carried out by the Ordnance Survey Department. The oo plans are photographed their full size of 38:016 inches by 25.344 inches; and the glass plates measure 45′′ × 30′′, and weigh 33 lbs. The paper used for the photo-transfers is Evans' thin paper; and it might be thought that a system of photographic reproduction, based on a flimsy paper transfer, would introduce many elements of inaccuracy. In practice, however, the process is found to compare favourably, as regards accuracy, with zinc etching methods, and engraving on stone or copper. Impressions varying more than one-sixth per cent. from the true scale are now cancelled. This result is very largely due to the skill that has been acquired by the photographic and printing staff. 1 2500 1 500 The following method has recently been adopted for producing the 1 plans of large towns from the 500 plans:-A convenient number of plans are pinned together, and a negative of the reduction obtained in the usual way. From this negative a cyanotype print is obtained, the result being a pale blue image on a white ground. The necessary drawing is now proceeded with on the cyanotype, and, when complete, it is fixed in its proper position with the surrounding 200 detail, and then re-photographed for publication. The maps are now printed by a specially designed steam zinc-plate printing machine, which, when necessary, can print 900 impressions an hour. THE 6-INCH SCALE.-Until 1881, the 6-inch map was engraved on copper, the reduced detail being obtained from the 500 map by photography. In 1881 it was decided to abandon engraving in favour of photo-zincography, and the practice was to pin four sheets together with their proper margin, and reduce them at once to a quarter sheet. 1 2500 1 2500 The present system is to take a blue impression of each sheet as it is being printed for publication, and upon this to pen in to scale all detail that is to appear on the 6-inch map, in black, whilst the names, ornament, trees, numerals, etc., are typed in an exaggerated style, so as to be of suitable size when reduced. All parcel and area numbers and unimportant detail are not penned in, and, being in blue, do not photograph. Four such plans, forming a 6-inch quarter sheet, are placed together and reduced at once by photography. The parks, mud, and sand are inserted in a tint by transfer from copper after the phototransfer has been laid down on zinc. The 6-inch quarter sheet was adopted partly for convenience, the size being much more handy than that of the full-sheet, and partly for acceleration of publication, for a quarter sheet can be published as soon as the four component 500 plans are received, without waiting for the other twelve. 1 It may be mentioned that, as an experiment, sixteen plans were placed in position on a screen with the proper margins, and a full 6-inch sheet produced from them in one operation. There was a slight distortion towards the corners, but I believe this may eventually be overcome. THE 1-INCH MAP.-The MS. map on the scale of 1 inch to a mile is produced from the 6-inch maps by the aid of photography. The 6-inch map is printed in light-blue ink, and the detail that is to appear on the 1-inch map is then penned in with black ink. By this means only the details in black appear on the reduced photograph which is used by the engraver. This reduction also gives the index map to the sheets in a 6-inch sheet, which, by the use of stencil plates, we are able to sell coloured for 2d. One of the most troublesome details we have to deal with in producing the 1-inch map is the selection of the names and artificial features that are to appear on the smaller scale. In the old 1-inch map this difficulty did not occur, for the survey was made on the 1-inch or 2-inch scale, and the surveyors only showed those features that could properly be represented on that scale. The old 1-inch was also a military map, and details not of military importance were omitted. The new 1-inch map is produced by a more or less mechanical reduction from the 25-inch plans, by men who have no personal knowledge of the details on the ground. This led at first to the occasional omission of detail, such as clumps of trees, which though very prominent on the ground did not appear to be so on the large-scale map. To meet this difficulty, prints from the reduced photographs are now examined on the ground by highly trained men, who eliminate unimportant detail, and add important features that have accidentally been omitted during the process of reduction. The prints are also examined, in a more general manner, on the ground, by an officer, and the names that are to appear on the 1-inch map are also checked by an officer. In this manner we try to ensure accuracy, and avoid overcrowding of detail and names; and I think the sheets that have been published during the last year will bear comparison with the maps of any country. It must be remembered in comparing the English 1-inch map with the maps of other countries, that whilst the latter, on scales analogous to the one inch, are military maps, the military character of the 1-inch map has had to give way to the civil requirements of the State. There is, too, no country in the world which is so covered with artificial features, houses, roads, railroads, etc., as England; and the representation of even a selection of these must overcrowd a map on a small scale. There are, it may be remarked, quite as many complaints of omissions as of overcrowding, and features which some people consider to largely enhance the value of the map are denounced by others as useless and disfiguring. The old system of engraving the 1-inch map was in the first place to engrave all the outline and writing upon a plate of mercantile copper. A matrix was then taken by the electrotype process, and from this a duplicate copper-plate was made, upon which the contours were engraved. This plate was used for printing the copies sold in outline, without the hill features. The hill features were afterwards added to the original plate. This system had one great disadvantage, that whenever a new railroad or road was inserted on the plate, the hills were damaged, and had to be repaired at great cost, but it had the advantage of requir ing only a single printing. The introduction of the steam copperplate press has enabled us to bring the present system into use. All the outline, including the contours, is now engraved on one plate, and the hills on another; and the hill impressions are produced by double printing. The hill plate will now never require repairing, and will always preserve the character given to it by the original engraver. It is also possible to print the hills in any colour. The electrotype process is used to produce duplicates or facsimiles of the engraved plates, which show signs of wearing after 700 or 800 impressions have been printed. The electric current was formerly obtained from voltaic cells of Smee's pattern; but these have been replaced by a dynamo driven direct by a Willans high-speed engine. The system of steeling the surface of the plates is also now used. Line engraving is a very slow process, and it is difficult to find engravers with sufficient skill and artistic taste to engrave the hill features on the 1-inch map. We have, therefore, for the last two years, been trying to discover some more rapid process, and one that should combine on the same map the mathematical accuracy of the contours, with the pictorial effect of hill-shading. We have, unfortunately, only been successful to a certain extent, but the difficulty seems to have been overcome by a German publisher, Herr Petters, who has produced a very good result from one of the brush-drawings of the 1-inch map. The processes of the survey were described in great detail, in a series of papers communicated to Engineering in 1888 by Captain Sankey, to which I would refer those who are interested in them. A very good general account, of which I have largely availed myself, is contained in a lecture given by Major Washington, R.E., at the School of Military Engineering, Chatham. There are some points connected with the survey to which I should wish to draw attention. The revision of the Survey has unfortunately fallen very much in arrear; so much so, in fact, that in many places revision means a re-survey. The necessity for a revision has frequently been pointed out by the officers who have had charge of the Survey; but it was not authorised until December 1886. The question of revision is purely one of money. It is, I think, hardly possible for the Survey Department, with its present staff, to overtake the heavy arrears, and get the map of the country into a normal state; but those arrears once cleared off, it would be a simple matter to revise the country once every fifteen years, and town districts oftener. In view of a periodical revision, I have roughly divided the kingdom into revision districts, and as opportunity offers I am moving the division officers into centres, which will probably be permanent. Thus, the division officer at Edinburgh will, as the revision of Scotland progresses, be responsible that the revised plans are afterwards kept fairly up to date. I propose to invite the surveyors of the large towns to place themselves in communication with the division officer, and to inform him annually of extensive improvements or additions. These would be surveyed every two or three years, and transferred to the large negatives which are kept at Southampton. In this manner the plans of the large towns will be kept well up to date. The plan that I am adopting will allow no new work to fall into arrear; the time when old arrears will be cleared off depends entirely on the annual grant to the Survey. In the utilisation of the Ordnance Survey maps the Irish Government is quite twenty-five if not fifty years in advance of Great Britain. In Ireland townland boundaries and areas, as ascertained and shown upon the Ordnance Survey maps, are the legal boundaries and areas of the townlands, and they can only be altered with the sanction of the Lord Lieutenant and Privy Council of Ireland. As there are rather more than 62,000 townlands in Ireland, averaging a little over 300 acres each, it will be seen that that country contains a large number of small, practicable, and well-defined units, from which all other divisions, such as parishes, baronies, counties, unions, and electoral divisions can be built up. Disputes as to townland boundaries are unknown. It may be added that no private boundaries are shown on the plans; the Ordnance Survey only deals with administrative boundaries. The Irish Valuation Acts provide that the Ordnance Survey maps are to be used in ascertaining the areas of tenements, and a very good system of valuation is in force. The cost of the original tenement valuation was 3 d. per acre, or £10 a square mile, and this included the marking of the tenement boundaries on the Ordnance maps; the computation of the areas; the valuation of the land, buildings and all other property; the settlement of appeals; and the issue of final lists for rating purposes. The time occupied in each county from the commencement of the valuation to the issue of the valuation list was about two years. In Ireland, too, the maps are used in all transactions affecting land under the various Land Acts; and it may be said that, as the great "Down" survey was made the instrument for conveying to the adventurers and soldiers of Cromwell's army lands taken from the old Celtic owners, so the Ordnance Survey has become the instrument for conveying the same lands to the tenant descendants of those owners who have been enabled to purchase their holdings by recent Land Acts. In Great Britain the case is very different. The boundaries and areas on the Ordnance Survey maps are not legal, and the maps are very rarely used for local assessment or administrative purposes. The nation deliberately undertook this elaborate Survey, on the ground that no private enterprise could accomplish it satisfactorily; and now, after spending millions on its production, the country hesitates to make use of the maps in the manner intended by the able statesmen and scientific men upon whose recommendation it was authorised by the Government of the day. It is hardly necessary to refer to the errors, irregularities, and inconsistencies of the valuation for local assessment in this country, and to the erroneous areas in the rate-books. The areas of some parishes in the Poor Law Return of 1882 are as much as from 400 to 1600 acres less than the true areas ascertained by the Survey. In one parish an owner is rated for 40 acres more than he possesses, and another owner for 84 acres less. The valuation list, directed by Section XIV. of 25 and 26 Vict. cap. 103, to be made by overseers of parishes, does not refer to the Ordnance Survey or its maps; and it may be said that, as a rule, the guardians, overseers, and rate collectors act as if there were no such maps in existence as those of the Survey. The Ordnance Survey maps on smaller scales might also be used advantageously as the basis for the preparation of statistical maps. The price at which the Ordnance Survey maps are sold has been much criticised, and has been compared unfavourably with the prices of foreign maps. This question is a somewhat complicated one; and it is not easy to institute a fair comparison between the selling prices of English and foreign maps. For instance, in England the map-agent receives 33 per cent. for handing the maps over the counter; that is, for every 1-inch impression sold, the agent receives fourpence of the shilling paid by the public; for every three-shilling 25-inch map he receives one shilling. He receives also 333 per cent. on the cost of colouring. Thus, if a town plan costs ten shillings to colour, five shillings has to be added to this for the agent. This, in itself, is a heavy tax on the English maps; and, it may be added, that the paper on which the English maps are printed is much superior to that used abroad. As |