REPORT ON THE Jtpjitotiotts of fftoto0ti»^| AS USED IN THE TOPOGRAPHICAL DEPARTMENTS OF THE PRINCIPAL STATES IN CENTRAL EUROPE, WITH NOTES ON TITE EUROPEAN AND INDIAN SURVEYS. BY LIEUT. J. WATERHOUSE, R. A., ASSISTANT SURVEYOR GENERAL, IN CHARGE OR THE PHOTOZINCOGRAPHY BRANCH OP THE flURTEXOE GENERAL’S OPPICE, CALCUTTA. CALCUTTA: OFFICE OF SUPERINTENDENT OF GOVERNMENT PRINTING. 1870 . REPOET ON THE CARTOGRAPHIC APPLICATIONS OF PHOTOGRAPHY AS USED IN THE TOPOGRAPHICAL DEPARTMENTS OF THE PRINCIPAL STATES IN CENTRAL EUROPE, WITH NOTES ON THE EUROPEAN AND INDIAN SURVEYS. BY LIEUT. J. WATERHOUSE, R, A., ASSISTANT SURVEYOR GENERAL, IN CHARGE OE THE PHOTOZINCOGRAPHIC BRANCH OF THE SURVEYOR GENERAL’S OFFICE, CALCUTTA. CALCUTTA: OFFICE OF SUPERINTENDENT OF GOVERNMENT PRINTING. 1870 . Digitized by the Internet Archive in 2017 with funding from Getty Research Institute https ://arch i ve. o rg/d etai Is/reporto n cartog raOO wate TABLE OF CONTENTS CHAPTER L FRANCE. PARIS. PAGE. I.—Topographical Department of the Ministry of War 1 II.—Application of Photography to Military Surveying ... 11 III. —Imperial Printing Office ... ... ... ... 18 IV. —Photolithography ... ... ... ... ... 25 V.—Photographic Engraving ... ... ... ... 26 VI.—Lithographic Establishments ... ... ... ... 29 VII.—Bank of France ... ... ... ... ... 33 DORNACH. VIII.—Braun's Carbon Printing Establishment ... ... ... 34 METZ. IX.—Phototype Process of Tessier du Mothay and Marechal ... 36 CHAPTER II. BELGIUM. BRUSSELS. I.—Topographical Department ... ... .. ... 33 II.— Toqvey's Process of Photolithography ... ... ... 51 III.— Van der Maelen’s Geographical Establishment ... ... 52 CHAPTER III. HOLLAND. THE HAGUE. I.—Topographical Branch of the War Department ... ... 54 AMSTERDAM. II.— Visit to Mr. Asser ... ... ... ... ... 55 IV CHAPTER IV. GERMANY. GOTHA. I.—Justus Perthes’ Geographical Institution leipsic. 1.—Payne’s Printing Office II.— Brockhaus’ Printing Office CHAPTER Y. PRUSSIA. BERLIN. I.—Topographical Depot of the General Staff II. —Royal State Printing Office III.— Photolithography CHAPTER YI. SAXONY. DRESDEN. I.—Topographical Bureau CHAPTER VII. AUSTRIA. VIENNA. I.—Military Geographical Institution II.—Imperial Printing Office III. —Photographic Establishment of the Artillery Committee IV. —Photolithography CHAPTER VIII. BAVARIA. MUNICH. PAGE. 67 70 72 73 75 83 87 88 97 100 101 I.—Topographical Bureau II.—Herr Albert’s Photographic Establishment 102 108 V CHAPTER IX. SWITZERLAND. BERNE. PAGE. I.—Topographical Department of the Federal Staff ... ... 109 NEUCHATEL. II.—Observatory ... ... ... ... ... Ill CHAPTER X. General Resume ... ... ... ... ... 117 CHAPTER XI. INDIA. SURVEY DEPARTMENT. Great Trigonometrical Survey ... ' ... ... ... 123 Topographical Surveys ... ... ... ... ... 126 Revenue Surveys ... ... ... ... ... 128 Surveys in the Madras and Bombay Presidencies ... ... 131 Surveyor General’s Office, Calcutta ... ... ... 131 Mathematical Instrument Department ... ... ... 151 APPENDIX A. Extract from Marshal Vaillant’s Report on M. George’s method of CORRECTING ENGRAVED COPPER PLATES ... ... ... 152 APPENDIX B. Extract from “ a Memorandum on the application of Photography to Surveying” by M. Laussedat ... ... ... ... 155 APPENDIX C. Orders for the conduct of the Belgian Survey ... ... 167 APPENDIX D. Specimens of the Field-books and other forms used in the Belgian Survey ... ... ... ... ... 177 APPENDIX E. On the application of Photography to Architectural and Land Surveying by A. Meydenbauer ... ... ... ... 188 VI APPENDIX F. INSTRUCTIONS FOR THE COMMANDING OFFICERS OF THE PRUSSIAN TOPOGRAPHICAL. J3URVEY. A. —General order relating to management and economy. CHAPTER I. DURING THE SURVEYING SEASON. § 55 55 1 . 2 . 3. 4 5. 6 . General regulations and duties Communication with, and conduct towards, civil authorities Quarters Dress of Officers Monthly Reports Settlement of Accounts PAGE. 201 203 203 203 203 205 CHAPTER II. RELATING TO THE TIME OF RESIDENCE AT BERLIN. § 7. Officers, when to report themselves ... ... ... 208 „ 8 . Office hours and occupation ... ... ... 208 „ 9. Officers’ servants ... ... ... ... ... 209 „ 10, Surveying pay and service pay ... ... ... 209 „ 11. Furlough ... ... ... ... ... 209 „ 12. Working-hours in the Topographical Department ... 209 B.—Regulations regarding Surveying. CHAPTER I. GENERAL OBSERVATIONS. § 13. Requirements from Officers ordered on surveying duty ... 210 „ 14 General arrangement of the surveys ... ... ... 210 „ 15. Instruments and materials ... ... ... ...211 „ 16. Measuring distances with the kippregel and surveying staff 213 „ 17. Reading off angles on the vernier, and application of the angle of correction ... ... ... ... 213 „ 18. Testing of instruments ... ... ... ... 214 „ 19. Manuals or treatises on surveying ... ... ... 216 CHAPTER II. ON THE PROSECUTION OF THE SURVEY. § 20. Reconnoitering the section and testing the trigonometrical 217 POINTS vn § 21. Fixing stations by intersections „ 22. Testing stations by backward intersections „ 23. Determination oe heights „ 24. Fixing oe staee stations „ 25. Terminating work at a station „ 26. Continuing work at a new station „ 27. Penning in and drawing oe field work „ 28. Use oe private plans „ 29. Assimilation oe the margins oe plans „ 30. Boundaries „ 31. Survey oe eortieications „ 32. Completing the survey „ 33. Privacy oe surveying documents CHAPTER III. DRAWING OF PLANS, § 34. General remarks „ 35, Penning in contour and intermediate lines „ 36. Terraces and ravines „ 37. Turnpike and other roads „ 38. Buildings „ 39. Trigonometrical and geometrical points „ 40. Elevations „ 41. Writing on plans C. —General observations regarding details of the survey. § 42. Military ground-plans ... ** 43. Statistical notices ... ... 99 44. Nomenclature • •• 99 45. Divisions oe land ... t • • 99 46. Concluding report 99 47. Reconnoitering roads and rivers 99 48. General descriptive report on the COUNTRY llt D.~Supplement. PAGE 219 219 221 223 224 224 224 225 225 226 226 226 227 227 228 228 228 230 230 230 230 232 233 233 233 233 233 235 § 1. Regarding the amount of work expected from the topographer 237 „ 2. Order regarding the nomenclature ... ... 238 INDEX Anastatic Printing -Process, Appel’s . . . -—Military Geographical Institution, Vienna . Application of Photography to Surveying ——-—Clievallier’s system . --—Laussedat’s system .... --—Meydenbauer’s system . . . Asser, Mr., visit to. 120 148 96 11, 75, 122, 155, 188 11 . 16, 155 . 75, 188 66 Bank of France.. 33 Barometrical registers.. . 115 Braun’s Carbon Printing Establishment, Dornach ....... 34 Carbon Printing . 34 Chemical Engraving, Vial’s Process ......... 31 Chemitypy . • ... . . 67, 71 Chromo-litho Engraving.61 Chronometers, rating of, at Neuchatel Observatory.114 Chronograph. .113 Chronoscope. . 114 Copper-plate Printing ............ 7, 98 Correcting Engraved Copper Plates ..2, 91, 119, 152 --Zinc Plates.147 Electrotyping. Enfacing Engraved Copper Plates with Steel . Engraved Copper Plates, Correction of . -M. George’s system -Vienna system ..... Engraving Blocks for diagrams --^Chemical, Vial’s Process of — -on Copper . . . . . — -on Stone ..... --Photographic . ——--Prussian Bank notes . 6, 24, 69, 71, 78, 92, 99, 119 7, 28, 71, 119 104, 119 .2, 152 .91 .19 .31 2, 24, 67, 75, 87, 91, 104, 110, 118, 133 24, 30, 47, 59, 61, 67, 75, 104, 119 26, 79, 85,121 .76 Geographical Institutions— -Justus Perthes’, Gotha.. . » 67 -Military Geographical Institution at Vienna . . .. . gg -Van der Maelen’s, Brussels . . . ..52 Gibbet-Press ....... 77 241 INDEX. Kippregel . 74, 213 Levelling Compass . . — -—Instrument, Colonel Weiss’ — ---—Swiss « , Lithographic Establishments— -—-—Bavarian Topographical Bureau „ ———Belgian Topographical Depot -—Dutch Topographical Bureau —-Engelmann’s, Paris .... --Erhard’s, Paris . » - Imperial Printing Office, Paris ---- .. . - - ■ -Vienna » -—Lemercier’s ——Military Geographical Institution, Vienna -——Royal State Printing Office, Berlin --Surveyor General’s Office, Calcutta Lithographic Presses— --Austrian ---Bavarian --Dutch ^— —French ■——German of Austrian Empire -—Bavaria —Belgium . —England , —France —-Holland . -India —Prussia —-Saxony -Switzerland Maps, preparation of, for Photozincography Mathematical Instrument Department, Calcutta Observatory at Neuchatel, Switzerland . Photographic Apparatus . Photographic Engraving Processes— — -Baldus’ - —Drivet’s ———Durand’s --Falk’s — -Garnier’s - ■ - -Niepce de St -Placet’s Victor’s 49 102 116 105 47 66 30 30 21 98 29 93 77 135 93 105 47 21 71, 77 88, 118 107, 118 38, 118 118 1, 118 54, 118 132, 118 73, 118 87, 118 109, 118 137 151 111 10, 40, 65, 78, 83, 84, 93, 99, 105, 138 102 , 28 29 27 85 27 26 28 242 INDEX. Photographic Engraving Processes— -—Royal Printing Office, Berlin Photographic Establishments— -Artillery Committee, Vienna -Dep6t d’Artillerie, Paris . •--Herr Albert’s, Munich -School of Application of Artillery and Engineering -Surveyor General’s Office, Calcutta —-—Plane Table .... -Processes for Negatives --Printing Positives Photography. Photo-lithographic Processes— ———Bavarian Topographical Bureau -Belgium Topographical Depot ——Burchard Brothers’, Berlin . -Dutch Topographical Bureau -Kellner and Geiseman’s --Korn’s . ——Lemercier’s . --Leth’s . . — -Marie’s. •-Military Geographical Institution, ■-Reiffenstein and Roesch — -Toovey’s . . Phototype Process . Photozincography . Printing Bank notes Printing Offices— . -Brockhaus’ Leipsic -Imperial, Paris -- - Vienna . -Payne’s, Leipsic -Royal State, Berlin Printing on Tin Plates ■-Zinc Plates in relief Registering Machine, Gosset’s . Revenue Surveys in India Ruling Machines Silver Printing , , . -on Stone . —- - —-Rapid by development Stadia. Stereotyping .... Survey, Belgian, Instructions for -Prussian, Instructions for Vien Metz 39, 11 5, 79, 94, 33, 35, 45 33 79 100 25 108 25 135 11 105, 136 95, 106 120 106 43 83 64 85 83 25 101 25 95 101 51 36,121 120, 136 76, 98 72 18 97 70 75 107 23, 119 21 128 63 11, 35, 45, 95, 106, 108, 140 61 11, 45, 106, 141 . 48, 103, 116 . . 19, 70 . . 167 . . 201 U3 INDEX. Surveying Instruments Surveyor General’s Office, Calcutta Surveys .... --Austria --Bavaria — -Belgium ———Holland -—-Prussia -Saxony — -Switzerland . Surveys in India— --Great Trigonometrical . -Topographical --Revenue ———Madras and Bombay . 13, 48, 74, 90, 102, 116, 117, 124, 126, 128 131 117 90 74, 102 47, 167 55 201, 210 87 110 123 126 128 131 Tin Plates, Printing on . Tessier du Mothay’s Phototype Process Topographical Departments— --—Brussels .... “——Berlin .... --Berne ... —Dresden .... ■ -India .... ■ -Munich .... -Paris .... --The Hague .... -Vienna .... Topographical Survey, India Transfer Ink ..... Trigonometrical Survey, India 107 36 85, 0, 9 96, 38 73 109 87 123 102 1 54 88 126 106, 143 123 Zincograpliic Printing Zinc Plates in relief . 77, 145 22, 83, 86, 100, 119 244 INTRODUCTION. Being compelled to take sick leave to Europe in March 1867 shortly after my appointment to the superintendence of the photozincographic operations in the Surveyor General’s Office at Calcutta, I determined to avail myself of the oppor- tunity of improving my knowledge of photozincography by going through a practical course at the Ordnance Survey Office, Southampton, the birth-place of the art, and also to acquaint myself with the kindred processes of photolitho¬ graphy and carbon-printing by Swan’s and Woodbury’s systems, and ascertain whether they might be advantageously employed for the reproduction of the maps of the survey of India. The Surveyor General of India, Colonel Thuiliier, It. A. s who takes great interest in the subject, was kind enough to forward my application to this effect with a strong recommen¬ dation, which was approved and forwarded to the Secretary of State by the Indian Government, and shortly after my ar¬ rival in England, I received an authorisation to visit the Ordnance Survey Office at Southampton. I proceeded to Southampton in June and remained there for about two months. Through the courtesy and kind assist¬ ance of Sir Henry James and his officers, I was able to make myself thoroughly acquainted with all branches of the work carried on there, but more particularly with the photo¬ zincographic process, which I worked out practically in every detail from preparing the rough zinc plates to printing off the copies. In September I paid a visit to the Paris Exhibition and took the opportunity of examining the photographs from various countries, and more particularly the results of the photolitho¬ graphic and photo-engraving processes used on the Continent, and found that specimens of these processes from France, X Belgium and Germany were superior to anything I had hither¬ to seen in England. I was unable at that time to make enquiries into the details of the processes by which such fine results had been obtained, but resolved that if a future opportunity should offer I would spend some months in visit¬ ing the best photolithographers and photo-engravers in Cen¬ tral Europe, and in ascertaining to what extent these pro¬ cesses had been applied to the reproduction of topographical and other maps, as I had been much struck with some speci¬ mens of the chromo-photolithographed map of Belgium. On my return to England I visited the Government Photographic Establishments at Woolwich, Chatham and South Kensington, as well as the carbon-printing establish¬ ment of Messrs. Mawson and Swan at Newcastle, Messrs. Nelson’s Printing Office and Messrs. Keith Johnston’s Geo¬ graphical Establishment at Edinburgh. In the spring of 1868 , I applied to the Secretary of State for India for such credentials as would enable me to visit the Topographical Departments of the principal Continental Governments and any kindred institutions I might be able to visit, with a view to studying the photographic and other pro¬ cesses in use for the production of maps of all kinds and obtaining any information I could, regarding the modes of survey adopted. My application was very liberally granted and in April I started on my mission, staying some weeks in Paris and thence proceeding to Brussels, the Hague, Gotha, Leipsic, Berlin, Dresden, Vienna, Munich, Neuchatel, Geneva, Berne, Dornach and Metz, visiting in each town the principal geo¬ graphical and topographical establishments, large printing offices, and any photolithographers or photo-engravers of whom I could obtain intelligence, as well as any arsenals and military manufacturing establishments that came in my way and were accessible, and returned to London in August after an absence of four months. xi I made as extensive notes as possible on each of the institutions I visited, hut as they generally had to be made from memory or from rough jottings made on the spot, I have had some difficulty in making my descriptions as complete as I could have wished. In many cases, however, I have had the aid of manuscript or printed notes containing the information I required, and have given translations of such notes just as I received them, making occasional alterations in accordance with newer information. I have also availed myself to a small extent of other published sources, enabling me to give a fuller account of any processes of which I did not receive sufficiently full information. The diagrams with which the report is illustrated have, for the most part, been made from rough sketches taken on the spot or from memory ; they are merely intended to show the principles of the objects represented, and do not pretend to accuracy of detail or scale, but in some cases, which are duly noted, I have been able to copy from photographs or drawings. I was most courteously received by the authorities of all the Continental States I visited, and at most of the Govern¬ ment establishments information was very freely accorded and every assistance and facility given me for carrying out the object of my mission. A general desire was evinced by the chiefs of the different Topographical Departments to enter into relations with the Survey Department in India for the exchange of maps and information, and to have reliable maps of the country. I have also much pleasure in acknowledging the very kind and friendly reception I met with from all the officials and private individuals with whom the course of my enquiries brought me into contact, and I must express my sense of the liberality with which those professionally engaged in practising the arts connected with the subject of my studies, allowed me to see their establishments and furnished me with information on the processes they employed. The object I have had in view in the preparation of this report, has been to make it as complete and practically use¬ ful as possible, that it may not only afford practical informa¬ tion on the details of the photographic and photolithographic processes at present in use for the reproduction of maps and other works of art in line and half-tone, but at the same time give a general idea of the methods and processes employed for the execution of the topographical maps of the principal States in Central Europe, and of the instruments used for surveying, which differ considerably from those used in England and in this country. I have not described the processes used at Southampton for the production of the maps of the Ordnance Survey, because information regarding them is already available, and at the time of my visit I was told that a very complete description of the whole office and of the operations carried on in it was about to be published. I have also thought it unnecessary to describe the details of Swan’s or Woodbury’s process of carbon-printing, because full descriptions of them have already been published, and, moreover, although they are the most perfect processes known for reproduction in half-tone, I do not think they are capable in their present form of being advantageously applied to the reproduction of maps. In England the arts of photolithography or photozinco¬ graphy have not been applied to any extent to the reproduc¬ tion of maps, and although some exceedingly fine specimens have from time to time been executed at Southampton, the process is chiefly used for the reproduction of miscellaneous maps and of the national records, and not for the maps of the Ordnance Survey. In the Arsenal at Woolwich considerable use is made of photolithography for producing diagrams of military stores and equipments, but the process employed is almost identical with the Southampton process and therefore does not require description. Xlll This report was finally submitted to tlie Eight Hon’ble the Secretary of State for India in January 1869, shortly before my return to India, and was transmitted for disposal to the Indian Government who referred it to the Surveyor General of India with instructions to print the whole or Home Office memorandum No. 128, SUch P arts aS Seemed expedient, dated, Simla, 29th April 1869. Whilst going through the press, the text has been carefully revised and several portions which had no immediate reference to cartography have been omitted, and with the aid of a copy of the Memorial de rOfficier du Genie, No. 17, recently received from the French Government, more complete information on Laussedat’s system of the application of photography to surveying has been added. As a brief account of the methods adopted for the survey of a country of such immense extent as India, and of the scope and organization of the Indian Survey Department, as well as a description of the mode of working the photo- zincographic process in a tropical climate might prove inter¬ esting to many of those who have furnished me with similar information, I have with Colonel Thuillier’s permission obtained the information from the Surveyor General’s Office and added a chapter on this subject. In no country in the world has photography been so extensively and so usefully applied to the reproduction of maps as in India, where skilled lithographic draughtsmen and engravers are very scarce, all such agency having to be specially trained to the work from boyhood or brought out from Europe. By the aid of photozincography the maps of the various surveys can be issued to the public within a few months after the completion of the survey. In execution several of the photozincographed maps may be favorably compared with lithographed maps, and, as they are copied from the Surveyor’s originals, they are very accurate and are eagerly sought after by the local civil authorities and by officials connected with XIV the vast engineering operations now being carried on in all parts of the country. The utility of the process is being recognised more and more every day, and, although through the urgent representations of the Surveyor General, the Pho¬ tographic Office has recently been suitably accommodated and set up on a much more efficient footing than formerly, it is scarcely possible even with a large and well equipped staff to keep pace with the constantly increasing demands for photo- zincographed maps of all kinds. The process used in this country is almost identical with that in use at Southampton, the only variations being those required by the climate. Considerable difficulty has been experienced in adapting the process to the Indian climate and also in obtaining suit¬ able original maps, but now that the requirements of the cli¬ mate and of the process are better understood and the know¬ ledge I gained in Europe is being turned to account, the difficulties have greatly diminished and I venture to hope that in a short time the pliotozincographed maps issued by the Indian Survey Department will not be inferior to those turned out elsewhere. In conclusion I trust that due allowances may be made for any shortcomings when the extent of the subject and the limited time at my disposal are taken into account, and I hope that this first mission of a British Officer to the Con¬ tinent for this object may be followed by others, for I feel convinced that great mutual advantages must accrue from such interchanges of knowledge and information, and if this report should contribute to this result, I shall feel that my labors have not been in vain. J. WATEBHOUSE, Lieut ., B. A ., In charge Photographic Branch , Surveyor General’s Office. Calcutta ; September 1869. R E F O R T ON THE CARTOGRAPHIC APPLICATIONS OF PHOTOGRAPHY. CHAPTER I. FRANCE. PARIS. I,—TOPOGRAPHICAL DEPARTMENT OF THE MINISTRY OF WAR. The Topographical Department is the sixth branch of the Ministry Topographical ... . ... Department. of War. It is installed in the Depot de la Guerre at Paris, and is divided into two offices. The operations carried on in the first comprise the geo- detical and topographical operations for the execution of the new map of France; preparation and arrangement of the topographical data for all maps, drawing and engraving all the maps, and correction of the copper plates; military photography; galvanoplasty applied to the reproduction and correction of the engraved copper plates. In the second, the opera¬ tions for printing the maps and lithographing the maps of Departments. The sheets of the Atlas of France are all prepared here, and also all maps required for military purposes or to illustrate campaigns, &c. The plans of towns are prepared under the direction of the Municipal authorities, and not by the War Department. The staff of the Department did not appear to be very large, but a great deal of work is given out to private individuals, and most of the printing is done at the Imprimerie Imperiale. The mode in which the maps are prepared differs somewhat from that adopted in England, in that they are drawn by hand on paper in full detail before the Engraving is commenced. Photographs are made of these drawings, and are touched up with neutral tint in order to give more relief and show the engraver the exact effect required. Maps of France . The new Map of France comprises 274 sheets on a scale of Maps of France. 1 : 80,000 (1 inch=l*26 miles). The publication of it was commenced in 1833 and 258 sheets have been published. REPORT ON THE CARTOGRAPHIC IPranee. Drawing Branch. Eneraving on Copper. M. George’s system of correcting engraved copper plates. A very full account of the geodetical and other operations connected with the triangulation and laying down of this map has been published in the 6th, 7th, and 9th volumes of the “Memorial du Depot de la Guerre. 1 ” The other general maps published by the Depot de la Guerre are a reduction of the above maps to a scale of 1 : 320,000 (1 inch — 5*05 miles) in 32 sheets, of which 25 have been published ; and a series of maps of the Departments in 41 sheets on the scale of 1:80,000 by transfer on stone. Besides these, several miscellaneous maps have been published, among them maps of Algeria engraved on copper to the scale of 1 : 1,600,000, (1 inch —25*25 miles) in two sheets; and engraved on stone to the scale of 1 : 400,000 (1 inch = 6*31 miles) in 6 sheets. . ' f Drawing Branch . About 20 draughtsmen are employed in drawing the maps for engrav¬ ing, they are beautifully executed, but take a very long time, as every detail is drawn just as it should be engraved. In order to guide the draughtsmen and secure uniformity, a very complete set of conventional signs has been published in which the styles for four scales, 1 : 10,000 . 1 : 20,000 ; 1 : 40,000; and 1 : 80,000, .are shown side by side, it also includes a fully detailed sheet of alphabets, &c., and specimens of hill shading on each scale. JEng raving on Copper . The method of engraving on copper presented no novelties, being very much the same as at the Ordnance Survey Office, South¬ ampton ; but there are not such beautiful machines for laying off margins, &c., nor is so much use made of the method of stamping the ornament. The outline and rivers are first put in, then the letters, and finally the hill shading. This department is under the direction of M. George, who has in¬ vented an extremely ingenious and practical system of correcting en¬ graved copper plates by cutting out the parts to be corrected, and then filling up copper on the plate itself by means of a small galvanic battery. The great advantages of this process are, that the plate is not damaged as in the old process of hammering or knocking up, and it is infinitely more economical and quicker than the ordinary process of scraping the detail from the relief plate and then producing a new plate by electrotyping. I was told that the process was only one-tenth the cost of the old method of scrap- 2 Plate I. FCg. 3. APPLICATIONS OF PHOTOGRAPHY, ing the relief.* The operation is a very delicate one,, and requires much care and skill; when properly performed the surface of the plate should be perfectly flat and not a line of the surrounding parts should be touched. I saw several specimens of proofs taken just after the cor¬ rections, in which there was not the slightest trace of any damage on either side of the corrected parts. As M. George was kind enough to let me have the opportunity of learning the process, I went through all the operations practically and with tolerable success. The modus ojoerandi is as follows:— The copper plate is thoroughly cleaned, and covered with a thin varnish composed of bitumen dissolved in turpentine, applied with a brush, it must then be put aside for some hours, till the varnish is quite dry. The parts to be corrected are cut out with a sculper, leaving a good square edge without raggedness; these cuts are then surrounded with a strong stopping-out varnish made by dissolving bitumen in benzine or turpentine, and applied with a small brush, using very little to trace the contour, so as to avoid all chance of getting any on the naked copper, which would ruin the result. When the contour has been traced all round to within about the fiftieth part of an inch from the edges of the cut, more may be used, and the part to be corrected is sur¬ rounded for about an inch all round. This varnish does not take long to dry, as gentle heat may be applied to quicken it. The protected parts of the plate are then covered with wax, which is melted in a little copper pot over a spirit lamp, and applied with a stiff hog's hair brush, using some little friction so as to get an even coat of wax about one- fifteenth of an inch thick. A little suet is added to the wax to make it softer and less friable. Care must be taken to turn the plate so as to avoid passing over the cuts with the brush full of wax, and one corner of the plate must be left bare to make the connection. A trough is now formed on the plate by putting a wall of wax about 1J inch high round the work; this is done by bending round one edge of a strip of bordering wax about 1J inch wide and \ inch thick and passing it over a flame till it is soft; it is then applied to the plate and dabbed down with a wet wooden dabber (see plate 1, fig. 9); if necessary another piece may be taken to finish the wall, and the end of the strip is heated and then pressed in close contact with the other end already applied, and worked together with the wet finger; the joints * An extract of a report on the process by Marshall Vaillant, Minister of War, will be fonnd in Appendix A. % Paris. REPORT ON THE CARTOGRAPHIC France, being made complete, the plate is placed on four supports so as to be perfectly level; a saturated solution of sulphate of copper is poured in to a depth of about J inch or more, and the cuts are well washed out with a syringe in order to remove the bubbles of air which are liable to form in the corners. If the cuts have been made for some days, and the surface of the copper is oxidised, it must be cleaned with the aid of the battery; to do this a Bunsen battery is placed on a suitable support near the plate, the wire from the zinc plate is conducted into the trough and the carbon plate is placed in connection with the polished surface of the copper plate, aud in a few minutes the effect is produced. Ordinarily this is not required, but only when the cuts are a day or more old or some special oxidising influences may have been at work; however, if any doubt exists, it is better to perform this operation as it takes but little time, and makes the adherence of the deposited copper much more certain. The plate being now ready, a little porous-cell about 5 centi¬ metres, (2 inches) deep, and 2 centimetres, (|f of an inch) in diameter, is placed in the solution of copper on the wax ground at a distance of 6 inches or thereabouts from the cut; it is better to begin at a distance of 6 or 8 inches, and then when a sensible deposit has formed to bring it in closer to from 4 to 2 inches. A rod of zinc, about 1 centimetre (f of an inch) in diameter, and 6 centimetres (2§ inches) in length, to the upper end of which a strip of thin copper has been soldered, is placed in the porous cell (fig 7). The other end of the copper strip must be brightly polished as also the part of the plate where the connection is to be made, and the end of the strip kept in its place by means of a small weight. At the last moment a very weak solution of sulphuric acid (about 30 drops to a quart of water) is poured into the porous-cell from a bottle with a bent tube in the cork, the action then commences and should be allowed to go on slowly. (For the general arrange¬ ment see fig. 1, plate 1). The essentials of the first part of the process are that the surface of the copper on which the deposit is to be made must be perfectly clean, the slightest trace of grease or oxidation being sufficient to cause the non-adherence of the deposit. The acid solution must be very weak, the slower the operation is performed the better. The copper solution must be kept at saturation, by placing crystals of sulphate of copper round the cuts if they are extensive. The object is to obtain a very fine deposit of copper which shall adhere perfectly to the cut surface of the plate. 4 APPLICATIONS OF PHOTOGRAPHY. The time required to produce the proper deposit varies considerably, from 18 to 24 hours is generally ample time, but when operating on large spaces the deposition must be conducted very slowly, and from three to four days may be required. The depth of the deposit is guaged with a little instrument (fig. 8) consisting of a steel blade ending in three prongs of equal length. By placing the middle point on the deposit it is easy to see its thickness, from the distance between the side points and the plate. When the deposit has been found sufficient the porous cell, &c., are removed, the sulphate of copper solution is poured away, the wax border is taken off, and the wax ground is removed from the plate by heating it and scraping off the wax with a wet wooden scraper (fig. 10). The varnish is removed by further heating the plate and wiping it off with a rag, the plate is then washed with turpentine, and when clean is ready for filing. The parts cut out will now be found covered with an irregular deposit of metal, their shape being marked by a depression, round which rises an irregular raised edge surrounded by little knobs of copper (fig. 4). On the parts cut out the adherence is complete, but the raised edges and outside knobs being separated from the plate by the layer of varnish do not adhere nor do they damage the lines they cover up. The deposit must now be removed so that the new surface may be level with the rest of the plate. The first thing to be done is to take off all the little knobs of copper which may have formed in consequence of the wax or varnish being too thin in some parts, they have no adherence and are easily removed with the point of a burnisher. Pieces of paper having the under sides rubbed with the bordering wax are fixed on each side of the corrections (fig. 5); the greater part of the deposit is then removed with a fine flat file, about 10 inches long, with the tang turned up for greater convenience in holding (fig. 11). When the filing has been continued till the deposit is but little thicker than the paper on both sides, the paper is removed, and the remaining deposit is carefully scraped away with a sharp three- edged scraper well supported on the fingers so as not to damage the surrounding detail. After a short time the non-adherent parts surrounding the cor¬ rections will come away, and a very little scraping with the flat of the scraper will complete the operation. The copper plate must be constantly turned while being scraped so as not to work the place into a hole. This Paris. REPORT ON THE CARTOGRAPHIC France, Electrotyping. Mode of preventing adherence for incised plates. For plates in relief. operation requires great skill and some practice in the use of engravers' tools; if it is properly performed the surface of the plate should be quite flat, and yet none of the surrounding work should have been touched by the file or scraper. After the scraping is finished, the surface is restored by rubbing it with charcoal, and the plate is ready for re-engraving. From what I have seen and heard of this process I consider it of great practical utility and capable of superseding all other modes of correcting copper plates. It is a question whether it would always be worth while using it in place of the more rapid method of “ knocking up ,” but in cases where the plates frequently require extensive correction its value is undoubted. I believe it has been objected to on account of the uncer¬ tainty of obtaining adherence, but if due precautions are taken, and the cut surface of the metal is cleaned before commencing, by means of the reverse action of the battery, I am assured the process is certain. I desire here to tender my acknowledgments to M. George for his kindness in allowing me an opportunity of going through the process myself. Electrotyping, In order to make the electrotype copies of the original copperplates, there is an electrotyping apparatus consisting of a Smee's battery composed of four pairs of zinc and platinised silver about one foot square. The de¬ positing troughs are vertical. The deposit seemed very good and even, and is made at the rate of 1 kilogramme or lbs. a day. It takes 13 days to deposit an ordinary full sized copperplate, the weight of the plate being 13 kilogrammes or about 30 lbs. The plates are much thinner than is usual in England where the weight is 44 lbs. In order to increase the conductibility of the depositing bath of sulphate of copper, sulphate of soda is added in the proportion of 1 per cent. To prevent the adherence of the matrix and electrotype copy, the matrix is heated over a gas stove, and when thoroughly warm, a little white wax is rubbed on with fine rags till no trace of greenness or dirt appears on them, the plate being kept warm during the whole operation. This method is not so suitable for plates in relief which are treated as follows A little tripoli is put on the plate, some of the following solution is poured on, and the whole well rubbed with a stiff brush ■ Nitrate of Silver ... ... ... 1 part. Cyanide of Potassium ... ... 10 „ Water ... ... 100 „ 6 APPLICATIONS OF PHOTOGRAPHY. The plate thus receives a fine coating of silver and is ready to he Paris, placed in the depositing trough. I noticed that this process was very generally adopted on the Continent. Enfacing Copper Plates with Steel. In order to protect the surface of the copper plates and render them Enfacing with capable of giving off several thousand copies without deterioration, they are enfaced with a thin coat of steel by a process invented by M. Joubert. I observed that it was almost universally used on the Continent by all large copper-plate printers, and was told that it was extremely advan¬ tageous w T here large numbers of copies are required from electrotyped plates, as instead of yielding only a few hundred good copies, they can thus be made to yield many thousand equally good. When worn out, the coating can easily be replaced by dissolving off the steel and repeating the operation. A full description of the theory and practice of the process may be found in Ure's Dictionary of Arts and Manufactures under the head “ Engraving.” The following is the mode of performing it practised at the Depot de la Guerre :— A trough is filled with a solution of sal ammoniac, about 1 part of salt to 40 parts of water, more or less according' to the activity required. A plate of iron is put in and connected with the positive pole of the bat¬ tery, and the plate of copper to be enfaced is connected with the nega¬ tive pole. The battery generally used consists of two or more Bunsen's cells (see fig. 12, plate I). Before commencing, the copperplate must be most carefully cleaned with solution of potash, followed by dilute sulphuric acid applied with a soft brush, but no powder must be used or there would be a danger of blocking up the lines. The operation requires two or three hours for its completion. The plates when steeled require some little care to prevent their being rusted, and when put away must be covered with grease or wax to preserve them from damp. Copper-plate Printing . The copper- plate printing room offered no novelties, there was one Copper-piate x A . printing. copper-plate press of the ordinary pattern. The plates were placed on gratings and heated with charcoal while being inked. 7 France. Photographic Branch. General arrange¬ ments. REPORT ON THE CARTOGRAPHIC Photographic Branch. The Photographic Branch is situated at the top of the building occupied as the Depot de la Guerre. The dark rooms and laboratories are large and commodious, and there are many of them. There is no glass¬ house properly so called, most of the work being done in the open air, but there is a covered room partially glazed, in which work can be carried on in wet weather or in winter. The arrangements struck me as efficient though simple and inexpen¬ sive, and under suitable circumstances they might be adopted with advantage. For ordinary working purposes there are two very large cameras which are placed under a permanent shed on the roof of the building, the stands on which they are placed do not admit of any adjustment in altitude or azimuth, but they run backwards and forwards on rails. The plans are placed in the open air on stands which run on rails and when not in use are run back into closed wooden sheds to protect them from the weather (see fig. 1, plate II). Adjoining the roof-terrace is a long room in which is placed a camera on rails, similar to the others; a plan board is fixed on the opposite wall and a space of about 9 feet of the roof above it, and of the open side is glazed with ground glass; the inside of the room is painted a bright white, and there appeared to be plenty of light. From this room two entrances lead into four spacious dark rooms painted black and lighted with yellow glass windows. They are furnished with tables and large sinks; water is laid on in each room and the plates are washed with a rose-jet attached to a caoutchouc tube fastened on the tap. The rooms for silver printing are on a lower floor and in much the same style, but fitted up for their special purpose ; on the same floor are the rooms for the officer in charge, store-rooms, plate-racks, &c. Horizontal baths are used for sensitising and developing the nega¬ tives, and are made of thick sheets of plate glass let into varnished wooden frames. For coating large plates with collodion, a very handy instrument is used. The plate is placed on the four wooden arms and may be moved in any direction on a ball-and-socket joint by means of the long handle. 8 psLMng as. PM(M , <0>©3S.AFH2(3 AIEIBAjr®3EMiESS'TS AT fEIlS DISFOIT S)3S 3LA ©WSIEmU, FAMg. Fig, \.Plan of Roof Ter race , fyc. Fig. 2 Rear and Side Elevations of Flan stand . APPLICATIONS OF PHOTOGRAPHY. The processes employed for taking the negatives are very similar Paris, to those in use at Southampton. There are, however, two modifi¬ cations which I consider valuable; these are the use of solution S?SJ S Nega- of gum arabic as a final wash before the plate is dried and varnished, Uves ‘ and the use of dilute acetic acid to clear the plate, if it should appear yellow after the action of the hydrosulphate of ammonia. The following are the formulae for the solutions used in the produc¬ tion of the negatives Cleaning the Glass Plates . A mixture of tripoli and alcohol, as thick as cream. cleaning Plates. Collodion . (Prepared at the Depot.) Pyroxyline Alcohol Ether To 1000 parts of the above add— Iodide cadmium Iodide ammonium Bromide ammonium Bromide cadmium 30 parts. 1000 „ 2000 „ 2 parts. 7 „ | part. \ ■ 2 5J Nitrate Bath. Nitrate of silver ... ... ... 100 parts. Water ... ... ... 1000 „ used in a horizontal trough. Developer. Protosulphate of iron Acetic acid Alcohol Water used in a horizontal trough. Fixing. Cyanide of potassium Water ... ... applied after developing. Intensifying Solution. Pyrogallic acid Acetic acid Water ,,, , 70 parts. 70 „ 40 „ 1000 ,, 3 parts. 100 „ 5 parts. 80 1000 u » Collodion. Nitrate Bath. Developer. Fixing, Intensifying Solution B 9 REPORT ON THE CARTOGRAPHIC France. Re-intensifying Solution. Blackening Solution. Apparatus. Cameras. Lenses. Support for Plans. Re-intensifying Solution, Bichloride of mercury ... ,,, .. ... 300 parts. Water. 1000 „ Common salt is added ad libitum to increase the solubility of the mercury, which it does in a remarkable degree; but I have been told that such a solution is very deleterious to the health of the operators, unless great precautions are taken. Blackening Solution . Hydrosulphate of ammonia. 250 parts. Water 1000 „ Should the lines appear yellow or stained after the application of this solution, the plate is washed with very dilute acetic acid, which clears them and restores their transparency, but at the expense of the general density. This would frequently be useful and save many otherwise good negatives. After the application of the above the plates are well washed and a solution of gum arabic is poured over them, which prevents the film from splitting or peeling off while drying, and also acts as a varnish if only a few prints are required ; they are then dried and varnished if necessary. For holding large plates during the last operations a wooden cross is used which enables them to be easily handled and washed. Apparatus. There are three large cameras of Paris make, in use, they are on the bellows system, and are fixed on strong firm tables, without any adjust¬ ment. The lenses in general use are Dallmeyer's triplets, but for enlarging a globe lens by Hermagis is used. The advantages of this lens for the purpose are that it gives a flat field without distoition, includes a very wide angle, and has a short focus. The support for the plans is entirely of wood. It consists of an ordinary upright easel, with grooves in the sides, in which a frame carrying the board may be raised or lowered as required by means of a screw. The plan board is attached to the sliding frame with hinges, which permit motion round a central axis, so that the board may be set perfectly vertical. The plan to be copied is put into an ordi- 10 APPLICATIONS OF PHOTOGRAPHY, nary photographic printing frame, which is clamped firmly to the board. The stand travels on rails. (See fig. 2, plate II). Printing Process . The only process I saw in use for printing the photographed B Jy e £ ve maps was a rapid silver-printing process by development. It possesses lo P ment - several advantages over the ordinary silver-printing processes, and is more economical in time and chemicals. I was told that 30 or 40 prints could be made in an hour from one negative. Captain de Milly informed me that he could not tell me the details of the process, as it was a secret; but I have every reason to believe that it is very similar to that I saw at Brussels, of which the details are given in extenso at page 45. This process will be of much use on occasions when a silver-printing process must be used, such as when only a few copies of a subject are re¬ quired as guides for engravers or similar purposes, or when the original is colored and cannot be reproduced in printing ink; and also in cases when a great number of proofs are required at very short notice. In the Depot de la Guerre this process is considered to possess several advantages over photolithography in rapidity and certainty, and conse¬ quently, as far as I could observe, it is used almost exclusively. I was told that many experiments had been made in photolithography, but it was found not to answer the purpose so well as the rapid silver-printing. A great proportion of the work executed here seemed to consist of Ke . aso ?s for not ° A 1 using Photo¬ enlargements from printed maps; it is not easy to produce such enlarge- lith °s ra P h y- ments perfectly sharp, and therefore a silver-printing process will give more presentable results than photolithography. I saw some results of their experiments in photozincography, which were very good, and I am surprised that no process of this sort has been adopted. I have since learnt that a process of photo-engraving has been adopted and used extensively. I am indebted to Captain de Milly, the Officer in charge of the Photographic Branch, for much useful information and kind assistance. II.—APPLICATION OF PHOTOGRAPHY TO MILITARY SURVEYING. For some years past some attention has been given in France and Application of Germany to the application of photography to military surveying, and ? Iilitar y survey* several plans have been proposed for the purpose with more or less success. At present, as far as I could learn, there are two systems worthy of attention; one the “ Planchette Photographique” or Photographic Plane Table, an invention of the late M, Auguste Chevallier of Paris ; the other 11 REPORT ON THE CARTOGRAPHIC France. a more simple system published by Colonel Laussedat, of the French Engi¬ neers, who proposed to make use of the ordinary photographic apparatus, modified by the addition of an instrument for measuring angles. A similar method has been employed by Herr Meydenbauer, an architect of Berlin, who has published a pamphlet on the subject, a translation of which will be found in Appendix E. Several surveys have been made by both methods, and great exactitude and correctness are claimed for them by those who have actually executed surveys ; but, at the same time, officers of experience told me that, though very correct in theory, the methods were not considered practical. I should have liked to have seen an experiment in the field with both methods compared with a survey executed in the ordinary manner, but the opportunity did not offer, as M. Chevallier died at Toulon during the time I was at Paris and Herr Meydenbauer was not in Berlin at the time of my visit. Advantages of The advantages of the photographic over the ordinary methods of the photographic . . , over the ordinary surveying appear to be— methods of Sur- . . , veying. 1. That instead of obtaining at each observation one point only, an almost infinite number of points are obtained, many of which can be used and thus, fewer observations being required, the work is very much shortened. 2. —The great advantage they possess is, that ail errors of reading and noting the observations are eliminated. The photographs accurately register the images of all the objects visible from the point of station, none can be left out, and all are in their proper relative position. The distortion, incidental to the use of lenses, can be corrected by calculation, and with good instruments would not cause greater errors than are caused by the difficulty of reading angles exactly with the ordinary instru¬ ments. 3. —By these methods one operation serves both for the planimetry and for the levelling. 4. —In the system of Laussedat the photographs obtained, being taken in the usual way, can be used as ordinary views to give a good idea of the nature of the ground and the general appearance of the country. This use cannot well be made of the photographs obtained by Chevallier^s system, because the views are in the form of sectors of circles, and the images of objects are distorted; but by practice, however, many useful indications may be obtained even from these. Disadvantages. The disadvantages are only those incidental to the imperfection of photographic lenses and apparatus, and to the difficulties attending their use. If a lens could be obtained which could be depended on to give a 12 i APPLICATIONS OF PHOTOGRAPHY. geometrically true perspective view,, the system of Laussedat would be Paris, perfect. Dallmeyer’s “ Rectilinear ” Ross* Falk in intaglio and in relief, and I also saw their plates. They were also establishment, good enough to give me a general idea of their process, the principle of which is as follows A glass plate is coated with a mixture of bichromate of potash and gelatine, dried and exposed under a negative of the engraving to be re¬ produced. The exposed plate is then plunged in water; the parts of the gelatine coating which have not been exposed to light swell up and rise in relief. A plaster cast is made from it and shows the reverse ; the black parts of the negative appear hollow j the transparent parts, that is to say, the lines of the drawing, are in relief. This plate is, therefore, a matrix ; a cast in wax is taken from it, and by electrotyping the wax mould a 85 REPORT ON THE CARTOGRAPHIC Prussia. copper printing block is obtained, from which it only remains to cut out the clear whites with a gouge. In a somewhat similar manner copper¬ plates may be made for printing in the copper-plate press. I also saw a great many zinc plates in relief, which were very good, but could not find out by what means they were produced. 86 APPLICATIONS OP PHOTOGRAPHY. Saxony. CHAPTER VI. SAXONY. DRESDEN. I—TOPOGRAPHICAL BUREAU. On my way from Berlin to Vienna, I stopped at Dresden and called upon Colonel Carlowitz, the Chief of the Staff, who very kindly accorded me permission to visit the Topographical Bureau, and gave me an intro¬ duction to Major Volborn of the General Staff, who very obligingly showed me over the whole of it. The Topographical Bureau is not set up on a very large scale, as very J^| l J aphical few maps are executed there ; but the work turned out is extremely good. The topographical map of Saxony is engraved on copper to the scale of 1:100,000 (-633 in.=l mile), and is in 28 sheets. The engraving is beautifully executed, but the plates are engraved entirely in firm lines with the graver instead of the hachures being etched. This gives a somewhat hard appearance to the darker mountains, and requires a very long time to execute, some of the quarter size plates taking more than a year to engrave. The survey is not yet completed. I saw here an original manuscript map of the whole of Saxony to the scale of 1: 57,600 (IT in.=l mile) drawn entirely by Major Obereit, of the Engineers. The drawing was magnificent, but the general effect was too dark. This map has also been engraved. Lithography is not practised here at all, nor is there a printing aud establishment; any work of the sort is done in the town. There is a priuting - small establishment for printing copper-plates, containing one press, but at the time of my visit nothing was going on. Photography was formerly made use of, but has been abandoned lat- Photography, terly, and I was told that there was nothing to see, as the apparatus and arrangements were out of order. I saw the arrangements for electrotyping : the depositing troughs Eiectrotyping. were vertical as usual, and the batteries in use were on Smee's principle. I could not see the instruments in use for surveying, as they were surveying out in the field, but the system is very similar to the Prussian. survc^ ents aud 87 REPORT ON THE CARTOGRAPHIC Austria. CHAPTER VII. AUSTRIA. Military Geographical Institution. Maps of the Austrian Empire. VIENNA. I.—MILITARY GEOGRAPHICAL INSTITUTION. All the operations connected with the construction of the general topo° graphical and cadastral maps of Austria are carried on in the K. K. 31ili- tarisch Geographisches Institut, or Imperial Royal Military Geographical Institution, under the direction of his Excellency the Lieutenant Field Marshal Yon Fligely, by whose kindness I was enabled to see everything that was to be seen, and received full information on all the processes in use. The Military Geographical Institution was founded about the year 1807 by Napoleon I at Milan and in the year 1833, when Italy came under the Austrian dominion, it was transferred to Vienna, and installed in the building occupied by the Ministry of War, but in a short time it was found that there was not sufficient room, and so in 1842 the present building was erected. The object of it is the execution of the maps of the empire, and collection of all the materials which may serve for the construction of terrestrial and marine maps, and the publishing of these maps by engrav¬ ing or lithography. In 1851 the Emperor Francis Joseph enlarged the establishment by creating a corps of military geographers. Officers come from various regiments and remain under instruction for two years, after which they are sent into the field. The usual number of officers present in the Institution is 25, but at times the number is increased. The establishment is complete in itself, and comprises the following departments :— Topographical Drawing Military Drawing Military Mapping Military Geodesy Computing Office Lithography. Engraving. Printing. Photography. Galvanoplasty. Maps of the Austrian Empire. The maps published by the Austrian Government are of several kinds, comprising special maps of Provinces, general maps, administra¬ tive and other maps of Hungary, town plans, route maps and hydro- graphical charts. They are all engraved either on copper or stone. ’ 88 APPLICATIONS OF PHOTOGRAPHY. The following are some of the principal Special Maps in 199 sheets, on a scale of 1 in. to 2,000 toises, or 1: 144,000 ('44 in. —1 mile). These maps are engraved on copper, and comprise maps of Salzburg, Austria Proper, the Tyrol, Illyria, Austrian Silesia, Bohemia, and Dalmatia. General Maps in 64 sheets, on a scale of 1 in. to 4,000 toises, or 1:288,000 (*22 in. =1 mile). These maps are engraved on copper, and comprise maps of Galicia (33); West Galicia (6); Salzburg (1) ; Austria Proper (2); Tyrol (2) ; Steiermark (4); Illyria (4); Austrian Silesia (4); Venetian Lombardy (4) ; Bohemia (4). Colonel Scheda's Map of the Austrian empire in 20 sheets, on copper, on a scale of 1 to 8,000 toises, or 1 : 576,000 (T1 in. —1 mile). Map of the Austrian empire in 9 sheets, on copper, on a scale of 1 in.to 12,000 toises, or 1 : 864,000 (*073 in. =1 mile). Administrative Map of Hungary in 17 sheets, engraved on stone to a scale of 1 in. to 4,000 toises, or 1 : 288,000 ('22 in. = l mile). Maps of Towns with Environs, engraved on stone— Environs of Vienna in 8 sheets, on a scale of 1 in. to 600 toises, or 1 : 43,200 (1*46 in. = l mile). Vienna and Baden in 112 sheets, 1 in. to 200 toises, or 1 : 14,400 (4'4 in. = 1 mile). Brunn (in 11 sheets) ; Gratz (9) ; Lemberg (9) ; Agraw (8) ; to the scale of 1 in. to 200 toises, or 1 :14,400 (4*4 in. =1 mile). Route Maps, engraved on stone— Austria Proper and provinces in 14 sheets, on the scale of 1 in. to 6,000 toises, or 1 : 432,000 (T46 in. = 1 mile).* Route Maps in Italy , on a scale of 1 in. to 1,200 toises, or 1 : 86,400 (-73 in.=l mile). Hydrographic Charts, engraved on copper— Atlas of the Adriatic complete in four parts. Part I. —Special Navigation Map in 22 sheets, on a scale of 1 in. to 2,430 toises, or 1 : 174,960. Part II. —Views of the Harbors in 7 sheets. Part i//.—General Hydrographic Map in 2 sheets, on a scale of 1 in. to 6,944 toises, or 1 : 499,968. Part IV ,—Portolano on Navigation, printed in Italian. Cadaster on a scale of 1 in. to 20, 40, and 80 toises. The town plans are made on a scale of 1 in. to 20 toises, or 1 : 1,440 (44 in. = 1 mile) other plans 1 in. to 40 toises, or 1: 2,830 (22 in. = 1 mile). * The two sheets comprising Austria Proper are engraved on copper. M 89 Vienna. REPORT ON THE CARTOGRAPHIC Austria. Survey. Drawing of maps. Military Maps for plans of battle fields, reconnoisances, routes, &c., 1 in. to 200 toises, or 1: 14,400. (4*4 in.= 1 mile). Other Military Maps, on a scale of 1 in. to 400 toises, or 1: 28,800. Note .—1 Mile, Austrian = 4,000 toises, or 10,000 paces. 1 Klafter, Austrian — 1 toise French, or 1 fathom English. Survey. The surveys are made with the plane table on a scale of 1 in. to 400 toises, or 1: 28,800 (2*2 in. = l mile). I could not obtain any detailed information on the mode of con¬ ducting the survey, as all the parties were in the field, but I afterwards saw the instruments used consisting of an ordinary plane table and a very convenient instrument for measuring angles. It consisted of a graduated open brass semi-circle with a fixed fold¬ ing sight at each end of the under face of the diameter. On its upper face a bar carrying two jointed sights with an index traversing the graduated arc, revolves round its centre; a ball and socket joint under¬ neath the centre enables the upper surface of the instrument to be made horizontal or vertical and thus admits of horizontal or vertical angles being taken, the instrument also comprises a small compass fixed between two radii of the arc. When in use it is mounted on a suitable stand. Drawing of Maps. The maps are all carefully drawn before they are engraved, the hachures of elevated ground being completely drawn by hand before they are given to the engraver. The reductions are made by means of pantographs. Some drawings, chiefly of route maps, are made on transparent tracing transfer-paper for transfer to stone, but this method is not much used, as the method of engraving on stone is preferred. Another reason of this is the difficulty of obtaining a good transfer ink which will admit of a subject being put down on stone after an interval of some months between the commencement of the drawing and its completion. The following autographic ink has been found to keep tolerably well parts. White Wax Mastic ... Marseilles Soap (Oil) Tallow or Suet Shellac Lamp black ... To prepare it.— Take a large iron pot with a cover. First melt the wax, soap, and shellac ; when the mixture commences to bubble up, put in the mastic, and when it is melted, put in the tallow; when the mixture again begins to 90 jj part. APPLICATIONS OP PHOTOGRAPHY, bubble up, put in the lamp black and leave it till it takes fire ; let it bum Vienna, for five minutes; then put on the cover and put out the fire. Pour it out into suitable moulds. When required for use, it is well rubbed down with distilled water, and worked with the finger to obtain perfect smoothness. Engraving on Copper, The Austrian maps are extremely well engraved, but the methods Engraving Q n in use are the same as usual. Everything is done with the graver, or dry c ° ppcr ’ point, and the method of biting in with acid is never used. For correcting copper-plates two processes are used. When the Correcting *111 . copper-plates. corrections are small and unimportant, the part is knocked up m the usual way, but if the corrections are of any size or extent, they employ a method very similar to that of M. George at Paris, already described. It is as follows The copper-plate is first thoroughly cleaned, and then rubbed with a solution of— Nitrate of Silver ... ... ... ... 1 part. Cyanide of Potassium ... ... ... 10 parts. Distilled Water ... ... ... 50 „ Some powdered tripoli is sprinkled on the plate, a little of the solu¬ tion is poured on, and the whole well rubbed with a brush or rubber. The silvering is also carried round the back of the plate for about an inch or so, in order to prevent the adherence of the plate to the copper frame in the depositing trough. When the plate is entirely silvered, it is well washed with water and dried in saw-dust. Care must now be taken not to touch the silvered surface. The parts to be corrected are then cut out with a lozenge graver. If there are a great many corrections to be made, only as many are made at one time as can be done in one day, and then the plate is put in the depositing trough, and the rest are finished afterwards. When the parts to be corrected have all been cut out, the plate is placed in the depositing trough of the ordinary galvanoplastic apparatus, and is left for four or five days. When finished, the plate is taken out and is found to be entirely covered with copper, but the parts filled up are distinctly visible in depression on the back, and are scraped with a curved tool till the copper around them is quite thin; the sheet of new copper is then stripped off, and the corrected parts being torn out of the sheet remain in slight relief on the plate ; the extra deposit must then be scraped down with an en¬ graver’s scraper till the surface is perfectly restored. 91 REPORT ON THE CARTOGRAPHIC Austria. Electi’olyping. This process I do not consider quite so good as that of M. George; it requires a longer time, takes up room in the electrotyping apparatus, and there is a very great risk of having* the copper too hard by an admix¬ ture of iron which makes it very difficult to cut with the graver, (this objection only applies to the peculiar electro typing apparatus in use at the institution) ; it is also more wasteful, so much more copper being deposited than is ultimately required. Electrotyping . The electrotyping arrangements were very simple and differed from anything of the sort I had yet seen in requiring no battery. The system appears to have the advantage of taking up but little room and of being regular in its action, but requires care in its use, otherwise the copper deposited becomes too hard by admixture of iron. The apparatus consists of two wooden troughs fitting into one another (see Fig.4, PI. IV); the lower one is filled with a saturated solution of sulphate of copper, the strength of which is maintained by a supply of crystals contained in a small box. On the bottom of it is a copper frame fitting the edges of the engraved copper-plate, and having a band of copper attached to it which passes up the side of the box and outside it. The upper trough fits into the lower, and has a parchment bottom; it is filled with sulphuric acid and water, 1 part acid to 10 parts water, and sheets of iron about • r y / thick are laid in it so as to correspond in size with the copper-plate and a copper band is fastened to them. The original to be copied is silvered in the manner before described, and then laid face upwards on the copper frame in the lower trough; connection is then made between the copper and iron plates by screwing the band of copper in connection with the iron plates to that leading from the lower trough. The deposition ordinarily requires about 15 days for a quarter sized copper-plate. Care must be taken not to have the acid too strong, or the iron will be dissolved, and will enter into composition with the deposited copper, rendering it too hard. The process of acierage or enfacing copper-plates with steel is not used, as the number of impressions required of the engraved maps is not very great. It is also probable that the copper obtained in the above manner is somewhat harder than the ordinary electrotype copper. 92 APPLICATIONS OP PHOTOGRAPHY. Lithographic Printing. The lithographic printing rooms are well arranged. The presses in use are of a different pattern, but the principle is the same as of the Dutch presses, that is to say, the scraper-bearer is movable and falls back¬ wards on a hinge; when required for use, it is brought forward and fixed in its place by two catches, one on each side of the press. As in the Dutch system, the pressure is regulated by the feel of a screw acting on the scraper-bearer. The presses are chiefly made of wood. Leather tympans are preferred. The registering is performed with needles. For making transfers a much stronger press is used. Photography . The photographic department of the Institution is very well equipped, and the work turned out is very good. The atelier is at the top of the building, and consists of a long par¬ tially glazed room, at the ends of which are the apparatus for carrying the plans while being copied. By mechanical arrangements parts of the roof of the room just over the plan-boards can be made to slide back. There are four of these slides, two at each end of the room; in this way the direct sun-light can be admitted on to the plans and further the sides of the room near the plan-boards and in front of them for about six or eight feet are glazed. There are four large bellows cameras, on firm strong stands, running on rails, but not adapted for giving various motions ; these, however, are given at the plan stand. The lenses in use are Dallmeyer's Triplets and one of his new Rapid Rectilinear lenses, which has given such great satisfaction that I am told a second has been ordered. The apparatus for holding the plans is simple, and appears efficient. It is made of wood, and is provided with screws for giving lateral and vertical motions in the same vertical plane. The map is stretched on an iron frame, the sides of which may be extended by means of screws, and thus the plan can be stretched quite tight and smooth. In order to counteract the shadows thrown by the sun shining on the ground of rhe paper when copying, a screen of white calico is used, which rotates on a horizontal axis, and thus may be set to any angle. It is placed under the plan, and set so as to throw a strong light upwards. White screens are also used to counteract the strong side light. Vienna, Lithographic Printing. Photographic Arrangements. Cameras, Lenses. Apparatus for holding plana. 93 REPORT ON THE CARTOGRAPHIC Austria. Stopping out Frame. Negatives. Collodion. Nitrate bath. Developer. Intensifier. Fixing. For stopping out imperfections in the negatives, there is a duffing out frame of very good construction consisting of a table, at the ends of which are two uprights, on which a looking-glass is fixed on a horizontal axis, so that it may be inclined to any required angle. Above the looking- glass, the frame for holding the negative is similarly fixed, and attached to it by hinges is a frame covered with black calico, for protecting the draughtsman from light. The negatives I saw were very good and the mode of manipulation differed somewhat from that in general use. The following are the formulae used for producing the negatives:— Collodion. The collodion is fully iodised and is composed of— Etker ... 480 parts. Alcohol ... ... 480 „ Iodized with— Iodide of Ammonium ... 9 parts. Bromide of Ammonium ... 9 „ Iodide of Cadmium ... ... 9 „ Bromide of Cadmium.. . ... 6 „ dissolved in 1G parts of alcohol. Nitrate bath. The nitrate bath is of the ordinary strength , and is slightly acid; it is used in a horizontal trough. Developer. Protosulphate of Iron ... 15 parts. Glacial Acetic Acid ... 15 „ Nitrate of Potash ... ... 9 „ Alcohol ... 24 „ Water ... ..» ... 480 „ Intensifier. When the detail is fully out, the negatives are intensified with a solution composed of— Protosulphate of Iron ... 6 parts. Citric Acid ... 10* „ Alcohol at 40° ... 12 „ Water ... ... ... 480 „ adding a few drops of a 20 per cent, solution distilled water. of nitrate of silver in When sufficient intensity has been obtained, the plates are well washed and fixed with a concentrated solution of hyposulphite of soda, and, if necessary, finally strengthened with a saturated solution of bichlo- ride of mercury, and then varnished with lac varnish. 94 APPLICATIONS OP PHOTOGRAPHY Positive printing, Vienna. For printing paper positives by tbe silver-printing process, they use Positive plain salted paper, prepared as follows It is salted by being floated on a mixture of— salting solution. Common Salt ... ... ... 1 part, Water ... ... ... 30 parts, and when dry, it is brushed with a solution of— Nitrate of Silver ... ... ... 1 part. Water ... ... ... 4 parts. After exposure the prints are toned, and then fixed in a solution of hyposulphite of soda. Plioto-lithography. The following process of photo-lithography is extensively used, and Photo-ntho- . graphy- gives very good results - Ordinary albumenised paper is floated for five minutes on a mixture of— A .—Finest Gum Arabic ... ... ... 2| parts. Water ... ... ... 35 „ B .—Bichromate of Potash ... ... ... 1 part. Water ... ... ... 30 parts. The gum arabic and bichromate of potash are dissolved separately and filtered, forming solutions A and B; they are then mixed and poured into a large dish. When the paper is dry, all the gloss will be found to have disappeared It is exposed under a negative for about five minutes, more or less, accord¬ ing to the light, quality of the negative, &c., and then inked on a stone which has received a very thin coating of an ink composed of— Marseilles Soap (Oil) ... ... ... 9 parts. Yellow Wax ... ... 12 „ Tallow ... 6 „ Venice Turpentine . ... u » Lithographic Ink | composed of middle varnish 8") i ^ lamp black 6 ' To prepare it— Take the soap, cut it into bits, and put it in an iron pot ; when melted put in the wax, then the tallow; when they are all melted, pour out the mixture on to a slab of stone and grind it well; then put it back in the pot and add the Venice turpentine ; stir it well in, and then add the lithographic ink. The coating of ink is very pale, and scarcely perceptible on the paper. The inked proof is then washed in cold water with a soft sponge, the ink leaves it readily and when it is quite clean, it is well washed in clear water and placed between sheets of blotting paper to dry. While 95 REPORT ON THE CARTOGRAPHIC Austria. Anastatic process. just damp, it is transferred to stone with heavy pressure ; the stone is then washed and gummed, and charged up with soft ink and a sponge. The process seemed practical, and I saw some very good results by it, but noticed a tendency to enlargement of the lines. This, however, may have been due to the use of such heavy pressure or to the ink being too soft. I was told that a great many copies can be pulled. Anastatic Process . An anastatic process is occasionally made use of here; it is not used much, but is useful for copying maps, of which only a few original copies are obtainable. Marshal von Fligely kindly gave me the details. The following solutions must be prepared :•— No. 1.—Benzine (the purest possible) ... 2 parts. Oil of Rosemary ... ... ... 1 part. No. 2,—Caustic Potash ... 3 parts. Water ... ... 400 „ No. 3.—Weak solution of Gum Arabic. No. 4.—Wax Ink mixed with chrome yellow instead of lamp-black ... 1 part. Fluid chemical ink ... ... ... 1 „ The composition of the Wax Ink is — Marseilles Soap ,,, ... 12 parts. Yellow Wax ,,, ... ... 12 „ Tallow (Mutton) ,,, ,,, ... 6 „ Venice Turpentine ... ... „ Lithographic Ink composed of— Middle Varnish ... 8 parts 7 , . Chrome Yello w 6 „ > Take one part by weight of this wax ink and mix it with one part by weight of fluid chemical ink, i. e ., autographic ink, rubbed down in distilled water, till it is of the usual consistence for writing; grind them well to¬ gether with a spoon on a slab, and if the mixture is too thick, it may be diluted with benzine. The original is moistened at the back with solution No. 1 by means of a sponge for a quarter of an hour or so. As soon as the ink is softened, which may be tested by rubbing with the thumb-nail, the sheet is immersed in No. 2, just passed through it, and thoroughly well washed with water. It is then placed on a large stone, and the solution of gum is poured over it, and distributed with a sponge; then solution No. 4 is applied very lightly with a soft sponge in different directions up and down and across the paper till all the lines have taken the ink. The gum must be renewed from time to time if it has been removed from the paper, or else the ink will take on the white surface of the print. When the 96 applicati3ns op photography. lines have well taken the ink, which will be seen from their color, the Vienna, sheet is placed in a bath of very clean water (as the sheet will have be- come very tender by this time, it must be supported on another sheet of paper). The surface of the sheet is now cleaned with a soft tuft of cotton, and the washing is repeated in several waters till the sheet has become as white as possible. It is then transferred to stone and treated in the ordinary way. This process appears to have some advantages over Mr. AppePs, as it is not so damaging to the original. The same process is practised in the Topographical Bureau at Munich. Heliographic engraving is not used at present; some experiments HeUographio have been made without very good results, but it is considered of some importance, and will, therefore, be worked out till success is achieved. I was extremely pleased with all I saw at the Military Geographical Institution. The various departments seemed well arranged for the pur¬ poses in view, and the rooms and offices were of good size, clean, and not crowded. I have to express my warm acknowledgments to Lieutenant Field Marshal von Fligely for the exceedingly kind and friendly reception he gave me, and to Captain SchofF, the officer in charge of the Photographic Department, and Lieutenant the Baron Gustave de Leutsch, the officer who accompanied me during my visit, for the very obliging way in which they explained all the processes in use. II.—THE IMPERIAL PRINTING OFFICE. The Imperial Printing Office at Vienna has long been renown- The imperial ed for the beauty of its productions, and has been the cradle of several office. ° important improvements in the arts connected with printing ; among them may be mentioned nature printing, chemitypy, and photogal- vanography. It was long considered the first printing office in Europe, but of late years, owing to the depressed financial condition of the Empire, it has not been able to keep pace with the progress of the times ; however, it is again beginning to recover its former superiority. The Director received me very courteously, and allowed me to see all the operations of the establishment. Formerly there was an extensive pho¬ tographic department, but I was given to understand that it has fallen into disuse, but is about to be remodelled. The works executed here are the printing of the Government bank notes, stamps, and stamped paper. They also print the better class of scientific works and a great many books in Oriental languages. I was told that they receive a great deal of this work from Paris, because it can be done much cheaper at Vienna than at Paris, N 97 REPORT ON THE CARTOGRAPHIC Austria. Hot pressing. Type Printing machines. Lithographic Drawing. Lithographic Presses. Printing Bank notes, &c. The extent of the buildings is over 50,000 square feet; there are about 50 steam typographic presses, and as many worked by hand, 40 lithographic presses, and 24 copper-plate presses. About 1,000 hands are employed. Before the paper is used for printing, it is hot pressed in a self-acting steam machine made for the purpose, and requiring very little looking after. The old type printing machines are gradually being disposed of and replaced with new ones by Konig and Bauer, who were the first inven¬ tors of steam printing machines, one of the earliest being used for print¬ ing the Times newspaper in the j r ear 1814, and are still the best contin¬ ental makers. These machines have the great advantage of working without noise, and at the same time with great accuracy. I noticed a press for printing in two colors at once, which is a very great advantage, as the two colors are printed while the sheet is in the same position, and thus every sheet is printed exactly the same, which is almost impossible in any other way. This machine is pecu¬ liarly well adapted for Government documents, &c., containing an¬ notations in red or blue, which may thus be printed perfectly parallel with the text in black. Several clever artists are employed in drawing upon stone and for making the transfers for printing in colors. I saw some exceedingly delicate anatomical work in process of execution by lithography, the registering was not out a hair^s breadth. The lithographic presses were of the ordinary German and French systems. The arrangements for printing bank notes, &c., seemed good. They are printed four at a time off electrotype-plates in an ordinary copper- plate-press. Some of the stamps are printed in a very peculiar way, which is an excellent safeguard against forgery; it consists in printing in a pale buff colour, on the reverse side of them the figure of part of a leaf taken from an electrotype-plate obtained by the process of nature printing, which it would be impossible to imitate by hand drawing. A great number of stamped envelopes are made here. I was in¬ formed that, in order to encourage people to use them, the Government charge nothing for the envelopes, only charging the value of the stamp^ and yet they find it cheaper to do so, because the separate stamps are so frequently used twice over, certain people making it a regular trade to obliterate the marks and re-sell the stamps. The machinery for making the envelopes is very ingenious, but too complicated to describe. Most of the machines in use were by Wedding, of 98 APPLICATIONS OF PHOTOGRAPHY. Berlin, who, I believe, is a brother of the Director of the Royal Printing Vienna. Office there. The paper is cut into rhomboidal sheets, and from each sheet nine enve¬ lopes are cut. By this means very little paper is wasted. The envelopes have to be gummed by hand, as the machine cannot be made to gum every part of the edge of the paper as required by the Government. They are then made up into packets. Female labour is extensively employed for the gumming and packing. Electrotyping. Under the auspices of the former Director of the Imperial Printing office, Herr Aloys Auer, great advances were made in the application of electro typing to the reproduction of engraved plates, nature printing, &c., and an immense amount of electro typing was executed, but much of the work of this kind, though very fine, had no cpnnection with printing; for instance, statuettes, copies of shields, and other works of art. Of late years this has been abandoned, and the galvanoplastic apparatus is only used for the reproduction of stereotype plates, copies of engraved copper-plates, &c. It is said that there were 600 sets of electrotyping apparatus, but I do not think there are so many now in use, though it was the largest atelier of the kind that I saw. The arrangements presented some novelty. The depositing troughs were vertical. The porous cells consisted of open wooden boxes, the two sides of which were of parchment and the ends and bottom of wood. A zinc plate is put into each and serves for the deposition of two sheets of copper, one on each side (see Fig. 5, PL IY). In order to prevent the adherence of the deposited copper to the original, the plates are covered with a very thin coating of wax applied with a brush; the reliefs are treated in the same manner; and it is said to answer well. There are several machines for type founding : the best appeared to Type founding, be one in which the molten metal was forced each time against the matrix, and by the return of the machine pushed along out of the way. It worked with great rapidity. The former Director of the establishment interested himself very Photography, much in photographic processes applied to the reproduction of designs suitable for printing by the ordinary methods, but the want of funds has compelled the reduction of the photographic establishment, and consequently the apparatus is scarcely used, and the ateliers were all in dis¬ order, but the apparatus seemed good. The lenses were by the late A. Ross, of London, and Voightlander, of Vienna. I was shown a magnificent panorama of Vienna in several sheets, each of which was about one yard square. 99 REPORT ON THE CARTOGRAPHIC Austria. Zinc blocks for surface printing, Photographic Establishment of the Artillery Committee. The photographic branch is about to be re-established. The Director showed me some extremely good zinc blocks for surface ' printing. The process is practised by Herr Tomassiz of Vienna, but has not as yet been introduced into use at the Imperial Printing Office. Accompanied by the Director I went to see Herr Tomassiz, who showed me some exceedingly fine specimens printed from blocks executed by his method. He did not tell me any of the details of the process, but from observation, I believe, the following is a rough outline of it:— A transfer in greasy ink is made from a copper plate, stone, &c., on to a polished zinc plate, it is then dusted over with powdered bitumen, a border of wax is put round the plate, and it is etched with an acid solution ; when the finest parts have been etched sufficiently they are covered over and the biting is continued several times. The process is on the same principle as that of Gillot already described. I was much interested with all I saw at the Imperial Printing Office, but it is much to be regretted that it has been allowed to fall behind. It is now beginning to recover ground, and in a short time will, it is to be hoped, resume its old place as the finest Printing Office in Europe. I was told that the working profits are very large, and that after all expenses are paid, and a sum put aside for the purchase of new machinery, &c., there still remains a very large sum which is paid into the Imperial Treasury. 1 have to thank the Director and Sub-Director for a very cour¬ teous reception and much useful information. III.—PHOTOGRAPHIC ESTABLISHMENT OF THE ARTILLERY COMMITTEE. I visited another Government Photographic Establishment at Vienna, that of the Artillery Committee. I had heard much of it, but unfor^, tunately I found that the Officers in charge were on leave out of Vienna, consequently as no work was going on, I could only look at the rooms, which appeared very well arranged. There is a convenient glass room, and the apparatus seemed good; but I could see nothing worthy of particular notice. I afterwards saw some of the photographs executed here ; they were of the different field pieces singly, and also when horsed and mounted. The latter were exceedingly good and appeared to have been taken almost instantaneously. They had a large number of these photographs which were all very well executed, and I regretted the mischance which prevented me from ascertaining the methods in use for their production. 100 APPLICATIONS OF PHOTOGRAPHY. The Artillery Committee have also a Lithographic establishment, Vienna, in which copies are made of the drawings of the artillery materiel. For Lit ho g raphic r -r, i , mi establishment. printing these, there are 4 presses on the French system, lhe various forms required for use in the service are also printed here. The drawings were very well executed. I did not notice any use of photo-lithography for this purpose. IV.— PHOTO-LITHOGRAPHY IN VIENNA. Photo-lithography is not so much practised at Vienna as at Berlin, photo-ntho- but there are two photo-lithographers here who have produced some very excellent work, the one in line the other in half tone. Herr Leth, of Walfisch Gasse, has done some exceedingly fine copies Leth ’ e process, of old drawings, woodcuts, and etchings on copper by Albert Durer. Some of these copies possess a sharpness and clearness not often seen in photo-lithographs. He very kindly gave me some details of his process, which is for the most part the same as that usually practised, with the exception that he prepares his paper with the following mixture :*— Gum Arabic * P art 7 or 1 ge l at i n e. Gelatine \ 1 Bichromate of potash 3 parts. Water 48 „ I saw several of his negatives, they seemed very weak, which was owing in great measure to the color and age of the originals; notwith¬ standing this, the photo-lithographic copies were very good indeed, and Herr Leth told me he attributed it to the excess of bichromate of potash which caused the parts acted upon by light to be acted upon so strongly that they would stand the great amount of scrubbing necessary to clear up the white ground. He is now chiefly occupied with a process for enamelling porcelain, &c., and applying it to the ornamentation of China-ware, &c. Herr Reiffenstein, of the firm of Reiffenstein and Roesch, Lithogra- process of phers of Rothen Stem Gasse, has occupied himself very much with photo- Roesch. lithography in half tones, and has produced some very good results. He works in an entirely different manner from Leth, and, I believe, his pro¬ cess very much resembles that of Marie at Paris. He employs asphaltum dissolved in turpentine as the sensitive coating of his stones, and for the solvent, after exposure, turpentine, to which a little ether is added. He prints direct on to the stone. I did not see anything of the process, but saw a finished stone ready for printing, which had every detail on it with the greatest delicacy. I have to thank Herr Reiffenstein for the information he kindly gave me, and for some fine specimens of his process. 101 REPOIIT ON THE CARTOGRAPHIC Bavaria. CHAPTER VIII. BAVARIA. MUNICH. I.—TOPOGRAPHICAL BUREAU. Bu?eau. aphlcaI The Topographical Bureau at Munich is attached to the General Staff and under the Ministry of War. The Director is Colonel Weiss, of the Quarter Master General's staff, to whom I had an introduction. He kindly introduced me to Major General Count von Bothmer, Quarter Master General, who readily accorded me permission to visit the estab¬ lishment and see all the operations carried on there. Maps of Bavaria. Mapsof Bavaria. The maps of Bavaria, published by the Government, are the fol¬ lowing :— Blans of Position in 990 sheets to a scale of 1: 25,000. (2*532 inches = 1 mile.) Topographical Atlas in 112 sheets, engraved on copper to a scale of 1: 50,000 (1*26 inches—I mile.) Survey. survey. The survey of Bavaria, like that of most continental countries, is made by means of the plane table on a scale of 1 : 5,000 (12*6 in.—1 mile). The plane table sections contain the contours which are deter¬ mined by means of a little instrument invented by Colonel Weiss, which seemed very serviceable and convenient. It consists of a square plate of brass about 4J or 5 inches square, with bevelled edges graduated on three scales, one scale being repeated on two edges. One side is divided on a scale of 1: 5,000; another has a scale for measuring the plans of the slopes or “Anlagen fur Hohenstufen/'’ the other scale is for measuring the bases of slopes, and is so constructed that when laid on a plan the distance indicated on the scale divided by 4 gives the angle of inclination of the slope. On this brass plate is fixed a circular box about five-eighths of an inch deep, containing a moveable ring about 4 inches in diameter, and 102 APPLICATIONS OF PHOTOGRAPHY. supported on its centre, its outer edge is graduated in 4 divisions of 45° each, and it can be clamped at will. In the middle of one side, outside the box, containing the ring, there is a folding hair sight, and opposite to it on the other side is an open sight, at the side of which is a magnifying eye-piece for reading off the divisions of the scale on the moveable ring. Within the circular ring is an ordinary magnetic com¬ pass, similar to that in a circumferentor, which may be clamped in the usual way when not in use. When in use the instrument is fitted into two notches cut in the horn head of a telescopic walking stick, consisting of a brass rod sliding into an outer wooden case, and furnished with a clamping screw, enabling the instrument to be fixed at any height corresponding to the height of the eye of the observer. A stadia also accompanies the instrument ; it consists of a graduated staff with a sliding vane made of sheet iron, the face of which is painted half white and half red, the metal is doubled over at the top so as to form a sight if necessary. The instrument is chiefly used for taking vertical angles, but may also be used for taking horizontal angles and heights. It is made by Mechanicus Stollenreuter of Munich, and costs 35 florins, or about £3. To take an observation, the observing instrument is fixed in the horn top of the stick, and adjusted to the height of the eye of the observer, who then looks through the sights at the central line of the vane of the stadia, which must previously be adjusted to be at the same height as the observer's eye, the angle of inclination is then read off on the moveable ring. No plane table is required for this work, but only the cadastral plan. The contours thus taken are laid down on the plane table sections, and a peculiar method is adopted to give, at the same time, an idea of the relative height of the ground; The contours for accentuated ground are made at a vertical equi¬ distance of 25 feet, and are colored on their lower sides with a band of burnt sienna of medium strength. When the slope is somewhat less, the contours are made at I2J feet vertical equidistance, and for very level ground at 6J feet, and are colored in the same way but with lighter tints. This manner gives relief to the drawing and enables the nature of the ground to be seen immediately. These plans are termed “ Flur Blatter" which signifies “ field plans," or sheets, and include the boundaries of forests, fields, &c., and are in fact cadastral maps. Before they are taken into the field they are divided into 256 squares, about one inch square, drawn in red ink j the size of the sheets is about 18 inches square. Munich. Mode of repre- sentiugcontours. 103 REPORT ON THE CARTOGRAPHIC Bavaria. Plans of Posi¬ tion. Topographical Atlas. Copper plate engraving. Engraving on Stone. Maps in this style are printed by lithography and serve for military purposes. From these cadastral maps or field plans, reduced maps are made by means of the pantograph, to a scale of 1: 25,000, which are termed “ Posi¬ tion Blatter/" or plans of position. Upon them the ground is delineated with hachures drawn with fine brushes and not with pen and ink. This is the usual military map, and 24 Officers are employed in the Topogra¬ phical Bureau in making the reduced drawings. In order to make the wheels of the pantograph run with the least possible friction, pieces of plate glass underneath them, are let into the boards on which the instru¬ ment is worked. The sheets of the Topographical Atlas are engraved on copper on the scale of 1:50,000. The reductions are made from the scale of 1: 25,000 to 1: 50,000 directly on the copper plates by means of pantographs. For this purpose there are two of these instruments, the best of which works horizontally; it was made by Ulmer and Straubing, of Ratisbon, and cost about £40; the construction is extremely complicated, but the instrument works with the greatest precision. The other works vertically, and is not so convenient to use, the work to be copied being placed below the copy. The work is reduced on the copper plates in sections. The plate of copper is covered with etching ground, and the reduced outline is lightly marked with the point of the pantograph; the engraving is afterwards made with the graver. It is found that the work of engraving is easier when the outline is put in this manner, as the surface is opened to a certain degree by the point and so becomes easier to cut. No use is made of photography for reduction, except that reduced copies of the 1: 25,000 sheets are made to 1: 50,000 to serve as guides for the engravers to copy the hachures. Engraving and Lithographicprinting . The copper-plate engraving presented no novelties. The whole work is done with the graver, the method of biting in with acid not being em¬ ployed at all. The corrections are made with a hammer, or by scraping away the parts to be corrected from the galvano-plastic relief, and then making a new plate. The filling up processes have been tried, but unsuccessfully. Some of the maps and plans are engraved on stone, particularly the plans of battles, the hachures of the hills on which are drawn with a crayon and printed in brown, while the routes, names, and other details required in black are engraved on stone in the ordinary manner. 104 APPLICATIONS OP PHOTOGRAPHY. The lithographic and other maps are printed in the establishment. Munich. The lithographic presses in use are of the usual German pattern; but they Lithographic have a new one made by a machinist in the city, which is in principle the same as the French; and maybe worked by one man with the greatest ease. The pressure is regulated by means of counterpoises. Leather tympans are always used. Photography. The Photographic Department of the Bureau is not very well Photographic established owing to want of room. However; some very good work is turned out. There is a small glass house; but it is only used in winter and in bad weather, and serves to keep the apparatus in when not in use. The work is generally done out of doors on a flat terrace or on an upper story of the building. The camera and plan board are placed on a light turn-table; fitted with rails, which rotates on a central pivot. The camera is of large size, of the bellows form, and is fitted with a species of doublet lens by Oscar Kramer of Vienna; it is extremely good for enlargements up to nearly 6 times, linear measurement. The camera stand is not furnished with adjustments and is merely a firm table. The stand for carrying the plan is an ordinary wooden easel with a screw handle for raising and lowering the picture, but it has no other motions. The plan is fixed on a deal board with light wooden rods nailed down on two sides of it; the other two sides are fastened by large drawing pins, which, however, do not go through the paper, but are fixed at the sides of it, so that the edges may be underneath the heads. I saw several negatives, they were tolerably clear, but were, in my opinion, scarcely strong enough for photo-lithography; this process, however, is not much practised. The processes used do not differ much from those in general use. The collodion is composed of—• Thick solution of Pyroxyline in Ether ... ... 40 parts. Absolute Alcohol ... ... ... ... 30 „ Sulphuric Ether ... ... ... ... 20 „ to which are added 15 parts of an iodising solution composed of— Iodide of Cadmium ... ... ... 2 parts. Iodide of Ammonium ... ... ... 8 „ Bromide of Ammonium ... ... ... 4 „ Absolute Alcohol ... ... ... 100 „ The plates are developed with a solution of the double sulphate of iron and ammonia, then intensified with pyrogallic acid and silver fixed with cyanide of potassium, and finally varnished with a lac varnish to whicli some ammonia has been added, which has the effect of making the 105 Processes for producing nega¬ tives. O REPORT ON THE CARTOGRAPHIC Bavaria. Photographic Printing, Photo-lithogra¬ phy. varnish very red. Captain Albert, the officer in charge of this depart¬ ment, thinks this an advantage, but I think it is very doubtful whether it is so for negatives in line, which require altogether different conditions from those required by portrait or landscape negatives. For printing silver prints the usual process employed is the plain paper process, the paper being simply salted or prepared with arrowroot and salt. The rapid printing process by development, described in the account of the Belgian Topographical Bureau, was formerly used here, but it has been given up for some time. Photo-lithography. Photo-lithography is used to a small extent. Very good results both on the same scale and enlargements to 5 or 6 times the original size have been obtained by the process described below. It differs from the usual processes in the substitution of albumen for gelatine, which has not been found to answer here. In experimenting with albumen, I have found that the prints are liable to become stained with minute black spots, and I noticed the same to be the case in some of the prints produced here; however, the process is well worthy of trial. The following are the details:— 1. —Stout unsized paper is coated with albumen, care being taken that the latter is not acid. 2. —The paper thus albumenised is sensitized by floating it on a fully saturated solution of bichromate of potash for 5 minutes. The paper is then dried in a moderately warm place, for it has been found that if dried at too high a temperature the albumen becomes insoluble. 3. —In order to avoid wrinkling in the printing frame, the sensi¬ tized paper is placed in a cool place for half an hour before use. 4. —The print having been exposed under a negative is evenly coated with the following ink Yellow Wax ... ... ... 2 parts. Asphalt ... ... ... part. Colophony ... ... ... £ „ Venetian Turpentine ... ... ... £ „ Mutton Tallow ... ... ... „ Storax ... ... ... 4 » Chalk Printing Ink ... ... ... 2 parts. The rolling up must be done gently, otherwise the fatty substances which it contains penetrate the paper, and smudge when transferred to stone. The ink must be roiled on very evenly, and just so thick that the picture can be seen faintly through it. 106 APPLICATIONS OF PHOTOGRAPHY. 5. —The inked print is then immersed in clean water for 15 minutes. Munich, 6. -—The water is constantly changed until all the yellow chrome salt is washed out and it remains colorless. 7. -—The surface of the print is now gone over with a clean roller or with a tuft of fine cotton wool, this causes the ink to leave the paper in the unexposed parts, whilst it adheres strongly to all the exposed parts. 8. —The print is immersed in another dish of clean water ; then half dried between folds of blotting paper and transferred to the stone. 9. —The stone is then treated in the ordinary manner. I was also given another formula for a photo-lithographic process, but I did not see any result, it stands as follows * A solution of— Bichromate of Potash ... ... ... 1 part. Gum Arabic ... ... ... 6 parts. Water ... ... ... 36 „ is applied to the surface of a very level stone and dried slowly, the stone is then exposed to light under a reversed negative, after exposure it is washed with water, inked, and then prepared as for ordinary lithography. I was also given a formula for the etching preparation of plates of Printing on Tin plates.- tin which may be used in place of stone or zinc plates for printing forms and very common work; it consists of—■ Solution of Gum Arabic Muriatic Acid Gallic Acid Water ... The transferring and after-treatment of the plate as for ordinary lithography. 50 parts. 1 part. 4 parts. ... 100 are exactly the same Collection of printed maps . In the Conservatorium of the Topographical Department, there is a Collection of printed maps. very fine collection of printed maps, including almost all the modern topographical maps of most of the countries in Europe, mounted on cloth and arranged in card-board cases. Amongst others, there were several sheets of the Indian Atlas. There were also some very curious and rare ancient maps. Among them I noticed a map of Bavaria, executed by Dr. Appian in the 16th century, which is as remarkable for the style of its execution as for its general accuracy. It was cut on several blocks of 107 REPORT ON THE CARTOGRAPHIC Bavaria. Library. Photographic Establishment of Herr Albert. wood, the names being in type-metal let into the wood, and is very interesting as a specimen of early cartography. Library . The library contains a fine collection of military works in all languages ; here also are preserved some very curious old maps of America and of the world, executed by a Portuguese in the year 1511 A. D. They are remarkable for the general correctness of the forms of the countries represented, and are some of the earliest maps known in Europe. The portraits of the Kings of the various countries are given each in his own country, the series including that of Prester John, King of Ethiopia. I saw a great deal that was very interesting in the Topographical Bureau, and beg to express my deep acknowledgments to Colonel Weiss for the kindness and attention he showed me, and to Captain Albert, the officer in charge of the Photographic Department, to whom I am indebt¬ ed for a great deal of information and other attentions. II.—PHOTOGRAPHIC ESTABLISHMENT OF HERR ALBERT. Captain Albert was so good as to show me over the large Photo¬ graphic Establishment of his brother, who is one of the first photogra¬ phers in Munich, and has devoted considerable attention to the production of enlarged photographs. The enlargements I saw were particularly fine; the principle of the apparatus employed in producing them was very similar to that of Monckhoven. The method of printing presented a novelty to me. As it was a wet day the printing was being carried on in a glass house, but in order to print very slowly and lessen the contrast of some of the nega¬ tives, sheets of tissue paper were placed over them, and for vignettes they invariably used sheets of tissue paper over the negative. I was told that carbonate of soda was always used with the chloride of gold for the ton¬ ing bath, but I was surprised to hear that it could be kept for a week or more. The silver prints were washed by placing them on sloping boards under a rose jet of water, placed some feet above them, the prints were spread out singly and thus were well exposed to the action of the water. I was told that washing in this way for half an hour was sufficient. The laboratories and dark rooms seemed well arranged, and the whole establishment was very well fitted up and interesting. 108 APPLICATIONS OP PHOTOGRAPHY. Berne. CHAPTER IX. SWITZERLAND. BERNE. I.—TOPOGRAPHICAL DEPARTMENT OP THE FEDERAL STAFF. General Dufour's Topographical Atlas of Switzerland has long been the gem of European Cartography, and I was strongly recommended to visit the Topographical Department of that country at Berne. Being furnished with introductions from General Dufour and Dr. Hirsch to Co¬ lonel Siegfried, the Chief of the Federal Staff and Director of the Topo¬ graphical Bureau, I called upon him, and he very kindly showed me all that was to be seen, and gave me much useful information. Maps of Switzerland. The General Topographical Atlas of Switzerland is in 25 sheets Maps of Switzer- engraved on copper, on a scale of 1: 100,000 (*633 in.=rl mile). The Atlas of Switzerland being completed, the operations of the To¬ pographical Bureau are at present restricted to making corrections from time to time and to preparing a new map of Switzerland in 4 sheets en¬ graved on copper on a scale of 1: 250,000 (‘253 in. = l mile). Atlases of each Canton generally consisting of exact reproductions of the original plane-table sections, are also published, some being engrav¬ ed on copper, some engraved on stone, and some lithographed. The Atlas of Zurich Canton is very well got up in chromo-lithogra¬ phy to exactly imitate the original drawings; and contains 32 sheets on a scale of 1:25,000 (2*532 in. —1 mile). It has lately been proposed to publish Canton Atlases of all the Cantons in an uniform style, as exact reproductions of the original surveys, on the scale of 1: 25,000 for the flat parts, and 1: 50,000 for the elevated parts. At present they are all in different styles. In some the ground is delineated by contours alone, others also have the contours; but in order to better mark the relief of the ground a fine shade is put on the under side of the hills by means of roulettes. Some are published in two or three styles, the ground being delineated by contours, also by vertical hachures, or 109 REPORT ON THE CARTOGRAPHIC Switzer¬ land. Method of Sur¬ veying and con¬ struction of the Maps. Engraving on copper. not delineated at all, but the map is left in skeleton, showing only the roads, rivers, villages, and towns. Survey . I saw the original drawings of the plane-table sections, and the other drawings used in the construction of the Topographical Atlas. In mountainous districts, the scale of the original survey is 1:50,000 (1*26 in. = l mile), and the ground is delineated by levelled contours at an equidistance of 30 metres, intermediate contours being interpolated by inspection. In order to show the nature of the soil at a glance, the contours on ground fit for cultivation are put in with red, on barren ground with black, and on ice or snow with blue lines, every eighth contour being put in with a dotted line. The drawings are on sheets of paper about 13 \ *9 inches, and I was told that they each took about a year to complete. For the survey of the more level parts of the country, the scale is 1:25,000, the forests are put in with washes of green, vineyards with violet, and, as before men¬ tioned, the contours on cultivated ground are put in with red, and on barren ground with black lines. Copies of these original drawings have been made on a scale of 1 : 50,000 on large sheets, each containing four small ones, but the contours are drawn at an equidistance of 10 metres. From the surveys of the mountainous districts, similar combined drawings have been made on the same scale, but with vertical hachures. The execution of these drawings is very beautiful. To construct a sheet of the topographical atlas on the scale of 1:100,000, four sheets of the maps just mentioned are combined and reduced by hand, using the method of squares. These reduced drawings are magnifi¬ cent and might well be taken for printed sheets of the engraved maps. They contain every detail and serve as guides for the engravers. A new map of Switzerland is now being prepared in 4 sheets on the scale of 1: 250,000, only one sheet of this was ready at the time of my visit, and it appeared to be very well executed. Engraving . The engraving of the original plates is done at the Topographical Bureau, the ordinary system is followed, but the rocks and deepest parts of the mountains are bitten in with acid. The maps are engraved on copper-plates of the usual size, the ori¬ ginals are carefully preserved and not printed from but electrotype reliefs 110 APPLICATIONS OF PHOTOGRAPHY. are made from them, and from these again the plates for printing. The Berne, relief I saw was not silvered, but from the absence of tarnish on the plate, it is probable that a waxy composition is used to prevent the adherence of the matrix to the copy. The plates for printing are always protected with a covering of steel. The electro typing and printing of the maps is not done in the Bureau at Berne, hut at the great printing establishment of Benzinger at Einsedeln. The printing establishment of the Bureau is very small, there is only Printing, one copper-plate printing press used for trials of the plates. There is also a lithographic press of the ordinary pattern; very little lithography is done here, but for military and other purposes, where a cheap map is required, copies have been made of the atlas sheets by transfer from copper to stone. Colonel Siegfried showed me a specimen of a map printed in the ty- Maps printed in pographic press. It was done by Benzinger. The process is probably P ress - similar to that of Gillot, but the result was unusually good. Photography is not used at all. Photography. I was very much gratified with all that I saw at the Topographical Bureau, Berne, and desire to acknowledge the kind reception I met with from Colonel Siegfried. II.—OBSERVATORY AT NEUCHATEL. When passing through Neuchatel on my way to Geneva, I visited observatory at Neuchatel, Dr. Hirsch, the Director of the Observatory, to whom I had an intro¬ duction from Marshal von Fligely of Vienna. He was kind enough to show me the Observatory, and to give me some information regarding the Swiss Survey. The Observatory at Neuchatel is the finest in Switzerland, and is very well equipped with instruments of the latest pattern. The transit instrument is a very fine one. It was constructed by Transit instru- Ertel of Munich, and the objective by Mertz, the well known optician ment * of the same city; the focal length of the telescope is 6 feet, and the aperture 57 lines (Paris measure). The instrument is provided with 21 fixed vertical wires, one in the centre, and two groups of five each on each side, the wires being apart, and the groups 6 ". The times of the stars passing the wires are registered by electricity in connection with a chronograph. The eye-piece has a magnifying power of 200 times. For observing at night the wires are illuminated by a light entering from the side along the axis of the trunnions and then reflected. On 111 REPORT ON THE CARTOGRAPHIC Switzer¬ land. each side of the instrument, perpendicular to the axis of support is a -vertical circle, 3 feet in diameter, both graduated in two scales on silver, one to 2 minutes, the other to 15 minutes. The micrometer is divided into 60 parts, and by its aid angles may be read to 1 second. There are four microscopes to each circle. The zenith is taken by means of a reflection of mercury, placed below the floor vertically under the axis of the instrument. In order to ascertain the level error , that is, to see if the instrument lies perfectly horizontal on its supports or trunnions, a level is lowered by means of a sort of crane till it rests on the axis of support. This crane traverses an iron circular arc fixed in the wall of the room, and has a contrivance for carrying the level and allowing it to be disengaged when on the instrument. The support being taken away, the level remains on the instrument resting over and on the axis of support; its indications are read and registered, it is then turned end for end by means of the crane and the new readings are registered. The horizontality of the axis of support of the instrument can then be adjusted by means of fine screws, but it is such a very delicate opera¬ tion that they prefer to take the mean of the readings of the error and allow for it. The instrument is adjusted in this manner every two or three months, and the mean error is registered, but if it becomes too great, the instru¬ ment is put in adjustment. The adjustment to ascertain the azimuthal error is effected with the aid of a machine, by means of which the instrument can be raised off its axis and turned round end for end. This machine has two movements, one for lowering and raising the instrument, the trunnions of which rest on two arms, with well padded circular supports at the ends in which they fit, and the other is for turning the instrument round on a vertical axis. To test the instrument the fixed meridian mark is placed at a dis¬ tance of 11 kilometres to the south, it consists of a diamond shaped cut in stone, the vertical diagonal being marked with a black line, and is easily visible through the telescope. The other point is a gas flame placed at a distance of 100 metres to the north. This is viewed through a lens, placed in the prolongation of the axis of collimation of the instrument, which gives the effect of the light being at an infinite distance. The flame is screened in such a manner that only a small point of light is visible. 112 APPLIC ATIONS OF PHOTOGRAPHY, The distances of the axis of collimation from the meridian are then Neuchatel, measured in both positions of the instrument. For convenience, while making observations with the instrument, a couch is used, running upon rails, so that it can be moved forwards or backwards with the greatest ease. The back can be set at any required inclination, and there is a step at each end, which can be raised or lower¬ ed by means of a rack. The times of transit are observed with the aid of a sidereal clock by Winnerl of Paris. It has the latest improvements, and the seconds are registered by electricity. The chronograph, or instrument for registering automatically the chronograph, times of transit, was made by Hipp of Neuchatel. It has now been eight years in use, and registers with marvellous accuracy. It consists princi¬ pally of a cylindrical drum, round which is wound a sheet of paper which can be brought in contact with two capillary glass pens supplied with ink, one of them being in electrical connection with the sidereal clock, the other with the transit instrument, so that at the moment of observation a touch from the observer completes the circuit and puts the pens in motion. The driving apparatus is very ingenious; when the instrument is wound up a steel spring is put in vibration at the rate of 120 vibrations in a second and turns a notched wheel acting on other ^ wheels and thus turns the cylinder. The cylinder turns once in two minutes, and the lines traced on the paper by the pens are spirals. t- The instrument is put in motion before the commencement of the observations ; and at every second the first pen makes a notch in the line, the distance between these notches being 1 centimetre, thus As soon as the observation commences, the observer touches the button, thus completing the circuit and setting in motion the second pen, which then begins to mark each second with a square indentation instead of a pointed notch, thus. At the moment when the star has r passed the last wire, the observer breaks the circuit, and thus the length of the observations is exactly registered. The fractional parts r of a second, represented by the distance included between the notches marking the commencement of the observation and the first s econ( i r 1 marked afterwards, are calculated by the aid of a little instrument which enables them to be read to the 100th of a second. In this manner the exact time at which the star passed the wires, and the length of time occupied in the transit, are determined with the utmost nicety. REPORT ON THE CARTOGRAPHIC Switzer¬ land. Registry of chronometers. Chronoscope oi instrument for determining th personal equa¬ tion. To give the true time in the town an electrical clock, made by Shep¬ herd of Leadenhall Street, London, is employed. Its construction is the same as of that used at the Royal Observatory, Greenwich. The mechan¬ ism is rather complicated, but the method of correcting the time is very ingenious and was proposed by Mr. Airy, the Astronomer Royal. If the clock is found to go too fast, a long pendulum is swung from a suitable support by the side of the clock and attached to the pendulum of the clock by means of a loop of thread so adjusted that the clock pendulum shall be retarded of a second at each vibration, the required correction is then easily made by allowing the combination to swing as many vibrations as the clock is hundredths of a second too fast. If, on the other hand, the clock is too slow, the extra pendulum is shortened so as to cause the combination to vibrate of a second in excess at each vibration. This clock is in communication with similar clocks at the other observatories in Switzerland, at Zurich, Berne, and Geneva, and gives the time to numerous electric clocks in various parts of the town. By an ingenious mechanism, at 5 minutes before 1 o'clock, one of three little catches is touched, and connection is made with one wire; at one minute before the hour, connection is made in a similar manner with a second wire, and at the hour with the third, which completes the circuit and gives the time. A great number of chronometers are sent here to have a register made of their rate of going to serve as a certified record of their regulari¬ ty. They are kept for a month, and a daily register is made of the working of each, this is given to the maker, and by him handed over to the buyer with the chronometer. They are tested for their capability of bearing high temperature by being placed in a box under which a gas flame is applied, and by a simple automatic arrangement, for regulating the supply of gas, the temperature is kept at 30° centigrade or 86° Fahrenheit. Chronometers, intended for use in tropical climates are subjected to a still higher temperature. The arrangement for regulating the temperature is very clever. A long curved spring made of brass and steel combined, is fixed inside the box and its expansion or contraction by the variations of temperature, cause it to move a lever by which the neck of the tube supplying the gas is contracted or opened as required. It is found that every observer has some peculiarity about his eyes which causes him to observe a phenomenon sooner or later than other observers; some means must therefore be adopted for registering this difference, or as it is termed the personal equation , that is to say, a 114 APPLICATIONS OP PHOTOGItAPHY. calculation of the time that elapses between the actual commencement Neuchatel, of a phenomenon and its being apparent to the eye of the observer, so that it may be allowed for in all observations; some standard being arbitrarily fixed. For this purpose an instrument is used called a chronoscope, which will measure minute differences of time accurately to within the thousandth part of a second. It is worked by electricity and is too complicated in construction to describe here. To register the barometrical observations there is an automatic instru- neghter of Baro- ° . metrical observa- ment also worked by electricity and made by Hipp of Neuchatel. It is gom. on the aneroid principle, and is fitted with a roll of paper passing under two needles, one of which being fixed marks tbe middle line of the paper, the other moves according to the variation of pressure on a strong steel spring. The observations are only made three times a day; the instru¬ ment is placed in connection with an electrical clock, and, at the proper intervals, works by itself during a quarter of an hour. It registers with the greatest accuracy, ^ of a millimetre being the greatest error. In an upper story of the observatory there is an equatorial instru- Equatorial la¬ ment by Mertz of Munich. The aperture of the telescope is 6 inches Paris measure, (or rather more than 6 inches English) and its focal distance 10 feet. It is equatorially mounted on two axes at right angles to one another, so that it may be moved round in any direction without coming in contact with the pedestal on which it is supported, and by means of counterpoises and friction wheels it is kept in perfect equili¬ brium in all positions, so that the slightest touch is sufficient to move it in any direction. By a suitable clock-work movement the telescope is made to move by itself round its polar axis and follow the course of a star, leaving the observer free to use both hands. I noticed a very good apparatus for turning the dome of the room Apparatus for in which the equatorial is placed, by means of which the dome is moved dome!" e round by the exertion of a force not exceeding 2 or 3 pounds. The principle of it is to put the weight of the dome on the circumferences of the runners and not on their axes as is usual. The runners are distributed round the circumference at about a yard apart, between two circular rails of triangular section, the upper of which is fixed to the bottom of the dome, and the lower to the brickwork of the walls of the room. The run¬ ners are connected together by a circular ring which keeps them in their places. The moving power is given by a differential winch acting on rack work. This method is greatly preferable to cannon balls as they always get blocked up together. 115 REPORT ON THE CARTOGRAPHIC Neuehatel, Dr. Hirsch shewed me the levelling instruments used on the Swiss Levelling instnv surveys consisting of a level of good construction used in coniunction meats used on >’ leys Swiss sm ‘ witb a levellin & or stadia which presented some novelty of con¬ struction. The level is of a very good pattern, and is so exact that the error does not exceed 1 millimetre in a distance of a kilometre or to oho oo* It consists of a telescope with a magnifying power of 24 times, fitted with three horizontal fixed wires and furnished with a micrometer and moving wire to give the intermediate readings by inspection. A spirit level graduated in divisions of 3' is fitted above it. It rests on suitable supports and is adjusted by means of three screws, the lower ends of which are hemispherical and fit into cups of the same form, being kept in their places by notched catches. The instrument is mounted on a firm tripod stand. When in the field the instrument is adjusted for collimation every morning and evening, and the differences of the four readings are register¬ ed and the mean error noted. The observer only makes one observation at each station on the ground, instead of making forward and back observa¬ tions each time, and afterwards applies the mean error. The instrument is made by J. Kern of Aarau, Switzerland, a town noted for excellent mathematical instruments. The stadia or levelling staff is of wood, its face is graduated in centimetres with an engine- divided scale. A small circular level is attached to it at the back and also handles for holding it by, the bottom is shod with iron and has a strong iron point made to fit into a hole in a flat iron plate. This is to ensure the staff not changing position whilst being turned. I found this observatory very interesting and worthy of a more skilful pen than mine to describe the beautiful electrical instruments employed, I have to acknowledge the kindness and at¬ tention of Dr. Ilirsch in explaining the eonstruc- i ^ tion and use of the various instruments. UJ Stadia. n it 116 APPLICATIONS OF PHOTOGRAPHY. CHAPTER X. GENERAL RESUME. It may perhaps be as well to give here a general resume of the methods used on the Continent for the survey, construction, and execution of the topographical and other maps published by the various Govern¬ ments, as well as of the present state of the arts of photo-lithography and photo-engraving, especially as regards their application to the repro¬ duction of maps. Survey. The Surveys of most Continental states are made either as cadastral survey, surveys on a trigonometrical basis or from the cadastral surveys of dis¬ tricts or townships reduced and carefully corrected on the ground to a trigonometrical basis. Levelling operations are almost always carried on in conjunction with the surveys of the detail, and the contours are laid down in various styles, the equidistance varying with the nature of the ground from 1 to 30 metres. The surveys are plotted on scales varying from 1:2,880 (22 in.=1 mile) Scale, to 1:50,000 (l 8 26 in.=l mile), but the usual scale is from 1:20,000, (3T6 in.=l mile) to 1:25,000 (2*52 in.=l mile). The instruments used for topographical surveys consist almost instruments, invariably of the plane table, used in conjunction with instruments which serve the double purpose of levelling and surveying the planimetry, for instance the Belgian levelling compass, the Prussian kippregel, and the little instrument invented by Colonel Weiss of Munich, all of which re¬ quire stadia or levelling staves of various kinds. Topographical Maps. The topographical maps are reduced from the original surveys by Topographical means of the pantograph, and then carefully drawn in full detail on the aiS ‘ scale required before they are given to the engravers. A great deal of attention appears to be given to securing uniformity in the styles of drawing and very complete specimens of conventional signs and styles of drawing on all the scales in use are published. 117 REPORT ON THE CARTOGRAPHIC Scales of maps. Engraving on copper. The ground is almost invariably represented by vertical hachures. The scales in use vary from 1 : 20,000 to 1 : 320,000; the usual scales are from 1 : 50,000 (T26 in.=l mile) to 1 : 100,000 (*63 in.=l mile) for engraved topographical maps, and from 1 : 200,000 (-31 in. =1 mile) to 1:320,000 (T9 in.—1 mile) for engraved general maps; but reproductions of the original surveys on a larger scale as 1:20,000 (3T6 in. —1 mile), or 1:25,000 (2*52 in.=l mile) are often published by the cheaper process of lithography. The following table will show the scales of the principal maps, published by the Continental Governments, mentioned in the report, compared with the English and Indian maps :— Country. Survey. Topographical Map. General Map. France 1 : 20,000 1 :80,000 1:320,000 Belgium 1:20,000 1 : 40,000 Holland . 1: 25,000 1 : 50,000 1 : 200,000 The Rhine 1: 80,000 Prussia ... ... ... 1:25,000 1: 100,000 Saxony ... ... ... 1 : 25,000 1 : 100,000 Austria 1 : 28,800 1 : 144,000 1 : 288,000 Bavaria 1 : 5,000 1 : 25,000 1 : 50,000 Switzerland 1:25,000} 1 : 50,000 j 1 : 100,000 1 : 250,000 England 1 : 2,500 1 : 10,560 (6 in.=l mile) 1 : 63,360 (1 in.=l mile) India (Revenue Survey) 4 in.=l mile (1 : 15,840) 1 in.=l mile (1 : 63,360) (1 in.=4 miles) (1 : 253,440) (Topographical Survey) 1 in. = l mile (1 : 63,360) 1 in.=l mile *25 in.=l mile (1 : 253,440) Engraving . Most countries possess a map engraved on copper, and the engraving is well executed, but the methods do not differ much. As a general rule every line is engraved with the graver, instead of etching* and biting in 118 APPLICATIONS OF PHOTOGRAPHY. with acid, this has the advantage of making the plate stronger and cap¬ able of lasting longer without retouching, but it takes more time to execute, and the work looks hard and rigid. Maps on a less scale than 1: 80,000 are seldom engraved on copper. The corrections of engraved plates are usually made by “ knocking ^glived piatL up” or by scraping the detail from the relief plate and then making a new plate by the galvano-plastic process. At Paris and Vienna the cor¬ rections are made by cutting out the faulty parts and filling them up with new copper by galvanic action, which seems to be a better and more economical process when the corrections are at all extensive or have fre¬ quently to be made. The method of enfacing engraved copper plates with iron is almost Enfacingengrav- , . ed P lates with universally used, and is considered very valuable in all cases where the iron * plates are required to yield a large number of proofs. Engraving on stone is very extensively used for engraving all maps Engraving on on scales larger than 1: 80,000, and several maps on much smaller scales. St Shellac ... ... 4 „ Burgundy pitch ... 3 „ Soap ... s „ Palm oil ... ... i ounce. Lampblack ... 4 „ Wax i H Middle varnish 1 gill. Bitumen 1 5J Asphaltum ... 2 ounces. The ink B used alone has given excellent results at Southampton and in this country at Dehra and Poona. Some of it prepared at Southampton 143 REPORT ON THE CARTOGRAPHIC was found to be far too soft for work in Calcutta and therefore it is usually mixed with the hard retransfer ink. When about to ink the prints a quantity of the ink is taken and mixed with sufficient turpentine to give it the consistence of honey. A little of this is well worked on the inking slab with the roller, and an even coat of it is spread on a polished zinc plate. The prints are laid face downwards on the inked surface, a sheet of clean paper is laid over them, and they are passed through the press with a pressure lighter than is used for printing. After being passed once through the press, the prints are examined and if the coating is not perfect they are turned end for end and passed through again. Care is taken not to allow the ink to stain the back of the prints. The coating of ink should not be too thick or there will be a tendency for the lines to spread under the press. This and the following operation must be conducted in a non-actinic light. Development of the transfers . The transfers having been inked are floated in zinc trays on the surface of water at 90° till the unaltered gelatine is softened and the detail becomes clearly visible. They are then laid or^a sloping plate of glass in another tray, w r arm water is poured over them and the soluble gelatine is gently removed by washing them with a very soft sponge. There is no necessity to clean the transfers entirely at this stage, but when most of the ink has been removed they are placed in a dish of tepid water and allowed to soak for an hour or so, (if the paper is fresh the prints will not stand soaking for more than some minutes) and then washed again with the sponge very gently till they are quite clear, this is better done by day-light; they are finally washed, front and back, in a dish of clean cold water and hung up to dry. They are now ready for transfer to zinc or stone but it is better to keep them at least one day before they are transferred, in hot weather they may be kept 2 or 3 days with advantage. As it generally happens that the maps are photographed in several sections, the transfers must be joined together neatly so as to form sheets of the size of the original or any other convenient size. To ensure success in this operation, the sections must all be taken under precisely the same conditions so as to correspond exactly and a liberal margin must be allowed all round for joining. The transfers are trimmed and all parts not required to transfer are cut away or stopped out with a composition of flour paste colored with vermilion, they are then laid out face upward in their proper position on 144 APPLICATIONS OF PHOTOGRAPHY. a drawing board. Then beginning at one corner of the map a cutting line on the best of two adjacent sections is selected, the transfer is cut along this line with a sharp pair of scissors and then fixed in its proper position over the other by means of pins set in at intervals. The same operation is repeated with the remaining sections, and when they are all fitted together a little gelatine solution is taken on a fine brush and introduced between the transfers here and there, but not close to the edge of the join or there is a danger of its spreading over the lines and preventing their transfer. When the gelatine is dry, the pins are taken out and the sheet is turned over gently on to its face, the spare edges of the under-transfers are cut away to within half an inch or so of the joins, a little gelatine is passed under the join and allowed to dry and the sheet is then ready for transfer. 4.— ZINCOGBAPHIC PRINTING. The zinc plates used for printing are about 42" X 28" and of 9 or 10 13. W. guage; they are imported planished and ready for graining instead of being in the rough state and thus the toilsome and difficult labor of planishing is avoided. Graining of the plates. Before the plates can be used they must be grained in order to increase the affinity of their surfaces for the greasy ink, and render them as capable of retaining moisture as a lithographic stone. To grain a plate, fine sand is sprinkled on it and moistened with water, and a zinc muller is worked round and round with a slow consecutive rotary motion in small circles up and down and across the plate in every direction till the surface appears of a fine uniform dark grey tint. When the plate is grained, it is well washed with water to remove all traces of sand and then washed on the back with hot water so that the face may dry as evenly and quickly as possible. The best sand for this purpose is the soft yellow loamy sand called brass founders* moulding sand. Silver sand is not suit¬ able, it is too hard and is liable to scratch the plate. Before use it is carefully sifted through brass-wire sieves varying in fineness from 120 to 160 holes according to the effect required, a sieve containing 120 holes to the linear inch being generally used for map-work. While graining the greatest care must be taken to avoid getting any grit on the plate ; the mullers must be carefully washed before use and must not be put down on their faces or where any grit or dirt may attach itself to them. t 145 India. Zinc Printing Graining of the plates. REPORT ON THE CARTOGRAPHIC Treatment of zinc plates which have received transfers . Treatment of zinc platea which have received transfers, The zinc plates can be regrained and used again and again without any sensible diminution of thickness. The regraining is a very simple operation. If the plate to be regrained is “ gummed up/' that is, covered with gum to preserve it—the gum is washed off, the ink is removed with turpentine, the plate washed with water and then with a solution of the crude potash called saji in order to destroy the grease in the ink. The plate is then well washed with water and an acid solution is applied, composed of. Sulphuric acid ... ... ... ... 1 part. Muriatic acid ... ... ... ... 1 „ Water ... ... „.. ... 10 parts. This is left on for a few minutes and then well washed off with water. It is done in the open air as the fumes are very unpleasant. The plate is then grained as before described. Transferring the photo-transfers to zinc. photoSansfer? 0 When about to be transferred the photo-transfer is placed between t° zmc. sheets of damp paper and allowed to remain a short time during which the zinc plate is placed on the press and rubbed with a dry muslin rag*, two or three sheets of clean paper are then laid over it and it is passed through the press once or twice till the pressure is regulated. When the transfer is sufficiently damp it is removed from the damp¬ ing book and gently laid in its place on the zinc plate, a sheet of clean damp paper is laid over it and over that a sheet or two of dry paper. The transfer is then passed through the press once. The effect is examined by lifting one corner, and if all the ink has not left the paper, the plate is turned round and passed through the press again. The back of the transfer is then damped with a sponge and water, and as soon as the paper appears loosened it is gently removed. The plate is then thoroughly washed and fanned dry. The corrections are generally made at this stage as will be described hereafter. After the plate is touched up, it is etched with a solution of gum water, tannin, and weak acid composed of— Decoction of galls ... 1 quart. Gam water ... ... 3 quarts. Phosphoric acid ... ... 3 ounces. The decoction of galls is prepared by soaking 4 ounces of bruised Aleppo galls in 3 quarts of cold water for 24 hours, the water and galls are then boiled up together and afterwards strained. The phosphoric acid is made by placing sticks of phosphorus in a bottle of water, so that the 146 APPLICATIONS OF PHOTOGRAPHY. ends of the sticks may be exposed to the air. The etching liquid is brushed India. all over the plate with a broad brush and allowed to remain a few seconds • the excess is then wiped off with a cloth and the plate is fanned dry j when dry the preparation is thoroughly washed off with water, the plate is then sprinkled with turpentine and a few drops of water, and gently rubbed till the ink is removed; it is then damped and rolled up in the ordinary way. When printing fine close work or in hot weather the following solu¬ tion is used instead of water for damping the plate while printing. Take 24 ounces of mucilage of gum arabic, add lime water till it is neutral to test paper, then add 2 ounces of glycerine and mix well. To 2 ounces of the above solution 10 ounces of water are added, care being taken to keep the mixture neutral, otherwise it acts as an etching solution. By the use of this solution the finest detail may be printed without clogging up. Corrections. It has usually been stated that the great disadvantage of using zinc corrections, for printing is from the difficulty of correcting errors or making additions after the subject has once been put down and etched. In practice, how¬ ever, little difficulty is experienced if proper care be taken. Corrections before proving. These should be made before the plate is Corrections be- u ' fore proving. etched. Stains, finger-marks, spots and other imperfections are easily removed by means of a piece of snake-stone, slate pencil, &c. Faint lines are strengthened with autographic ink applied with a fine brush. Head¬ ings and foot notes, &c., are added by transfer from engraved copper-plates or type on transfer paper. Corrections after proving. If the plate has been etched and rolled in, Corrections after . . . proving. the following plan is adopted. The plate is covered with gum and fanned dry, the part to be altered is washed with water to remove the gum, and then with dilute nitric acid 1 to 6; the acid is washed off with plenty of water, and any required insertion is made by being transferred from transfer paper or drawn in by hand with autographic ink, the part is then etched, the gum washed off and the plate is ready for printing. An etching point may also be used for putting in detail, but in that case the plate is etched before using the point. If it is required to remove part of the work before making the corrections, the plate is fanned dry, a dilute solution of caustic potash is carefully applied to the part with a pen or brush according to the size of the alteration required. When the ink is removed the potash is soaked up with blotting paper, the gum, &c., is washed off and the 147 REPORT ON THE CARTOGRAPHIC Anastatic Pro¬ cess. part is allowed to dry. The dilute nitric acid is then applied as before and the corrections inserted. Care is taken not to allow the alkaline and acid solutions to spread by placing a card-board mask over the parts. If the dry point is used the acid is not required; the part is etched, then covered with gum, and the insertions are scratched in with the point, printing ink is then forced into the lines with a dabber, made of closely rolled flannel, worked round and round till the lines are well charged. A sheet of waste paper is laid on the plate and it is passed through the press to drive the ink well into the scratches and also to remove the superfluous ink, the remainder is removed with the gum by sponging the plate; if necessary the plate is washed with turpentine and rolled up again. If the part to be altered is large or the work has been on it a long time, it is better to grain it with a small muller and fine sand, but if this cannot be done the acid solution is allowed to act a longer time. The photozincographic process as thus worked generally gives satisfactory results, and as a rule the defects may be traced to the originals, but it frequently happens in the hot weather that the ink on the transfers softens very much and spreads when transferred to zinc, and further it becomes very difficult to print during the hot weather from the softening of the ink and the heating of the plate, which may be partially obviated by the use of stiffer ink and damping the plate with iced water, but whatever precautions may be taken, it is almost impossible to print fine work during the hot months, and thus the maps appear somewhat coarse; but any such defects are of little moment when the extreme utility of the process for reproducing all kinds of maps in a useful practical form with economy and expedition is taken into consideration. Instead of having to wait for years till the publication of the maps by lithography or copperplate engraving, the local authorities, engineers or others requiring them, can by its means obtain the most accurate maps of districts under survey within a few months after survey. Anastatic Process. This process, the invention of Mr. R. Appel of the Ordnance Survey Office, Southampton, has proved of great service in enabling facsimile copies to be printed from old engraved or lithographed maps out of print, in a very economical and satisfactory manner. The mode of procedure is as follows :— Any drawings in transfer ink or printed matter of all kinds may be transferred in this manner, but the process varies according to the age of 148 APPLICATIONS OF PHOTOGRAFITY. the subject; old originals of which the ink has become hardened and India, decomposed require a perfectly different treatment from that given to originals lately printed, and therefore before transferring any letter- press, lithography or engraving it must first be ascertained whether it must be treated as an old or as a new print, by laying the original face downwards on a sheet of clean paper and rubbing a little piece at the back of it with the thumbnail; if it gives a set off it may be treated as a new print and if not as an old print. Process for the transfer of new prints . The original is laid face downwards on some clean blotting paper Process for the ° 1 1 transfer of new and brushed over with the following solution P rints - Strong nitric acid ... 1 part. Water ... ... ... 5 parts. The best brush for this purpose is made of a flat wooden handle with a strip of flannel or blanket wound several times round it and fastened with sealing wax. The damping is continued till the paper is thoroughly and evenly saturated, when it is removed and placed between folds of dry blotting paper till the superfluous acid is removed, which will be shown by the paper appearing equally damp all over and rather damper than paper for printing. Thick papers are dried more than thin papers or the excess of acid would be squeezed out and destroy the transfer. The transfer thus prepared is then removed to a strong copper¬ plate press furnished with 3 or 4 felts, and carefully laid on a polished zinc plate prepared just in the same way as described above for photozincography, but instead of being grained it is rubbed with pumice stones and then with water of Ayr stone, and finally polished by being worked in every direction with a rubber made of a square piece of cork covered with fine emery cloth. The pressure must be regulated before the transfer is laid on the plate. The amount of pressure required is a strong printing pressure and should be sufficient to glaze ordinary paper. The zinc plate must be well rubbed with blot¬ ting paper till perfectly clean, the transfer is then laid on it face down¬ wards, a sheet of clean paper is laid over it, and the whole is passed once slowly and evenly through the press, the original is then removed ; the plate is covered with fresh gum water (not too thin) and then gently rubbed with a soft damping cloth and a little water till any particles of paper have been removed ; the plate is then gummed again and allowed to dry. 149 REPORT ON THE CARTOGRAPHIC After a few hours the gum is partially removed with a little water and the plate is charged up with the “ charging ink^ applied with a small damp sponge. The plate is damped with a rag dipped in thin gum water and the ink is rubbed with a gentle pressure all over the plate in straight lines, but in different directions keeping the plate always wet with the gam water. When the plate is properly charged,, the dirty gum water is washed off and the plate is etched with a solution of 2 ounces gum water and 12 drops of phosphoric acid, the etching is washed off and the plate is damped in the ordinary way and rolled in with litho¬ graphic printing ink. The roller used for this purpose is larger and much softer than the ordinary lithographic rollers in order that it may not be so liable to slip on the plate. This first rolling is done with rather soft ink and very little on the roller. When the plate has been sufficiently charged with ink, two or three proofs are pulled, the plate is then etched again and rolled in with a stiffer ink. If many impressions are required, the damping solution of gum and lime water before des¬ cribed is used. Process for transferring old prints. SSagoWprS!’ The first thing required is to soften the ink by steeping it in a hot solution of caustic strontia prepared by adding half an ounce of caustic strontia to each pint of boiling water, the mixture is allowed to boil for two minutes and is poured out into a flat square copper pan strongly tinned inside, and placed over a charcoal fire so as to keep the temperature at about 180°. Before pouring in the solution a sheet of paper is placed in the pan, the transfer is then laid on it face upwards and the strontia solution is poured over it. Several transfers may be put in at the same time, but care must be taken that every transfer is properly covered with the solution. Air bubbles are removed with a wooden roller 1J inches thick and as long as the original. After every impression has been wetted with the solution separately, the wooden roller is laid on one end, pressed gently down with a flat piece of wood and rolled over the prints till all the air bubbles are driven out. A piece of paper is then placed over the prints, the lid of the pan is put on and the transfers are left till the ink is sufficiently softened which may take from 5 minutes to 1 or 2 hours. The proper time is ascertained by cutting off a small piece of an unimportant part of the print and putting it in the solution with the print and letting it remain for 5 minutes, it is then taken out, dried between blotting paper, steeped in dilute nitric acid and laid between blotting paper again to remove the superfluous acid, it is then 150 APPLICATIONS OF PHOTOGRAPHY. placed in the fold of a sheet of printing paper and rubbed on the back India, with the thumb-nail. If it gives a good set off, the transfer is taken out of the solution, well washed with hot water till all the strontia is re¬ moved, and then laid between blotting paper for a minute or two till evenly blotted off, it is next transferred to a solution of dilute nitric acid 1 to 5, and allowed to remain from 1 to 3 minutes according to the thick¬ ness of the paper, it is then taken out of the acid, laid between blotting paper, thoroughly blotted off and transferred as described for the first process. Much more pressure is required for transferring old prints than new, it is therefore better only to use two felts while transferring and give a stronger pressure, what is called a dry proof pressure will do. The mode of charging up transfers from old prints is also different. When the plate is gummed in and charged up, the ink and gum are left upon the plate, it is fanned dry and allowed to stand for 10 or 12 hours and then washed clean, gummed in and charged up again. The charging up ink is made by taking a table-spoonful of olive oil and mixing it with thick dissolved gum arabic about the size of a hazel nut, and then adding the same quantity of strong lithographic printing ink and mixing it to the consistence of thick treacle, adding more oil or ink as the mixture is too thick or too thin. The zinc plates that have received anastatic transfers must not be wetted more than necessary during the printing, and when leaving off work the plate must be rolled in clear and sharp, gummed and dried at once and put away in a dry place. MATHEMATICAL INSTRUMENT DEPARTMENT. The Mathematical Instrument Department is the depot for all Mathematical x Instrument De- scientific instruments required for the use of the Survey Department, payment. Public Works Department and Meteorological Observatories, it also undertakes their repairs and the manufacture of a great many. It is well fitted up with suitable machinery, worked by means of a small steam engine. The staff consists of a superintendent, 2 European mathe¬ matical instrument-makers, with a large establishment of store-keepers, clerks and native artificers. REPORT ON THE CARTOGRAPHIC APPENDIX A. EXTRACT FROM THE REPORT OF MARSHAL VAILLANT TO THE ACADEMY OF SCIENCES ON GEORGE’S METHOD OF CORRECTING ENGRAVED COPPER-PLATES. ( Read at the sitting of the 7th July 1856.) “ Every one knows, but somewhat vaguely, that engraving on copper is a very slow process, and that to make corrections on an engraved plate is not only very difficult but also dangerous to the work of art to be retouched. “ It is especially in the course of the operations for the topographical map of France that these inconveniences show themselves most gravely. “ In fact, before a sheet, surveyed on a scale of 1:40,000, can be put into the hands of the artists who engrave it on the scale of 1:80,000, at least two years* preparatory labor is necessary for the compiling and drawing. The engraver's work alone requires from five to eight years, and costs from 12,000 to 20,000 francs. Thus, when the plate is finished after great expense, an interval of from seven to ten years or often more has elapsed since the last operations on the ground. “ However, the objects represented are not unchangeable as a picture, the efforts of industry, the alterations in roads, the openings of railways, the digging of canals, and administrative improvements cause continual alterations, which must be reproduced on the map, otherwise it would be out of date and useless at the moment of its publication. “ Alterations must therefore be made on the plates of the map of France at the moment of their publication, and, in the stirring times in which we live, similar changes must perforce be made from year to year, one may say even oftener. “ Until now these continual changes have only been made with re¬ luctance at long intervals, and under the pressure of an absolute neces¬ sity. Henceforth a new method wifi allow this to be done without delay, without trouble, and almost without expense. This valuable pro¬ cess is due to M. George, an engraver at the Depot de la Guerre . A few months ago there was only one way of correcting an engraved plate, i. e., by “ knocking up " and re-engraving. “ The operation called ff knocking up" is executed by means of a hammer, the repeated blows of which drive up the metal so as to fill the 152 APPLICATIONS OF PHOTOGRAPHY, hollow caused by the scraper which has removed the first work, so that fresh work may be put in. “ Without entering into further details, it is easy to understand the principal inconveniences of this method. “ The knocking up produces, without one’s being able to help it, a great number of little undulations which alter the surface. It covers up the plates and leaves them bent, causing springiness when printing, it alters the outline, even at some distance from the erased parts, and no engraver, however clever he may be, can entirely remedy it (the margins of certain sheets are no longer square) ; it gives the plates an unequal thickness, which makes the printing laborious, and hastens the destruc¬ tion of the parts which have retained their original thickness. Lastly, this very destructive action of the hammer has yet another effect of des¬ troying a great deal more of the engraving than is necessary, and to re¬ quire in consequence a long work of repetition before the corrections themselves are touched, some of the good work requiring to be done over again. “ As soon as a workshop was established at the Depot de la Guerre for reproducing the plates of the map of France by means of the galvano- plastic processes, the idea suggested itself of applying these processes to the corrections. As there exists between the original plate and the copy an intermediate plate, a sort of counterproof moulded in relief on the first, and upon which the latter is moulded in intaglio, it was simple to remove from the intermediary plate, by means of a scraper, all that was not required to be reproduced on the new sheet; in this manner, after the termination of the operation, a plane surface was obtained on this latter sheet in the place of the engraved parts required to be filled in. “ This was already an advance ; but this second method was also in¬ convenient. First; the entire reproduction of a sheet was necessary for each new correction, and the plates for a single sheet might thus be multiplied without end. Secondly ; an entire reproduction requires at least a month’s work, and costs moreover 300 francs (£12). Lastly, the operator is never entirely free from uneasiness, so serious would be the consequence of an accident which, by causing the adherence of the sur¬ faces, would involve the immediate loss of a plate representing an expense of 20,000 francs (£800) and twelve years of labor. “ In presence of these difficulties, M. George conceived the happy idea of making the corrections without an intermediary, by depositing metal in the engraved lines, and of taking advantage of the adherence so dreaded in an entire reproduction, and thus to reduce the circle of 153 u REPORT ON THE CARTOGRAPHIC operations to all that was strictly necessary in space, in time, and in cost. “ By his method, the corrections are limited to the faulty space, the false lines are filled up by metal applied without blows, without vio¬ lence, without general alteration of the plate, and perfectly adherent. There is no necessity for going over again with the graver that which was good at first. The time and the expense are reduced to a minimum, and corrections of all sorts, in all styles of engraving, will henceforth be as sure as they are easy. “ M. George has thus rendered not only a great service to the Bepdt de la Guerre and to Topography, but also to the art of engraving in metals in whatever manner it may be applied.” 154 APPLICATIONS OF PHOTOGRAPHY. APPENDIX B. EXTRACT FROM “ A MEMORANDUM ON THE APPLICATION OF PHOTO- GRAPHY TO SURVEYING,’* BY M. LAUSSEDAT, BATTALION CHIEF OF ENGINEERS, published in No. 17 of the “ Memorial de POfficier du Genie.” The want of success of the efforts made to introduce picturesque views as essential or auxiliary elements in surveys, and especially in reconaissances, has always appeared to be caused by the difficulty of accurately drawing a landscape. For this reason in 1854 we proposed the use of the camera lucida as the most simple and convenient instru¬ ment to guide the hand of engineers. We had already, at that time, and even before, thought of using photographic views, which entirely dispense with hand drawing, but the processes then known were too delicate and too uncertain, so before advising their use we waited till they had become simple and in current use. The improvements which seemed most desirable had, happily, not to be waited for very long; consequently, for some years past, the army has counted among its members several clever operators, whose number is continually increasing. In this respect then, there are no longer any serious difficulties to encounter, and the question is reduced to calling the attention of our photographers to a military application, the interest of which cannot escape them. I.—DEFINITIONS AND GENERAL PRINCIPLES. The landscape views which are depicted at the back of a camera Definitions and general princi- obscura are conical perspectives on plane surfaces, such as they are defined P les * in geometry, and, consequently, possessing the same properties as these last. According to the theory of lenses, the optical centre of the objective of the apparatus is nothing else than the apex of the conical perspective, or what is commonly called the point of sight. The foot of the perpen¬ dicular, dropped from this point on to the plane of the picture, is called the principal point. When the picture is vertical, which condition we suppose always to be fulfilled, the horizontal line of the perspective, that is to say, the line by which the horizontal plane passing through the point of sight cuts the picture is a horizontal^ straight line passing through the principal point. 155 REPORT OX THE CARTOGRAPHIC As we shall only have to operate on landscapes composed of objects which, as a rule, are sufficiently distant from the apparatus, that their images may all be formed in the same focal plane (principal focal plane) f the distance from the point of sight to the picture will remain unchanged. This distance is an important element, because it determines the length of that part of the visual rays comprised between the point of sight and the picture, that is, the lengths of the lines of sight. Fig. 1, Plate XI will illustrate the foregoing,-—Let 0 be the optical centre of the objective, jOP its optical axis, supposed to be horizontal, and focal plane occupied by a ground glass on which the image is clearly depicted. At the distance OP, equal to qj and taken in front of the objective, towards the natural landscape, let us conceive a plane and transparent surface QRST parallel to the focal plane. It is clear that the perspective which would be seen depicted on this surface, by placing the eye at 0 , is identical with that which is projected on the ground glass QUSP, and if a horizontal plane is conducted through the point 0, the traces IIPN and of this plane, on the direct perspective, as well as on the ground glass, will indicate the points of the natural landscape which are at the same level as the point 0. Returning to the preceding definitions : The optical centre 0 , of the objective is the point of sight of the perspective QRST, traced upon a vertical picture plane interposed between this point of sight and the natural landscape. This perspective may be superimposed upon that which is projected on the ground glass viewed by transmitted light, the distance OP from the point of sight to the picture being equal to the focal distance Od > the principal point, and HPN is the horizontal line on the direct perspective, j and HdSI are the principal point and the horizontal line on the ground glass. In short, the aerial image seen on the ground glass is precisely that which is obtained photographically under the name of positive proof, and the positive proof itself may be substituted for the ideal image of the transparent surface QRST. To recapitulate, it is clearly proved that photographic views repre¬ sent geometrical perspectives of the ground, with the optical centre of the lens for point of sight, and upon a picture plane the distance of which from this point is equal to the principal focal length of the objective. Let us consider then a photographed view, transferred to QRST at the distance OP in front of the point of sight, that is to say, on the same side as the natural landscape. 156 IPkAWH ZS. &AW3SJgJB>AOT3 S’S'STCIgSE. Fig. 2 APPLICATIONS OF PHOTOGRAPHY, The visual rays 0 A, 0 B, 0 C, 0 D which end at the points A, B, Cj I) of the ground, meet the picture or the sight in a , b y c , d, and the projections 0 A', 0 B ', 0 C , 0 Bf of these rays on the plane of the horizon, will meet this same picture in points a ’, b', c', d’ , which will be the feet of the perpendiculars dropped from the points a 3 b, c, d } on the horizontal line IIP JV. The straight lines 0 a !, 0 V, 0 c, 0 d', drawn from the point of sight 0 to the feet of these perpendiculars being all situated in the plane of the horizon, will form between themselves angles which will be those of the corresponding visual rays, reduced to the horizon ; again, the angles a 0 a!, bO b', c 0 c', d 0 d' } formed by each of the visual rays with its projection, are nothing else than the inclinations of these rays to the horizon. Upon a photographic view Q R S T (fig 2. plate XI), being given, the position of the principal point P, and the horizontal line II P N } and knowing besides the focal length of the lens which has been used for tak¬ ing the view, that is to say, the distance 0 P from the point of sight to the picture, we may obtain, directly reduced to the horizon, the angles comprised between the different points of the landscape, and determine graphically, or by their trigonometrical tangents, the heights or the de¬ pressions of each of these points. To do this, we have only to turn down the plane of the horizon on that of the picture, around the horizontal line H P N taken as an axis. The point of sight will find itself turned down in 0 on P 0 perpendicular to the horizontal line HPN, and at a distance 0 P from this line, equal to the given focal length. Then by letting fall from the different points a , b, c 3 d 3 the perpendiculars a a ', b b' 3 c c’, d d ', on to the line IIP N } and joiningthe ends a' 3 b ', c, d' 3 of these perpendiculars, to the point 0, a'O b' a 0 d, dO d’, will be the angles reduced to the horizon, which would have been found by means of a plane table or divided circle stationed at the same point as the camera, by aiming successively on the points of the field of which a, b } c } d are the images. As for the apparent angular height of any one of these points, for example that of the top a of a tree, it will be obtained graphically by raising at d on 0 a the perpendicular d a", equal to ad , and by joining the point a" to the point 0 . It is clear, in fact, that the angle d Oa" is equal to the required angle aO d of the space. But this construction may be avoided by using instead of the angle itself, the proportion ^ which is its trigonometrical tangent. 157 REPORT ON THE CARTOGRAPHIC Construction of the plans by means of per¬ spectives. Planimetry. Measuring of Angles. Arrangement of the views for the construction of the plan. II.—CONSTRUCTION OF THE PLANS BY MEANS OF PERSPECTIVES. The method which naturally presents itself for constructing a plan by means of several perspectives, taken from different points of view, is that which is known in topography as the method of intersections. In fact, on a little reflection, it will be seen that the successive stations of a plane table survey, or even the apices of a triangulation are really points of sight from which the observer discovers the ground under different aspects. It is equally clear that the angular measurements, taken from these points of sight, by operating direct on nature, are precisely the same as those which may be deduced from perspective views drawn or photographed. 'Planimetry. In order to construct the plan, a suitable base must be measured in the ordinary way, with measuring rods, a chain, the stadia, or even simply by pacing, according to the importance of the survey and the degree of accuracy desired. When the length of the base is not too great the most convenient method is that of the stadia. Measuring of Angles. —In ordinary triangulations, the angles included between the directions of the different sides are measured by means of a divided circle. It is also necessary for us to measure directly some angles, and for this purpose we use a circle carried on the instrument. Arrangement of the views for the construction of the plan. —Return¬ ing to the photographed views, let ah (fig 3 plate XI) be the measured base reduced to any convenient scale, hac and ahc the angles measured from the stations A and B, represented in a and h , between the direction of the base and the directions ac , he of the same point of the ground, which will thus be found determined in c. Suppose also a proof No. 1, taken from the point A , and a proof No. 2, taken from the point B , on which the point c, under consideration, is found represented, in the one in c i, and in the other in c 2 let us suppose the point of sight of the proof No. 1 turned down round the horizontal line h % n l} and transferred to a , and that of the proof No. 2 turned down round h 2 n z , and trans¬ ferred to h, join each of these points of sight respectively to the projections d and c", of the images c l and c 2J then let us turn the proof No. 1, and the line ac' round the point a , until this line passes through the point c previously obtained, and the proof No. 2 round the point h until the line he" passes through the same point, the two proofs are then in their proper position relatively to the base, and it will be easy to fix on the plan, all the points whose images are to be found on both these two proofs. 158 APPLICATIONS OF PHOTOGRAPHY. In fact if d l3 and d 2 , be the images of a certain point of the ground on both perspectives/ it is clear that by joining the point a with the point d', the projection of the point d l3 and the point b with d" the projection of d 23 the intersection d of the two lines ad' 3 bd" will fix the position of the point in question on the plan. In the same way the points e 3 f may be obtained. Thus, the direct measurement of the base AB and the two angles BAG, ABC suffice to fix a great number of points of the plan by means of photographic views taken from the stations A and B, and consequently by joining those of these points which belong to the same objects, the real horizontal dimensions of these objects may be represented, at any rate in part. Levelling.— The vertical distance from each of the points thus Levelling, obtained to the horizontal plane of one or other of the stations A and B is easily determined. Let us consider for example, the point d, and find out its vertical distance from the horizontal plane of the station a. The length aa' of the perpendicular let fall from the image d L upon the horizontal line h^ n l is the apparent linear height of the point d, at the distance ad'. The true height required x of this same point will then be given b}^ the proportion x = ad X ^ the true distance ad of the point in question from station a being measured on the plan according to the scale. Note .—This true height is not the difference of level between the point d and the station a, hut that between this point d and the optical centre of the lens at this station. Con¬ sequently, to obtain the difference of level with the actual ground of the station, the height of the instrument, which must always be carefully noted for this purpose, must he added. Verification of the planimetry.— -The verification of the points verification of . ill n n 1 i the planimetry. obtained on the plan, by means ot two proofs, may be made with a third proof which contains the same points, just as is always done in ordinary surveying when using the method of intersections. It should also be remarked, that in this case when the exactness of part of the plan constructed by means of two proofs has been ascer¬ tained, all the other proofs, which contain the images of any of the points already obtained, may, in emergency, be arranged on the plan without any necessity for making fresh direct measurements. However, it will always be better to know the distances between the successive stations, and to observe from each of them, the angle or the angles which are actually necessary for the arrangement of the points. Verification of the levelling. —When the horizontal or inclined dis- verification^ of tance of the two stations a and b has been measured, and the inclination of the visual ray which unites them, the difference of level of the two 159 REPORT ON THE CARTOGRAPHIC stations may be deduced, as is well known. Now the levelling of the different points of the plan which are found represented both on print No. 1 and print No. % may be referred either to station a or h, which will give a verification, in case of need, for each of the points required. III.—THE PHOTOGRAPHIC APPARATUS EMPLOYED. The Photo¬ graphic appara¬ tus employed. The apparatus used for taking the photographic views is exactly the same as that in ordinary use, but to render it fit to be used for surveying, a fixed horizontal graduated circle, of which the divisions are traversed by a movable index arm, is fitted to the camera at the base of its vertical axis. The movable arm carries a clamp at one end which serves to fix the instrument in any required direction ; it also carries a tangent screw to facilitate the laying, and a vernier reading to one minute. The angles at which the optical axis of the lens is turned are thus measured with sufficient precision. The instrument comprises also a spirit level and telescope fitted against one of the sides of the box. The telescope, placed in collars, is moveable round a horizontal axis, and carries with it an index, the verniers of which traverse vertical arcs; the telescope is maintained in position by a clamping screw, and a tangent screw enables it to be pointed exactly. The reading of the verniers gives, if necessary, the inclination of the optical axis of the telescope to the horizon. Over the telescope there is a moveable spirit level so arranged that it may be turned end for end when required or fixed securely when travelling. The plate carrying the horizontal axis, and in which the graduated vertical arcs are cut, is firmly fixed to one side of the camera, a counter¬ poise being fixed to the other side to preserve equilibrium. Besides the ordinary simple cross-wires, the telescope is furnished with two other parallel wires which serve for the direct measurement of distances by means of the stadia. Finally, four very fine needles are fixed inside the camera in the middle of the four sides, just in front of the groove containing the dark slide. These needles intercept the light, and mark four index points on the plate, which being joined in pairs give the position of the horizontal line and of a perpendicular passing through the middle of it. These needles may be adjusted by means of adjusting screws, when necessary. Besides this, the instrument is so constructed that— —When the telescope is horizontal, its optical axis is at the same height as that of the lens, and when moving round the vertical axis, these axes describe the horizontal plane. 160 APPLICATIONS OF PHOTOGRAPHY. 2 nd. The groove at the hack of the camera is so construct¬ ed that the plane of the proof shall be vertical and perpendicular to the optical axis. 3rd. The index needles, especially those showing the horizontal line, must be very exactly fixed. As in many cases the horizontal line will not be exactly in the middle of the picture but above or below it, the front carrying the lens is fitted into grooves the sides of which are graduated with a scale, the zero of which corresponds to the position of the axis of the lens in which the horizontal line passes through the needles; it is therefore only neces¬ sary to mark the distance to which the lens has been moved up or down, and when the lens is raised a certain distance, the horizontal line must be marked on the proof at the same distance under the line marked by the needles or vice versd. Determination of the distance of the point of sight from the picture .— This distance which regulates the length of the lines of sight and consequently that of the lines of construction, must be determined with the greatest possible accuracy. It is calculated indirectly by measuring— first , the linear distance from the principal point of sight to another point situated on the horizontal line, either on the ground glass or on a positive print; and, secondly , by measuring with the azimuthal circle the angle comprised between these same two points of the natural landscape. Returning for example, to fig. 2, upon which the point 0 represents the point of sight turned down upon the picture plane. By joining any point h' on the horizontal line with the point of sight, we form a triangle with a right angle at P, which will be solved when the side Pb' of the right angle and the acute angle at 0 are known; now, these two quantities are those we have just mentioned, and which may easily be measured to within one minute of the angle and a fraction of a millimetre in the side. The required distance from the point of sight to the picture, or the side OP, is then calculated by the formula. OP = Pb' cot POP. This distance is the focal length of the lens. IV.— ERRORS TO BE FEARED IN THE APPLICATION OF PHOTOGRAPHY TO SURVEYING. The errors to be feared in the employment of photographic views to construct plans are of two kinds, viz., those which are inherent to the 161 w REPORT ON THE CARTOGRAPHIC 1. Errors from distortion of im¬ ages by the lens. 2. Degree of precision of the graphic opera¬ tions. very nature of the instrument, and those which are common to all purel v graphic operations. 1 .—Errors arising from distortion of the images by the lens. Note .—The principal of these errors is the angular distortion at the edges of the picture caused by spherical aberration, but with the improved lenses, lately introduced by Dallmeyer, Ross, and others, the spherical aberration is entirely absent, or so much reduced, that in practice such errors may be disregarded, since with a single achromatic meniscus,—a form which gives more distortion than any other,—the error has been found to be not more than 4° in the complete horizontal circuit. It is therefore unnecessary to introduce here the elaborate mathematical calculations by which M. Laussedat has discovered the amount of error, and the means of rectifying it. 2 .—Degree of 'precision of the graphic operations . The positive proofs from which the constructions are to be made must be perfectly sharp and clear. They are stretched on a sheet of thin Bristol board and are fastened to it round the edges alone. The focal length of the lens must be determined upon a similar proof in order to avoid having to allow for the alternate effects of extension and contraction which the paper of the proofs undergoes during the manipulations. The horizontal line and prime vertical are then drawn distinctly in red, and the most conspicuous objects are numbered in red; perpendiculars are drawn from them on to the horizontal line and on to the prime vertical. In this manner the different points of the view are reduced to a system of three coordinates very easy to measure or read, viz., the distance of the point from the prime vertical, its distance from the horizontal line, and the length of its line of sight reduced to the horizon. Instead of arranging the proofs on the drawing, which would be inconvenient in many ways, among others by requiring a very extensive space, it is only necessary to trace the horizontal lines and the perpendi¬ culars let fall on these lines from the corresponding points of sight. On these horizontal lines the projections of the images of conspicu¬ ous objects are marked off from slips of paper which correspond exactly with the projections of the images on the horizontal lines of the proofs; the points so marked off are then joined with the corresponding points of sight. Exactness which may be attained in the planimetry .—The graphic errors which may be made in the construction of the plan will, as a rule, diminish as the lines of sight are longer. Now, the distance of the points of sight from the picture is the smallest of these lines of sight, and for this reason the preference should be given to lenses, of long focus besides 162 APPLICATIONS OP PHOTOGRAPHY. which, large proofs include much more detail than small ones under otherwise equal conditions. When only determining on the plan the points situated within the horizontal lines of each proof, that is to say, the points situated between these lines and the corresponding points of sight, the graphical errors may be considered as nil . There are also two not less important elements to take into account when considering the greatest distance at which one should operate; these are the scale of the plan and the focal length of the lens. Thus, if a plan is constructed on a scale of 2 no o w ^h y i ews taken by a lens of 18" focus, this length of 18" representing a real distance of 1000 yards on the scale, as a rule those points only which are within 1000 yards will be determined with accuracy, and for a plan on the scale of jIqq this limit would be extended to 2,500 yards. In all cases the ordinary rules of topography must be observed. Accuracy of the levelling .—The accuracy required in the levelling is much greater than that with which one may be satisfied in the planime¬ try, thus, an error of *018 in the position of a point on a plan at the scale of 2 J 00 no g rea k consequence, but the same error in the height of an object would make a difference of one yard. To perform the levelling, the distance of the required point of the proof from the horizontal line, and the length of the line of sight in hori¬ zontal projection, which is obtained by inspection, are entered in a table, and the difference of level between the object and the station is found by the following formula. x — md X ~y where f is the length of the line of sight ad' (fig 3, Plate XI) d is the linear distance ad measured on the plan from the point in question to the station, and h is the vertical distance d'd of the image of this point from the horizontal line, measured on the proof; the scale of the plan be- in 2 b The accuracy of the levelling is thus proportioned to the magnitude both of the scale of the plan and of the focal distance. Further, the levelling becomes less exact as the points are more distant from the station. In practice it has been found that on a plan to the scale of 20 W constructed by means of views taken with a lens of 18" focus, the levelling of points situated about 500 yards from the stations was exact to within about 1 yard. For nearer objects the error was usually only a few inches. 163 REPORT ON THE CARTOGRAPHIC 3. Accidental Errors. 3 .—Accidental Errors. One of the great advantages of the photographic over the ordinary methods of surveying is, that the prints show the exact appearance of the object on the ground and there is usually no difficulty in recognizing the same object on the views taken from different stations. In ordinary surveying the surveyor frequently forgets the arrange- ment of his objects and if he suspects any error in his notes, he must go back to the field, but with photography there is no necessity for this, the draughtsman has the pictures of the ground always under his eyes, and can consult them at any time in order to control or rectify his operations. Accidental errors must therefore be very rare, and they are always easy to correct. We may lastly remark that the views combined with the plan form a valuable supplement to it, without which one may commit errors of appreciation which are also important. The conventional signs used in topography really give no idea of the relief of most of the objects above the surface of the ground, and as for the ground itself, one can scarcely ever realize its form, even when delineated by horizontal contours, without a study which the simple inspection of picturesque views would greatly facilitate. For this reason the utility of collections of photographic views would be especially appre¬ ciated in mountainous countries. Finally, when the method of photographic perspectives is employed one need only fear the accidental errors which may be committed in reading angles, or in the direct measurement of the distances serving as bases for the operations, and it is very evident that the views themselves, by facilitating the appreciation of the ground, will often enable these errors to be rectified and prevent a number of others. V.—SUM OF THE OPERATIONS OF A SURVEY. The necessary operations for executing a complete survey, by the method of perspectives obtained by the aid of photography, may be classed under four principal heads, viz . :— 1.—The geometrical operations, comprising the measurement of the distances between the successive stations and of the angles which assist the arrangement of the views for the construction of the plan. 2 .—The photographic operations. 164 APPLICATIONS OF PHOTOGRAPHY. 3. —The execution of sketches of detail made by eye on the ground in the quickest possible manner. 4. —The graphic constructions and fair drawing of the plan, for which all the information gained on the ground is used. Geometrical operations.—Choice of Stations.— Independently of a base of convenient length, which must indispensably be measured when great exactness is required, it is better to survey the stations one after another by traversing , which gives a broken or polygonal line of which each part is itself a base for the operations carried on at its two extre¬ mities. The distances may be measured with a chain or stadia, and the angles with the horizontal circle on the apparatus. The choice of sta¬ tions is guided much on the same principles as in ordinary surveying, but they should always be chosen on the most elevated positions and at tolerably long intervals. The most advantageous stations are those which are situated so high that one may see the nearest objects, which, at a lower point of sight, would be covered one by the other. Photographic operations.—Any of the ordinary photographic pro¬ cesses may be used, but the dry collodion process appears the most suitable* as though the plates require longer exposure they can be developed at leisure, and a large number of prepared plates may be taken into the field ready for use, packed each in a light cardboard dark slide without any great,increase in weight or bulk. Sketches of detail. —Notwithstanding the large number of indications they contain, the photographic views always leave more or less exten¬ sive gaps. The undulations of the ground, or prominent objects, frequent¬ ly interrupt the continuity of the lines in such a manner that to obtain all the details it would be necessary to multiply the stations beyond measure, and thus the method would lose its essential character of simplicity. It must therefore not be supposed that photography entirely dis¬ penses with surveys of the details, but these may be executed much more rapidly than in the ordinary manner, and only bear upon the less apparent parts of the ground without causing fear of serious errors, because there are always sufficient elements for correction in the indications furnished by the perspectives. Some simple sketches drawn by eye and pacing, principally through groups of habitations, in the depressions of the ground and in land covered with vegetation, and some altitudes calcu¬ lated with the aid of a reflecting level, will generally suffice to fill up the gaps and correct the errors of construction which may accidentally be 165 REPORT ON THE CARTOGRAPHIC made by taking- one object for another in places where tlie perspectives are too full of detail. There exists,, moreover, between the dimensions of the instrument, the scale of the plan, and the degree of finish required for the representa¬ tion of details, a harmony of which an exact idea can only be obtained by a little practice, and after having attentively examined topographical plans on different scales. This examination teaches, for instance, that the use of the views obtained with the apparatus we have described is especially advantageous in surveys on a large scale, such as those compris¬ ed between and io * 0 - 6 , or 31° 6 in.—1 mile to 6*3 in.=l mile. Graphic constructions.—Fair drawing of the plan.—^he tracing of the polygonal canvas and the index lines of the different views, the angles formed by which with the sides of this canvas have been entered in the field book, is performed as in surveys with the compass, with a protractor of tolerably large radius or better by using tables of chords. On all these index lines a constant length equal to the distance from the point of sight to the picture is laid off from the corresponding station, and at each of the ends thus obtained a line is drawn at right angles to them. These perpendiculars are the traces of the picture planes of the different views. When all the information they contain has been taken from the perspectives, the plan is finished by inserting the details surveyed separately. It is as well that this should be done by the person who surveyed the details, or at any rate with his assistance; but if the field book of the survey of the polygonal canvas has been well kept, the other operations may, however, be confided to any practised draughtsman, even though he has not been out in the field. Conclusion. In presenting the method of plane perspectives as the best to employ when it is desired to apply photography to the study of ground, we have not sought to exaggerate the advantages of this method or to hide its incompleteness. It would be scarcely reasonable, in fact, to hope to discover on as perfectly detailed views as can be imagined, that which cannot be seen on the ground without going over it in every direction. Therefore, it is not, in truth, the method itself which must be blamed, if there are gaps to fill up in the plan which it helps to con¬ struct, because it would necessarily be the same with every other process founded on the employment of photography, and we do not hesitate to state that no process of all those which have hitherto been proposed unites in the same degree the two essential conditions of simplicity and accuracy. 166 APPLICATIONS OF PHOTOGRAPHY APPENDIX C. ORDERS FOR THE CONDUCT OF THE BELGIAN SURVEY. I.—EXTRACT FROM THE INSTRUCTIONS FOR THE OFFICERS OF THE BELGIAN SURVEY DEPARTMENT, CHARGED WITH TOPOGRAPHICAL OPERATIONS ON THE GROUND IN 1860. 1. —Before his departure each officer will receive a plane table upon which the planimetry of the ground to be levelled has been drawn to a scale of 1:20,000. 2. —Independently of the plane table, a tracing on tracing cloth of the planimetry of the ground to be surveyed will be made over to him, this tracing is intended for surveying the details of the ground, and is divided into 6 parts, in order that each of them may be placed in a little portfolio with which each officer is to be provided. 3. -—The polygons, traverses, and profiles, levelled on the ground, and also the contours, are to be drawn in pencil on the plane table. 4—'The details will be surveyed in pencil, they are to be put in with ink in office the same day, after the work on the ground. 5.—(Has local reference only). 6 .—In surveying the details, particular attention is to be paid to filling up the gaps which exist on the cadastral maps and the changes which have taken place; in this respect the points to which attention is particularly drawn are—the water courses, communications of all kinds, houses and gardens, chapels, crosses, and isolated trees, finger posts, viaducts, aqueducts, bridges, wells, mile-stones, barriers, springs, weirs and dams, in fact all the objects mentioned in the tables of colors and conventional signs. The orthography of the names is to be scrupulously observed, and in case of necessity, recourse must be had to local authorities. 7. —In each parish, the cadastral records are to be consulted in order to take down all the named places on the ground as well as the names of the roads; this information is to be shown on the tracings. Wet days are to be spent in such researches. 8. —The new routes, canals and railways, which are not put down on the plane table, are to be surveyed on the ground; for this purpose 167 REPORT ON THE CARTOGRAPHIC the officers will apply to the engineers and overseers of bridges and roads to obtain the tracings of these lines. 9, 10, 11.— (Have only local reference). 12. —The declination of the compass for each parish is to be regis¬ tered in the levelling registers, in the column of “ observations.” The results of this operation are to be sent to the Chief of the Topo¬ graphical party. 13. —Officers engaged in topographical operations are to bear in mind that the excellence of the configuration of the ground does not result only from a great number of altitudes, but more from the choice of the position of these points. To attain this, they will direct the peri¬ meters of the circuits, traverses, and profiles of the levelling as much as possible along the heights and thalwegs ; they will follow the lines of greatest slope, and will take points on the summits, and spurs, at the sources and confluences of streams, at the intersection of roads, at the outlets of valleys, and on the lines of intersection of the different accidents or undulations of the ground. The following features of a height are to be distinguished, its foot, its side which forms the slope, the brow or ridge which rises above the side, and the summit or crest; altitudes are to be taken at the foot of the slope, at the intersection of the slope with the ridge and the length of the crest; the point where the contours turn back must be carefully determined. Finally altitudes are to be taken at the points enumerated in para. 6. 14. —A series of levels will be run along each highway, the point of which the altitudes are to be taken in this levelling are to be chosen in such a manner as to indicate the different undulations of the road. 15. —Altitudes are also to betaken at the tops of precipices or steep descents, the height of these accidents of the ground will be deduced by means of the chain. 16. —The polygons of levelling are to have a mean surface of 600 hectares, (2*319 square miles). The maximum error must not exceed 0 m, 25, or about 10 inches. 17. —While the crops are on the ground, the levelling will be conducted by directing the perimeters of the polygons as well as the traverses, along the roads, lanes, and footpaths. Benchmarks will be made on the ground in order that the levelling may be completed after the harvest. 18. —The contours will be traced on the ground. This operation will always be performed in presence of the Head of the Party (Chef de Brigade). 168 APPLICATIONS OF PHOTOGRAPHY. 19. —The differences between the different points of the polygons, traverses, and profiles, should be laid down by means of measurements with a pair of compasses taken on the scale, and not on the double decimetre. 20. —The number of points should vary with the nature of the ground, and should be more numerous in proportion to its unevenness. 21. —Officers will arrange between themselves for the levelling of the ground contiguous to the common margin of two plane tables. The Officer who shall have first levelled a part of this ground, will send a copy of his work to the one to whom the neighbouring plane table is entrusted. This levelling will be accompanied by a sketch showing the situa¬ tions of the levelled points and the tracks of the contours. This part of the work will be conducted with the greatest possible care, in order to facilitate the joining of the plane table sheets one with the other. This joining will be done at the Depot de la Guerre. 22. —It is desirable that an altitude should be determined at the church of each parish, consequently an altitude will be taken by means of the compass on the doorstep of those churches which do not posseses a base benchmark. This operation will be performed with the greatest exactness. A sketch of the front of the church, with the position of the level¬ ling staff, will be drawn in the column “ observations” of the levelling register. The instructions in this paragraph are to be strictly carried out for bridges, watermills, dams, weirs, and sluices. 23. —Officers will take care to practise all the means of verification employed in topography, especially that which consists in frequently tak¬ ing bearings of remarkable points on the ground, such as steeples and trigonometrical signals. This operation will have the further advantage of verifying the declination of the compass, and guiding the officer when he comes to plot the work executed on the ground. 24. —By taking bearings on the cross, which is at the top of spires of towers, or a well fixed point at the top of these buildings, their height may be determined. To obtain this result, the angle given on the scale of the levelling compass and the distance will be taken on the planimetry by means of a measurement with a pair of compasses. 169 x REPORT ON THE CARTOGRAPHIC 25. —The levelling registers are to be kept up daily. In the column (( observations” care will be taken to enter all the information necessary for determining the points mentioned in paras. 6 and 12. 26. —In the column headed “primitive altitudes” (Cotes primitives) will be noted the altitudes as they have been levelled; in the column headed “ corrected altitudes” the corrected altitudes of the ground will be entered, the latter will be written on the plane table minutes to proceed with the tracing of the contours. 27. —The operations for obtaining the error of collimation are en¬ tered in the levelling register. The Heads of Parties will check these registers each time they visit their Officers. 28. -— 1 The trace of the levelling will be kept up regularly, the polygous being entered in red ink, the traverses in blue. The base altitudes will be written in Indian ink, and included in parentheses. 29. —Officers are responsible for the instruments entrusted to them. Every instrument damaged by neglect or carelessness will be re¬ paired at the cost of the Officer to whom it was entrusted. On the return from the field they will submit to the officer in charge of the instrument store a memorandum on the repairs required and on the alterations to be made. 30. —Experience having shown that an average of 55 hectares (136 acres) may be levelled daily, including bad weather and Sundays, Officers will strive to turn out that amount of work. 31. —(Is of local interest only). 32. —Officers will enter daily in a register the observations they may be able to make on the physical constitution of the ground, as well as the statistical, historical, and military documents they may be able to obtain. By thus proceeding they will obtain the materials necessary for the compilation of the report which should accompany their topographical operations. 33. —By help of the statistical tables, produced by parishes, Officers will give an estimate for the number of billets for the different arms that could be provided in the parishes comprised within the bounds of their plane table. This register of notes will be kept up and the Heads of Parties will check it whenever they go upon the ground. 170 APPLICATIONS OF PHOTOGRAPHY, 34. —In winter Officers will occupy themselves with the fair drawing of their work, which should be finished, including the report, by the 1st March. During the month of March they will draw the plane table sheets which are to be levelled during the next field season. In order that officers may be able to send in their work by the 1st March, they are strongly advised to avail themselves of bad weather to draw the details on parts already levelled. 35. —Officers will take the declination of the compass by availing themselves of the straight lines which divide the plane table in squares. To do this they will choose two points well de¬ termined on the plane ta¬ ble, one of which should be accessible. Let A be the position of a steeple or trigonome¬ trical point (see the accom¬ panying figure), a the cor¬ ner of the division of a plot (d’une division de parcelle) well marked on the plan. The instrument is placed in station at a 3 and directed towards A, the graduation marked at the extremity of the needle is read, suppose it to be 370° 75', the angle given by the plan is then taken by means of a protractor and the rectangular lines, suppose it to be the angle m o ^=343° 70', then the declination of the compass will be 370° 75'— 343° 70'=27° 05'. If the point A is accessible, the compass will be set up at A and directed on a , and the operation will be continued as described for a. The mean of these two angles will then be taken; this mean, diminished by the angle taken on the plane table, will ’ be the declination for the direction a A. The same operations will be performed for the directions b A and c A, the mean of these three results being the declination finally adopted. The limb of the compass will then be moved by an amount equal to the difference of these two readings in such a manner that when the compass is set up at the stations a } b , and c and the telescope is again directed on A, the needle should mark the angle given by the protractor. 171 REPORT ON THE CARTOGRAPHIC Supposing that the nature of the ground will not permit two well- defined points to be used, the declination may be taken by means of a straight road. Two reciprocal observations will be taken as before described, and the means of the angles given will be compared with the reading given on the plan by the protractor. 36. The declination of the compass will be observed at each time of passing from one parish into another contiguous one. It must be well understood that for each observation for declination points must be used which are all in the territory of the parish in which operations are being carried on. 37. In this operation care must be taken not to set up the instru¬ ment near railways, or objects which may affect the magnetic needle. The chain used for measuring the distances must be kept as far as possible from the instrument. 38. Every Friday Officers will send in to the Director of the Topographical operations, a report in conformity with the model furnished to them. This report will be accompanied by a sketch, showing by means of tints the degree of progress of the work. The conventional colors are— 1. *—Yellow for polygons of which the perimeter has been levelled. 2. —I31ue for the levelling of traverses. 3. -*Green for the parts quite finished. Only the levelling already plotted on the plan is to be shown in the sketches. T. HENRIONET, Captain of the Staff\ Director of the Topographical Operations. II.—INSTRUCTIONS FOR THE HEADS OF PARTIES OF THE TOPOGRAPHI¬ CAL DEPARTMENT, BELGIAN SURVEY. 1. The Heads of Parties (“ Chefs de Brigade”) will keep a constant superintendence over the Officers under their orders. 2. They will maintain order and discipline among them, and will see that all instructions given to Officers are scrupulously carried out. They will constantly inspect the different parts of the work and check them often upon the ground, in order to assure themselves of their correctness. 172 APPLICATIONS OF PHOTOGRAPHY. They will be responsible for the conduct and work of the officers. All work will be signed by them in the following manner :— Seen and checked on the ground. ___ Head of the Party. 3. Before starting for the field, they will give the officers under their orders, the joinings of the plane table sheets contiguous to those already executed. 4. They will ascertain that the instruments entrusted to the officers are in good condition. They will cause them to be replaced as often as they think necessary. 5. Chiefs will inspect their parties at least once a month. Further they will assist in the tracing of the contours on the ground. They will assist with their advice and experience officers who are out for the first time; they will accompany them on the ground during the con¬ tinuance of the levelling of the perimeter of their first polygon and the two first traverses; they will watch that the calculations are made with regularity, and will aid them in this last operation. They will visit more frequently those officers who require a special superintendence. 6. The Heads of Parties should examine, during their tour of in¬ spection, all parts of the service ; they will ascertain if the details have been well surveyed and expressed on the sketches in conformity with the specimen of conventional signs and colors ; and if the levelling plotted on the sheet of tracing cloth is up to date, if the registers are well kept up; if the statistical states of the parishes are filled correctly, and if the officer has added to them his observations on the parts connected with military operations. If the officers have entered, each day in the note book, the observa¬ tions which they have been able to make on the physical constitution of the ground, as well as the historical and military documents they should try to obtain; they will take care that these memoranda are well under¬ stood, and should strive to point out to them those to which most atten¬ tion is to be paid, in order to serve as a basis for the military remarks they will have to give on the ground surveyed. 7. They will ascertain that the joinings between the edges of contiguous plane table sheets are made with care, and will mention this verification in their monthly report. This verification will also be entered in the working journal of the officer. 173 REPORT ON THE CARTOGRAPHIC 8. At each monthly inspection the Head of the Party, after having rigorously checked the finished polygons, will sign the levelling register, the working journal, and the note book. This signature will be placed, as said above, at the end of the enter¬ ing of the levelling of each polygon in the levelling books; at the end of the month in the journal of work, and at the end of the notes entered in the register of memoranda for the compilation of the report. 9. The Heads of Parties will send in every month a report to the Chief of the Topographical Department. They will mention in this report the results of their monthly inspections; they will point out the parts of the ground which have been checked and the observations they have been able to make on the ground. They will enter in their report the faulty parts of the work and the true cause of the errors. This report should reach the Chief of the Department between the 1st and 3rd of each month. 10. When the Head of a Party has signed any work, he will be personally responsible for any incorrectness which may be found in it. 11. The Heads of Parties will keep a note book in which they will enter the observations they may be able to make on the progress of the work, and the improvements which might be made in it. 1£. They will correspond directly with the officers under their orders. They will receive every Saturday the weekly reports of these officers and will forward them at once to the head of the Department. They will sign in their covering letter any observations they may consider it useful to make on these reports. On arriving on the ground the Heads of Parties will study it from a military point of view, and will point out how the ground suits the general system of the defence and organisation of the kingdom. They will apply to this ground the most probable hypotheses for the offensive operations of invading armies coming from different directions, and also for the general and local defence. They will study the remarkable military events at different epochs, and of which the ground surveyed may have been the theatre, such as battles, fights, sieges, &c., and will compare the actual configuration of the ground with that which it had at the time of these different fights. The instruction of 1844 on this subject is as follows * " Woods existed at that time which probably have been removed; enquiries will be made as to their position, their extent, outline and 174 APPLICATIONS OF PHOTOGRAPHY. nature. Attempts should be made to discover the changes that have taken place in the communications; what were the roads, lanes, paths, and watercourses at the time ? have these last not been turned off ? and, if so, what were their thalwegs ? what was the nature of their banks ? The position of bridges, fords, reservoirs, if any existed; those of ponds, marshes, and marshy meadows. Information will be collected on the surface which the villages and hamlets occupied, on the agglomera¬ tion of the houses ; on the position of the isolated buildings, such as farms and mills. In the first tour of inspection the Heads of Parties will trace out for each officer under their orders a special programme of military considerations based upon the hypotheses above mentioned, and which should be treated of in the report." In the following tours they will ascertain that this part of the work progresses. In their monthly reports the Heads of Parties will have a special paragraph on the execution of the part relating to the report. After the field season and during the winter the Heads of Parties will compile reports on the ground surveyed by the officers under their orders. This report should be submitted to the Chief of the Department by the 1st March. T. HENRIONET, Captain of the Staff, Director of the Topographical Operations . 175 REPORT ON THE CARTOGRAPHIC APPLICATIONS OF PHOTOGRAPHY. APPENDIX D. SPECIMENS OF THE FIELD BOOKS, &c., USED IN THE BELGIUM SURVEY. SPECIMEN No. I. Specimen of the keeping of a Register of the genei'al Levelling . Survey of the Camp of Beverloo Field Book No. 1. War Department Levelling Circle No. 25. Topographical Levelling 1847. Mr. Deroisin. Survey No. 6, from St. Trond to the Northern Canal. Levelling of the part comprised between the kilometric boundary No. 62, on the road from Tirlemont to St. Trond, commune of St. Trond, and the boundary No. 65, on the road from St. Trond to Hasselt. Received at the War Department the_ Mr.___dated the, .with the letter of Y 177 . . ,, Numbers (A—2) U> to (A—1) i—* of the points. REPORT ON THE CARTOGRAPHIC Designation of the points. Back reading. Point of departure, milestone No. 62, on the road from Tirlemont to St. Trond. Foot of the staff placed on the summit of the stone. Church of St. Jacques, on the road from St. Trond to Hasselt in the hamlet of Schuerhoven, commune of St. Trond. The foot of the staff placed on the middle of the door-step of the church. Church of St. Jacques Milestone No. 65 on the road from St. Trond to Hasselt, commune of St. Trond. Foot of the staff placed on the base of the stone .. Forward read¬ ing. 0-476 3*1195 1-159 3-525 1-265 0-4755 0-252 3-2715 0-5265 2-7195 1-626 0-704 3-859 0-431 3*7445 0-381 0-434 2-3315 13-3420 169585 133420 dN,=- 36165 0-679 3636 0-6085 1-320 0-5130 1-7945 07610 23335 01945 26715 0-908 1-476 3-6640 13-2315 3-6640 APPLICATIONS OF PHOTOGRAPHY. Reduction to the plane of comparison. Drawing of the objects and position of the staff. N 52*84 dN, = — 3*6165 1 dN 2 = — 3*6135 Sum — 7*2300 dN = — 3*6150 ! N = 52*8400 | N, = 49*2250 ! J (A — 1) d N, — d N 2 = Sum — dN == N = — 9*5675 — 9*5660 — 19*1335 — 9*5667 49-2250 39-6585 (A—2) Remabks. Thursday, April 12, work commenced at 9 o’clock in the morning. Weather cloudy and cold. ! Noon, great heat. 179 REPORT ON THE CARTOGRAPHIC Numbers the points. Designation of the points. Back reading. Forward read¬ ing. JL O T 3 Milestone No. 65. 1-4730 0*9055 2*6905 ST i 21*205 0*219 1 g 0*5375 18*235 0*5495 1*9390 1*2355 3*7320 2 Church of St. Jacques 0*7705 13*7835 4*2175 4*2175 9*5660 & £ • t 3 II 2 Church of St. Jaeques 2*3545 0*4035 • 0*2165 3*651 i ! 0*3705 6*635 2*1595 2*577 0*392 0*5565 I 2*8960 pH 1 0*5405 i g 2*5500 0*8645 0*1935 1*2230 2*6910 0*6560 1 Milestone No. 62, point of departure 3*1785 0*6235 17*6730 14*0595 14*0595 3*6135 =dN 2 180 APPLICATIONS OF PHOTOGRAPHY. Reduction to the plane of comparison. Drawing of the objects and position of the staff. (R-2) Remakes. (R- 1) 5 o’clock, fine weather. 181 REPORT ON THE CARTOGRAPHIC RECAPITULATORY TABLE Of the points of the general levelling contained in Field Booh No. 1. Numbers of the points. Designation of the points. Altitudes. Pages. 1 Milestone No. 62, point of departure 52-8400 2 1 2 J Church of St. Jacques 49-2250 4 3 : Milestone No. 65 ... 39-6583 6 182 APPLICATIONS OP PHOTOGRAPHY, SPECIMEN No. 2. Polygon No. 3. Departure, point of the general levelling ... ... 59*32 K A. 393*50 100*09 171*00 1*19 1*50 0*56 58*76 58*77 High road. K I. 363*25 101*07 56*00 id. id. 1*14 68*18 B A. 193*50 100*34 164*00 1*23 id. 1*14 1*0 59*90 69*92 Intersection of the two Toads, B C. 24*25 99*98 203*00 id. id. 0*20 59*70 69*73 Road. D C.. 211*25 100*17 452*00 1*28 id. 1*42 ... 61*12 61*16 Road near the finger post. * * * * * * * * * * * R S of Polygon No. 1 259*60 99*69 163*50 id. id. 0*56 60*21 60*33 Traverse No. 1. Point of departure 0 of the Polygon No. 1 ... ... 59*50 O a ••• 381*50 99*75 280*00 1*27 1*27 1*11 ... 60*61 60*62 a i ... ”! 75*75 99*42 132*00 1*31 1*50 1*00 61*62 a b 379*25 100*03 197*00 1*30 1*30 009 60*52 60*53 b i ... 82*25 99*32 159*00 id. id. 1*60 62*13 b c. 383*25 100*02 410*00 1*33 id. 013 60*39 60*40 D cof Polygon No. 3 157*00 100*29 118*00 1*28 id. 0*76 ... 61*15 01*16 Traverse No. 2. Point of departure a of the Traverse No. 1 60*62 b 103*00 I 100*68 I 73*00 I 1*31 1 1*31 -1 0*78 I | 61*40 1 61*40 | b i B of Polygon No.3 l 338*25 100*35 203*00 id. id. 1*10 60*30 60*30 c 271*50 1 100 *13 | 184*00 1 id. 1 id, I ... 1 1*38 I 59*92 1 59*92 j Traverse No. 3^ Point of departure E of Polygon No. 3 ... 61*05 a E. 384*50 100*10 | 82*00 1*35 1*50 0*27 ... 61*32 01*32 a b. 143*00 99*89 137*00 id. id. 0*08 ... 61*40 61*40 b 51*25 98*68 70*00 1*27 id. 1*22 62*62 62*60 c b ... ... ,.. 330*25 100*06 120*00 1*29 1*50 0*31 ... 61*71 61*72 c d. 119*50 99*93 196*00 id. id. 0*01 ... 61*72 61*73 e d. 386*25 100*00 194*00 1*31 id. 0*19 61*91 61*92 f e. 365*40 99*97 224*00 1*25 id. 0*13 62*04 62*06 f i . 186*90 102*35 32*00 id. id. ... 1*24 60*82 f g .<. 159*50 10005 173*00 id. id. ... 0*38 61*62 6P68 g 276*25 99*62 130 00 1*23 id. 0*51 ... 62*10 h g. 365*40 99*98 156 00 1*28 id. 0*17 61*83 61*85 h 1 N of Polygon No. 3 16375 100*30 192*00 1 id. id. 1 12 6071 6073 At the side of the road. At the side of the road. War Department. Itinerary of the Route from REPORT ON THE CARTOGRAPHIC o 5 73 r o ®-g > a 0 © «S § a a, * O &0 ...hS 0 73 __.SS-Soag-gT! ro J3 CO r] o rQ g-^ o Sf^ ilfl i2i‘§ - O ^ ® ® ®o ca ft 55flsi.§afl55>s rt+s o at 3,£ p. et ®-*1,0+3 fl «® •Ji-S3 gij «si3 0 t 3 «s a a o-gs rO © flgt; rg gS os 184 o -3 O 73 ’ o£«Hrfl rl iJ O +* g .-S CD rj Sc--* fl „ sag d“® •Sdd ^ a .2 a 2 =f 73^3 o O o ^ 73 g 1 ,§ a % a •Ssll H o^bc^a »+* a a SS tc 05 .73 »‘5>g ®.S ~ r/3 Q Q &-< ,gj ^ ^ c3 o^ O Ou « P--3 C3 fl .5? CS +3 jj £ieS ft ®g JS ' 0 o • 350,0 .^Js ©£ 0*73 "o a a £2'® 04 - g ►T" o „ r .« §>o>© ©«3 - 0,0 •■> g u .„_” . a 73 ~ cs 73 ® 'id 1 -t e Z, a 3 S a > a,o~=i oS p«3 *. A Extent and Cultiva¬ tion OP THE LAND. & SP Population. RE- Foe the Lodging- Houses. Foe Feeding O) CJ s « 0 Total surface- Land annually fallow. Land fit for cul¬ tivation. Vines -Meadows Artificial mea¬ dows. Various cultiva¬ tions. Woods Wastes Marshes I Tanks Quarries Turfpits Coalpits Mines Total Cultivators Tradesmen Artisans Attached houses Scattered „ Fires Churches Convent of Castle of Hospital Covered Markets Establishments of Inns Barracks Drinking places Fountains Wells Cisterns Aqueducts Canals Mineral springs Running waters Note.—M en¬ tion whether the waters dry up during the dry weather. Wheat Rye Maize Rice Oats Barley Buckwheat... Country bread Flour Potatoes ... Salt Straw Hay Wine Oil Brandy Beer Cider Oxen Cows Sheep Pigs Goats 186 APPLICATIONS OF PHOTOGRAPHY, No. 5. Table. size, and opening under the titles of the columns, which thus will not have to he each sheet. SOURCES. Observations. AND WaBMING. { Foe Carriage. Foe the eenewing and be- PAIR OF CLOTHING, BOOTS, ABMS AND CAEEIAGES. ence the goods it necessity, of these Warming. C4-4 O go S A 0 £ O i & d$g GO 72 c3 H3 CD A £ W ^ d 'S cu ri 2 OS ^ r-e s T5 a d Nature of the Combustibles. CD Fh o II ice per unit of j measure. J iture of the me carriage. CD rO s tablishments and men. lantity turned annually. rice per unit of n .aily wages of the nt workmen. lint out the ph commune obtain requires of the g the kind and qi goods. O o* J Ah & fl TJ1 w Q* S' 0 ® Fm Ovens. Wood Horses s rcioth Private Coal Mules I'SH Calicoes Public Turf Asses ^ ^Leather Bakers’ Draught oxen Forges and Ma¬ nufactories Total fl 1 iv 1111 & wxiueis each loading Shoemakers ... Baking in 24 hours. Quantity "1 of flour 1 which | the bakers }■ should have in | advance. J Mills. & o c3 t. *5 ° 11 With 4 wheels 1 each loading Tailors Armourers ... Blacksmiths ... Daily hire per) collar J Boats carrying Carpenters ... Farriers Sailors Boatmen Water Wind Others Total Grinding ) in 24 > hours. ) Mean 's grinding f per an- f num. ) I | 187 REPORT ON THE CARTOGRAPHIC APPENDIX E, 1.—TRANSLATION OF A PAMPHLET BY HERR A. MEYDENBAUER, “ ON THE APPLICATION OF PHOTOGRAPHY TO ARCHITECTURAL AND LAND SURVEYING,” published in the Zeitschrift fur Bauwesen (Architect’s Journal) 1867, parts 1 and 2. In the year 1835, before the invention of photography, Beautemps Beaupre had conceived the idea of constructing a topographical map of a country from drawings taken in perspective from different points of view. The application of this idea in practice was completely frustrated owing to the natural imperfections of drawings executed by hand. Laussedat, battalion-chief of the corps of Engineers and professor of geodesy in the Polytechnic School at Paris, followed up the idea in the year 1854; and by means of the introduction of the camera clara, pro¬ duced some better results. This application of photography was but a small step in the right direction, for the photographic image is merely the fixed image of the camera obscura , of which the camera clara is only a modification. There is this disadvantage, however, that the image given by an achromatic and spherical lens and its combinations as used until now in all optical and photographic instruments, is only exact within an angle of 20 degrees; moreover, LaussedaPs improve¬ ments have not yet been brought to any practical result, at least little is known as yet concerning them. The first notice of it in Germany was in the “ Photographischen Archiv” of September 1865. Without being acquainted with Beautemps Beaupre's or LuussedaPs labours, the author, during a survey of mediaeval buildings, met with great difficulties in obtaining measurements of inaccessible heights without scaffoldings ; and he hit upon the idea of applying mathematical methods for which the present perfect state of photography offers the most reliable basis. All that was required was a reversal of the method followed in constructing perspective drawings. A specimen of this method of surveying was exhibited at the photographic exhibition of last year in Berlin. By accidentally looking at two photographs there, representing an inaccessible peak of the Alps from two different points of view, it became 188 APPLICATIONS OP PHOTOGRAPHY. apparent that by means of a generalized, or rather, simplified application of the same process, it was possible to construct a very accurate map of this inaccessible peak with all its details, and even with horizontal con¬ tours, a work which could not be done in any other way so quickly and with such precision. The production of this topographical survey from ex¬ isting photographs, was however not so simple as it seemed to be at first. The photographic camera must, for this purpose, be set up on a suitable stand, similar to that of a surveyor's plane table, and it must be furnish¬ ed with special internal arrangements. The conviction that with an angle of vision of only 20° not much could be done, induced the author to abstain for a time from further costly experiments. Sometime after Mr. Busch of Rathenow brought out his Pantoscope, a new photographic ap¬ paratus which produces an exact perspective picture within an angle of vision of 90° or more. With this instrument, the performances of which elicited the astonishment of all competent judges, the application of photography to Architectural and Land Surveying, or Photometrography is only a question of time. In France, photometrography is already practically employed by the corps of Engineers, notwithstanding its pre¬ sent imperfect state, and in Prussia also, it had attracted the attention of the War Department, but on the outbreak of hostilities, it was laid aside. It is not the purpose of this paper to give an exhaustive statement of these photometrographical processes. For that a new treatment of perspective on the one hand, and of surveying with the plane table on the other, would be required. We presume that our readers are acquainted with both of these subjects. The photographic apparatus in its most simple form the well known camera oibscura , depicts an image of everything present in its field of view, and this image is in correct perspective within an angle of 90°. To ascertain the accurate measurement of an object pourtrayed photographic¬ ally, nothing is required but a reconstruction of the perspective. This science as part of the study of projection, has hitherto only been developed in one direction, viz., the representation of given geometrical objects in Central Projection. The contrary direction, that is to say, the represent¬ ation of given perspective objects in Normal Projection , is certainly just as desirable, and, as will be shewn hereafter, of far higher practical worth. 189 REPORT ON THE CARTOGRAPHIC For the construction of perspective as well as for its re-construction, certain geometrical elements are necessary, (see % 1). T Of these the Horizontal Line HIT, the Prime Vertical W, their point of intersection, or the Point of Sight 0, require no further expla¬ nation in this place. We call every horizontal line, drawn in the picture plane a Ground line . Distance is the normal interval between the station point and the picture plane. The following simple laws of perspective will be applicable. 1. All parallel and not vertical lines seem to vanish in one point of the picture plane; if they are horizontal, this point, the Vanishing Pointy is on the horizon. 2. Let fig, 1 represent the perspective image of any given horizon¬ tal AB and on the same a part of it ah. It is required to ascertain the absolute length of this portion according to the scale of the picture, which cuts the horizontal in the point A, the distance s being also given. Lay off the distance s from the point of sight O to S upon the Prime Vertical. Then draw through the point A a ground line A D and with the distance B S as radius strike an arc to C on the horizon. The point C is the Dividing point for the horizontal A B and all lines parallel to it in the same distance. Draw from C through a and h to a f and h' , and a ' h ' will be the length of the perspectively shortened distance a b> on the scale of a picture plane passing through the point A. 3. To find the angle which the horizontal A B makes with the normal from the station point to the picture plane, draw from S to B and O S B will be the required angle. 190 APPLICATIONS OF PHOTOGRAPHY. Fig*. 2. It follows from this that the angle BAG, (fig. 2) which is formed by the two horizontals,, will be found in its absolute size, if a line is drawn from S to B and from S to C. The angle BSC is the required angle. Fig. 3. 4. If we have (fig. 3) the perspective of a figure abed on a horizon¬ tal plane, but which approaches so very near the horizon that the lines cutting one another form angles too obtuse for working with accuracy, the horizontal plane with the figure is transposed vertically somewhat higher or lower as a ' b' c f d'. Each single line of the figure abed is thus brought into a position perfectly parallel to its former one and therefore retains the same vanishing point. The figure a' b' c! d' permits of the same operations as that origin¬ ally given, but under much more favourable circumstances. On this de- 191 REPORT ON THE CARTOGRAPHIC pends the method of perspective groundplans, which by the reduction of the perspective attains a far more extensive application than has hitherto been obtained by perspective drawing. Let us now consider a photograph by means of the geometrical representation of the photographed object. This object can be selected to exhibit sharp, distinct straight lines, from which we can assume that they are accurately horizontal or vertical; as, for example, buildings and machines. It is natural that we should use these lines for the reconstruc¬ tion, and we can sometimes, but not always, obtain the required elements by this means. But in a landscape the elements for the perspective are not generally given, perhaps nothing else than the horizon in a pic¬ ture which shews the open sea. Therefore without something further we can do nothing with the photograph. (Fig. 4.) But let us bear in mind that the image of the camera obscura as a correct perspective must originate as we imagine central projection, that is, the intersection of a plane with the pyramid of visual rays to be developed. The optical centre S of the apparatus (fig 4.) is the station point in a perspective sense, the sensitive surface of the apparatus, is the subsequent picture plane. The length O S from the optical centre is the Distance. If when taking the picture the camera has been placed perfectly horizontal by the means usually employed in surveying with a plane-table, and the distance between the optical centre and the image has been correctly measured, then there is no doubt that we can indi¬ cate on the picture all the necessary elements for reconstruction. The Horizon H H, and the Prime Vertical Y Y, are marked automa¬ tically on the sensitive surface during the taking of the picture by means of fine wires placed close in front of it. They appear on the picture as fine black lines and represent in every respect the cross wires of a theodolite. The Distance O S should be measured directly in the camera and with the greatest care. In the photographic apparatus which should 192 A3F>2?&Hd) a day. In the event of a higher rate, the charge is required to be certified by the local magistrate, that (c persons for this purpose cannot be obtained at a lower rate.” Temporary servants (generally officers* servants) receive for their services 74 sgr. (9 d) per day. Note .—When the wages agreed upon, particularly for carrying instruments, have been paid, they are not to he expressed in the vouchers in one sum with the number of days, hut should be specified and stated for each month separately, and not from one month to another {viz., not from July 25th to August 10th.) All receipts must be dated from the last working day. Accounts for materials , required for erecting stations, signals, &c., &c., during the survey, must be properly specified and cannot be paid for without the quality and price having been duly authenticated by the local magistrate or other competent persons, or if necessary by the officer. In entering into an agreement for the building of stations, it has to be made a condition that the materials shall be returned to the contractor, who has to make due allowance for the returned materials and deduct the same in his account. A detailed statement of this should appear in the vouchers. If, however, the stations or signals are required to remain until the following surveying season, it should be stated in the documents, and in such a case, every effort should be made to interest the local magistrates in the preservation of these stations. If any compensation for stolen materials, i. e., stations or signals, is required, the local magistrate should be informed of the theft It must be stated in the vouchers that such information has been given, as well as the steps which have been taken to discover the thief and their result. Vouchers referring to expenses which have not been especially enumerated are required to be certified as follows :— “ That the object of expenditure was required and could not be ob¬ tained at a lower price and also that the amount has been paid.” For the convenience of officers, as well as to obtain perfect uniform¬ ity of documents, the Survey Director will supply the necessary forms, but care should be taken that they are filled in correctly when transmit¬ ted, without having occasion to return the same for correction. . 207 REPORT ON THE CARTOGRAPHIC 3. The travelling expenses for officers and assistants from the garrison to the surveying station and from thence to Berlin are defrayed by the respective regiments. After the termination of the survey, the officers will receive the marching order for assistants from the Survey Director. The assistants are only permitted to travel by rail, steamer, or post, if the service is really benefited by such mode of travelling; and this has to be decided by the officer of the section, who would have to certify the steps taken in this respect by the Survey Director, in case it should be required. In such cases, the exact expenses for travelling are required to be made on special vouchers, because the payment of the fixed rates of fares for non-commissioned officers and privates depends on the sanction of the War Department. CHAPTER II. Relating to the time of Residence in Berlin. officer^to report § VII. Officers having returned from the survey have personally to themselves. report themselves at the office of the Commander-in-Chief and to all the Staff Officers of the General Staff, and observe in this respect the general regulations of the service. §8 office hours & VIII. The office hours extend from 10 a. m. to 2 p. M., unless and occupations. s _ * otherwise directed by the chief of the department. During the months of November and December, these hours are generally only to be occupied with penning in and finishing the plans and other writings relating to the topographical survey. In January commence, in addition to the above, the studies of tactics under the officers of the staff, and after¬ wards under the Commander-in-Chief. In case the plans should not be finished during this second period, the days not required for the study of tactics are to be employed in finishing the same. After the plans and other topographical works are completed and deli¬ vered to the Survey Directors, officers will be transferred to the divisions of the General Staff for further employment. The plans and other topographical works are required to be finished and given up on or before the 21st December, that is, if the topographer has surveyed not more than one section, but for those whose survey comprises more than one section, or contains some intricate details, the giving in can be deferred until the 20th January. 208 S APPLICATIONS OF PHOTOGRAPHY. § IX. Officers* servants are subject to the orders issued by the War § officers’ 5 ° servants. Department, but on particular occasions, when their services should be re¬ quired by officers, proper information will have to be given to the respective Survey Directors. § X. The receipts for monthly surveying pay must be collected for §io- each division (dated on the 1st of the month to which they refer), and payofoffleer8 * delivered on the 25th of the preceding month in the Plan Depot of the General Staff. On the 25th of each month, the service pay list will circulate for signature in those divisions of the General Staff in which there are officers commanded for surveying service. From the 26th to the end of the month this document will be in the office of the Topographical Department where signatures which are wanting can be supplied after 1-45 p. m. It is not permitted to send the pay list to officers* quarters. Those prevented by illness, &c., &c., are required to send a special receipt at the proper time. In order not to delay payment to the inconvenience of all, the names of those officers, who shall not have fulfilled the abovementioned regula¬ tions will be struck out from the list and can only receive payment in the following month. Each alteration (affecting pay, change of service, departure, &c., &c.), requires to be communicated in writing, with the respective order, date, &c., &c., to the office of the Topographical Department. On arrival at Berlin in the month of November, officers are request¬ ed to report themselves immediately at the Topographical Office, because their assistant is not entitled to receive pay for more than three days after the officers report. Any loss arising from a delayed report will have to be borne by the respective parties. § XI. Application for leave of absence for not more than 8 days § 1L Leave * can be made to the Survey Director, but for a longer period it is required to be made to the Commander-in-Chief according’ to the regulations for the army. § XII. All verbal communications to the registrar as well as to the § 12 * Working draughtsmen in the Topographical Department are required to be made JjpSJent?* 1 before 10 a. m., or postponed to from 1-45 to 2 p. m., otherwise the service would suffer from continual interruptions. The registrar and draughts¬ men are earnestly requested to refuse every enquiry which is made at any other hour. a o 209 RPORT ON THE CARTOGRAPHIC §13. Require¬ ments from offi¬ cers ordered for surveying duty. § 14. General arrangement of the surveys. B REGULATIONS REGARDING SURVEYING. CHAPTER I, General Observations. § XIII. For such an important employment as military surveying, the results of which are published, and therefore subject to general criticism, the greatest care and accuracy in execution is absolutely required, even if officers, &c., ordered for the performance of this duty, should not bear in mind the important influence which a display of extraordinary capa¬ bilities might perhaps exert on their future career. It is expected that every officer ordered for this service possesses a knowledge of the theory of surveying and of other operations connected with it. § XIY. The division of the Military Topographical Survey into plane table sheets (sections) is based on the known divisions of longitude and latitude. The space of 1 degree of latitude and longitude is divided, the former into 10 and the latter into 6 parts, forming, therefore, 60 equal divisions (plane table sections), as shown in the annexed figure, supposed to include latitude 49° and 50°, and longitude 25° and 26°. The designation of each section is expressed in the following manner, 5Q0 namely, each division of the latitude is called 54' “part” and of the longi¬ tude “ sheet ” For ex- 48 ample, the section mark¬ ed Kreuznach * would be designated as follows :— 36 » Degree £§• Latitude, 25-26° Longitude. Part 30' IX. Sheet 4, or abbre¬ viated, Degree 50-26°, 24 ' IX, 4. The original drawings, 18' surveyed on the natural 12 ' scale of 2 T reduced for engraving to 6’ ooTiTTo* for Rhenish o Prussia and Westphalia ; and xooVcJo * or the 50° 25° 1 6 26 Kreuz¬ nach.* 1 1 X IX VIII VII VI V IV III II I 490 250 2 ( APPLICATIONS OF PHOTOGRAPHY. Eastern Provinces, and form the so-called Grad A htheilungs Kart 3 or Degree Maps as described above. § XV. Each officer, before his departure to the section, will receive § 15 - In3 j rn * from the Director the necessary surveying instruments for which, as well tenal3, as their being in working order, he is required to sign a receipt or form, in which the number which each instrument bears must be inserted. Officers must be convinced that the instruments are in proper order, as they are responsible for the same, unless damaged by unavoidable accident. If such damage should have arisen from carelessness only, officers are obliged to bear the expenses of repairing them. The u kippregeP itself is, as a rule, never to be trusted into the hands of the assistant, and is always required to be taken from and replaced in its box by the surveyor himself. On occasions of inspection during the surveying season, the Survey Director should personally ascertain the state of the instruments in charge of the officer. The return of topographical instruments, after the close of the survey, is to be made in the following manner - The delivery of instruments by Surveying officers to the Survey Director should occur with the least possible expense at the place appointed by the latter for receiving the same, either personally or by transmission; in which case officers will be held responsible for their being properly packed. In packing up the “ kippregel,” the surveyor should enclose in the box a note on which is mentioned the error of the instrument, if any should exist, or that it is without an error. Officers are required to forward an ex¬ act list of the instruments, giving the number with which each is marked. Each officer receives of printed matter— 1 Skeleton sheet of the section to be surveyed, containing the elevations and distances of the trigonometrical points and serving for the preparation of the detailed ground plan. 1 Note-book for surveying with the kippregel,” 1 “ Kotentabelle^ or tables of sines and tangents, 1 Table of tangents with directions for its use, 1 Instruction, 1 Set of specimens. Other instruments, utensils, and materials, which are used for sur¬ veying and drawing, are enumerated below, to indicate the general requirements. The surveyor has to defray the expenses for these himself, and receives one thaler (= 3 s) per month only as a compensation for drawing materials— Umbrella, covered with grey linen. 211 REPORT ON THE CARTOGRAPHIC Tin case, two feet long, three inches diameter, for preserving paper and drawings. Sketching case, fitted to hold a pair of compasses, pencils, India rubber, penknife, eraser, and file. A pair of compasses. Drawing pen (Dresden.) Brushes and handles for the same. Saucers for colors. Penknife and eraser. Paper-cutter. Sharpening stone. File for sharpening* pencils. Mouth glue. Gum Arabic. India rubber and chamois or wash leather. Spunge for cleaning the plane table. Straight edge, 8 inches long. Triangle „ 3 and 5 inches long. Bottles to preserve mixed colors. Pantograph (indispensable for reducing drawings) can be best procured from Liittig in Berlin, Post-Strasse , No. 11. Smooth wove drawing paper. Tracing paper. Oil paper, or cartridge paper, to preserve the drawing of the plane table. Squared paper for sketching. Note books. 1 piece Indian ink. (Dissolved Indian ink should never be used, as it never properly dries. An outline made with it will always run or spread, if a drop of rain should fall on it, or if a brush with color touches it. Indian ink should be rubbed up new every day, and the saucer previously washed). 1 cake of Carmine. 1 do. Vermillion. 1 do. Haw Sienna (for roads), 1 do. Minium. 1 do. Prussian blue. .1 do. Gamboge. APPLICATIONS OF PHOTOGRAPHY. Meadow green, village green, and both tints for forest trees are, for the sake of uniformity, to be obtained from the Topo¬ graphical Department at Berlin. Pencils, Faber, No, 1, for transferring. „ „ „ 2 „ drawing. „ „ „ 3 „ writing. }} ,, ,, 4 „ triangulation. Note. —Experience has shown that all materials can only be obtained at Berlin of as good a quality as is really required. So called “ station needles” are not permitted to be used. § XVI. The cross-wires in the telescope of a “ kippregel” consist of § 10 .- 3 Measuring 1 dis- one vertical and three horizontal wires, and for ascertaining any distance ta ?? es witl F h ® „ ° J “ kippregel and these horizontal wires and a surveying staff alone are used. surveying staff. This staff is divided into 80 inches, and each inch, visible be¬ tween the two external horizontal wires, indicates a distance of one rood ;* if the whole range of the staff (80 inches) is visible between these two wires, the distance amounts to 80 roods. Each inch on the staff visible between the centre wire and one of the outer horizontal wires indicates a distance of 2 roods, therefore at a distance of 80 roods, half the staff, and at 160 roods the whole staff will be visible between the same two wires. It is desirable to accustom oneself to reading off the distances only in the last-mentioned manner, partly in order to avoid any mistake, partly because the divisions on the staff (every 5 inches=10 roods, dis¬ tance) greatly facilitate the reading off in this way. § XVII. When observing angles with the “ kippregel,” the tele- § i 7 .-Reading scope is placed in such a manner, that the central horizontal wire exactly v«n£r! Applies* r J ^ on °f t ^ ie an £* e intersects the object, and then the angle is read off on the vernier. °f correction. The graduation of the index is not always the same in different instruments. A. —On Lewert's “ kippregel” each degree is divided into 3 parts or 20 minutes, and the arc is read off from the large to the small zero- first the number of degrees, then the parts, whether 20 or 40 minutes, and after having estimated whether the remainder is above or below 10 minutes, it is read off forwards on the vernier, if between 1 and 10 minutes, or backwards , if between 11 and 19 minutes. B. —On PistoFs, Breithaupt's, and Baumann's “ kippregel,” the de¬ grees and parts of degrees are read off on the arc from the large to the small zero, (marked by arrows) and the minutes on the vernier. * L rood=12 Rhenish feet, or 12357 English feet=4*119 yards. 213 REPORT ON THE CARTOGRAPHIC Angle of Correction .—It is but very seldom that the plane table is placed in a correct horizontal position, therefore the angle, which the table forms with the horizon, should always be taken into account when observing for elevation, and this (the angle of correction) is ascertained by levelling the telescope, which is provided with a small level either above or below the same, when the angle is read off on the vernier. The application of this angle of correction is always treated al¬ gebraically, that is, if the signs are like , the angle is subtracted, and if' the signs are unlike , it is added. Let W be the measured angle which requires to be corrected, C the angle of correction, and R the corrected angle. Then we obtain the following 6 cases 1 ,W= + 1° 20' C = + 0° 10' 2 . r = + 1 ° 20 ’ C=— 0° 10' R = + 1° 10' R = + 1° 30' 3. W = — 1° 20' C = + 0° 10' 4. W = — 1° 20' C - — 0° 10' R= — 1° 30' B = — 1° 10' 5. W = ± 0° 0' c— + 0 ° 10 ' 6. W = ± 0° 0' C ~ — 0°10' R = — 0° 10' R = + 0° 10' § XVIII. Before departing for the surveying station, every Officer is required to ascertain if the instruments which have been delivered to him are in good working order; if otherwise, the Director of the Survey must be informed of the faults. I.—THE « KIPPREGEL.” A.—The vertical wire .—In order to test if the wire of the in¬ strument is exactly vertical, the plane table should be carefully levelled and the telescope directed to a long vertical line, slowly elevating or depressing it; if the wire covers the line, the adjustment is perfect. To ascertain if the line of vision coincides with the edge of the rule, place two poles some distance from each other in the direction of the 214 APPLICATIONS OF PHOTOGRAPHY, line of vision, and draw a line; then reverse the rale, place it on the same line, and erect a third pole accordingly; if the instrument is correct, the third pole will he in line with the other two. B. —T/ie distance meter .-—-In order to ascertain if the horizontal wires, which indicate the distance by means of the staff, are placed correctly apart, the best way is to place the “ kippregeP at a milestone on a straight horizontal metalled road, and move the staff successively to measured distances of 20°, 40°, 60°, &c., &c., towards another milestone, and then test whether the staff reads the same. When there is no such road, then a line must be measured, or the correctness of the wires can be tested by comparison with other in¬ struments. C. —The angle of divergence .—It will be requisite to ascertain whether the line of vision on the central horizontal wire is exactly horizontal, or forms an angle with the horizon (angle of divergence), when the telescope is placed perfectly horizontal by means of the attached levels. As it will be difficult always to obtain a distinct point, which exactly coincides in height with the axis of the telescope, the correctness of the instrument is tested by measuring the same vertical angle forwards as well as backwards. The plane table with the “ kippregel 33 is placed at a point A, and the height of the telescope is carefully marked on the staff which is then placed at another point B ; observe carefully the angle which is formed by the line A B and the horizon, and apply the angle of correction, then place the instrument at point B , and the staff at A, and repeat the observation. If no angle of divergence exists, then the angles will be the same in both cases, only with different signs. If the angles are different, the instrument has an angle of divergence; the correct angle is then obtained by taking the arithmetical mean of the two angles. The extent of the angle of divergence is the difference which exists between each of the measured angles and the correct angle. The angle of divergence is positive ( i. e., the axis of the telescope forms a positive angle with the horizon), if the measured angle of eleva¬ tion is smaller than the measured angle of declination. But the angle of divergence is negative {i. e. } the axis of the telescope forms a negative angle with the horizon), if the reverse is the case. With a positive angle of divergence, the angles of elevation mea¬ sure too little, and the angles of declination too much, therefore the as- 215 REPORT ON THE CARTOGRAPHIC certained angle of divergence must always be added to the angles of elevation, and subtracted from the angles of declination. If the angle of divergence is negative , then the reverse will be the case. For Example. —On testing the instrument, the first angle was found to he ... ... ... -j- 2° 6' And the second angle ... ... ... — 2° 18' Then the correct angle will be ... 2° 12' or the arithmetical mean. The angle of divergence (difference between the two measured angles and the correct angle) would, in this case, amount to 6', and as the mea¬ sured angle of elevation is smaller than the measured angle of declina¬ tion, it follows that the obtained angle of divergence is positive (+ 6'). Therefore, each angle of elevation is by 6' too small, and each angle of declination by 6' too large, consequently, for correct results, the ascer¬ tained angle of divergence of 6' is additive in the former and subtractive in the latter case. If the signs in the above example were reversed, then the angle of divergence would of course be negative ( - 6'). D. — The compass. —It should be ascertained whether, when the plane-table is perfectly horizontal, the magnetic needle swings freely and indicates quickly and distinctly its position, or if any mechanical defect (of the pivot, cap, &c., &c.) prevents its playing freely. All faults and injuries of the e< kippregel” should be communicated to the Director. Officers are not to attempt the repairing of the same, nor is it to be trusted into the hand of a mechanician without permission from the Director. The remainder of the instruments, such as stand, measuring staff, plane table, should be carefully examined, particular attention being paid to the screws, as to their being in working order. §19. Manuals or § XIX. H. v. Plehwe. — Guide for Instructions in Military Survey- treatises on sur- ° j ve ying. Berlin, 1859. This work can particularly be recommended on account of its short, concise and general outline, comprising everything important. Surveying with the u kippregel 33 has been specially treated. 2. H. v. Plehwe. — Guide for Instruction in Flan-Drawing, 3rd edition, Berlin, 1854. Besides the ordinary manner of representing the country, the method of equidistant horizontals is discussed. 3. P. A. v. Etzel. — Land Surveying, 3rd edition, 1850, forming also the IXth volume of Hand Library for Officers. This work contains 216 APPLICATIONS OF PHOTOGRAPHY, the principles of land surveying, and so much of geognosy as to give a preparatory knowledge of topographical surveying, 4. H. v. JSoim.—Land Surveying , containing a description of the representation , reconnoitring and survey of a District , prepared with particular regard to the Topographical Survey of the General Staff. Those who desire still further information regarding every instru¬ ment used for, and the different methods of, surveying will obtain such for all practical purposes, from the following works 1. C. F. Schneitler. — The instruments and materials used in the higher and ordinary branches of surveying; as well as the art of geo¬ metrical drawing. Leipsic, 1852. New edition. 2. C. F. Schneitler.— Manual of Surveying , or Description of the Theory and Practice of all methods of surveying , levelling and measuring of elevations of military surveys , also surveying of boundaries and very extensive territories. Leipsic, 1854. 2 nd edition. 3. C. M. Bauernfeind. — Elements of Surveying. Munich, 1856. CHAPTER II. On the Prosecution of the Survey. § XX. By reconnoitring the section (district to be surveyed), some ? 29 . Eeeon- knowledge will be obtained of the general features of the country, which section and test- < ° ° J J in® the trigono- will assist in carrying out the plan on which the survey is conducted. metrical points. At the same time, enquiries should be made regarding the means of communication, residence of the persons employed on the survey, facilities for obtaining quarters, names of places, &c., &c. On this occasion, the correctness of the trigonometrical points on the plan should be tested in the field horizontally and vertically. (The topographer should previously ascertain that the trigonometrical points are correctly laid down on his plane-table section by comparing their distances with the latitudinal and longitudinal distances given on the special skeleton chart). The most accurate manner of testing this, is by placing the instru¬ ment at one or more fixed trigonometrical stations, from which several of the other stations are always visible. The straight edge attached to the “kippregel” is placed on the plan ex¬ actly on the station where the instrument stands, and on a second visible tri¬ gonometrical point; then the table must be so adjusted that the vertical cr oss¬ wire of the telescope exactly intersects this second point. By again a 4 217 REPORT ON THE CARTOGRAPHIC placing the edge of the rule on the first station and a third visible point, the cross-wire should also exactly intersect the corresponding station. Now that the position of the plane-table exactly coincides with the respective trigonometrical points, unclamp the magnetic needle, and move the rule gently about the centre of the table, until the needle has settled exactly at zero ; then draw a pencil line with the rule on the north and south margins of the plan, and insert on this line the date and hour of ob¬ servation. This magnetic line should be drawn through the north and south margins of the plane table section itself and not on the given skeleton sheet, and must be inked in as soon as possible to prevent it being obliterated. As the direction of the magnetic needle is not con¬ stant, these observations require to be repeated several times, in order to obtain as correct a mean as possible. The hour of the day influences greatly the magnetic needle; about 10 a. m. is the most favorable time for such observations. The direction of the magnetic needle, i. e. the magnetic meridian of any place, generally differs from the true meridian, and the angle thus formed inclines either to the east or west of the latter. This is called the variation of the magnetic needle. This varia¬ tion not only changes at different places, but also changes in course of time ; however, these changes are so insignificant that in topographical surveying this would only be taken into consideration in case the mag¬ netic needle of the “ kippregel” should have lost some of its sensibility by frequent use. The variation at Berlin amounts to 17J° west, and the extent of the daily variations, that is, the angle between its extreme eastern and western indication is from 13 to 15 minutes during summer, and a little less during winter. If the instrument is placed in the proximity of iron, for instance on spires, balconies with iron railings, near wind-mills, &c., it is well known that the magnetic needle does not indicate its proper direction, and should therefore not be unclamped. In those cases where, for example, a spire has been fixed as a trigo¬ nometrical point, and the surrounding stations can only be seen from the window of this spire, the observations- with the instrument can be made without hesitation from any such window or opening, as the difference compared with the distance is scarcely perceptible. If the correctness of the surrounding trigonometrical points can only be tested by erecting, under great difficulties, the instrument at any of the stations, then it must be done in an indirect manner and by 218 APPLICATIONS OF PHOTOGRAPHY. subsidiary backward intersections to a 4th or 5th station or any other distinct object, easily determined (after which the direction of the magnetic needle must be determined). It is recommended that those stations, which have been found correct, should be pricked through with a fine needle and surrounded with a small circle in pencil. Immediately after testing the trigonometrical points, the Survey Director requires to be informed of the result, accompanied by a state¬ ment of the manner in which the test has been made. In case any dis¬ crepancy should have been discovered, the corrected position in measure¬ ment (roods) and its direction (whether east or west) is required to be mentioned ; any existing differences in the height should be expressed in feet. At the same time a report has to be made regarding the manner in which it is proposed to fill in the detail of the survey after having reconnoitred the section. In case any doubt should arise, about which the officer should desire further information, he should communicate with the Survey Director. § XXI. As the supplied trigonometrical points will not be sufficient § 21 . Geometrical for a detailed survey of the whole section, the Surveyor himself will be (signals), required to fix geometrically a number of additional points. This is accomplished either by “backward intersections” of suitable and distinctly visible points, on which afterwards signals (stations) should be erected ; or by “ cuts” to such objects as spires, single trees, wind-mills, conspi¬ cuous chimneys, &c., &c. In observations of such “ cuts” and “ intersections,” the vertical cross-wire must always intersect the object exactly. In carrying out this geometrical triangulation, it is to be strictly observed as a standing rule, never to fail to test the correctness of the work and to secure it by frequent intersections, at the stations in the open ground of the section. In erecting signals on intermediate as well as principal stations, a point should be distinctly marked by means of a staff or a wisp of straw, &c., and its height correctly determined; likewise those of conspicuous objects, such as church spires, high chimneys, &c., fixed by “ cuts ” as they may be required for ascertaining other heights. § XXII. Among the several methods employed in “ backward § 22. Testing * 0 r J Stations by intersections,” the one, called the “ approximating process,” has proved „ to be the most expeditious and reliable in practice. For such, “ intersections” three stations are required which should form a triangle. 219 REPORT ON THE CARTOGRAPHIC The station to be ascertained can have the following positions in re¬ lation to the three stations :— 1.—It can lie within the triangle formed by the three points. —It can lie outside the same, but within a circle passing through the three points. 3. —It can lie outside this circle opposite any side of the triangle. 4. —It can lie outside this circle opposite any of the angles. 5. —Or it can fall exactly on the circle. If the backward rays drawn from the three given points do not intersect in one point, but form a triangle, (the triangle of error) then the correct point lies— Ad 1.—Within the triangle of error. Ad 2.—Outside this triangle and near the middle line of vision. Ad 3.—Outside this triangle opposite the middle line of vision and within the angle formed by the other two lines. Ad 4.—The same as No. 2. For explanation see the adjoining figure. (Fig. 1, Plate XIII.) A, B , C., are the given stations (objects) Aa, Bb , Cc, the respective visual rays, which show the small triangle indicating the error. Ad 5.—Becomes impracticable without a fourth given station, as the lines drawn from the three stations will always intersect in one point, even if the table were not properly adjusted. The procedure by “ backward intersections” is as follows :— The plane table is first of all properly adjusted and pointed on the selected station by means of the magnetic needle as already described at § 20, the needle is then clamped, and the visual rays are drawn, the posi¬ tion of the resulting triangle of error will easily indicate (if it was doubtful) to which of the above-mentioned cases it belongs. The true position of the point will be ascertained according to cases 1 to 4, on the principle that the distance of this point from each single line of vision is in the same proportion as these lines among themselves, that is, as the distance of the point from the three given stations. The point so indicated is temporarily accepted as being correct, the table is then adjusted in the direction of the most distant given point, and the operation repeated until the lines intersect in one point. As the eye will by practice obtain great quickness in fixing the correct position of the point, this mode of intersection will only be a slow and tedious operation for a beginner, whilst an experienced operator 220 SP3LAMS SEES, Fig. 1 C CL ?4 Fig, l 12hf! / Intermediate ■ . APPLICATIONS OF PHOTOGRAPHY. by always obtaining reliable starting points for his work will gain confidence and self-reliance and thus make far more rapid progress in it. 6 XXIII. After the station has been marked on the plan, its § as. Dctermi- height is determined with the aid of the “ Kotentable.” (The “ kotenta- heigMs * ble” consists of tables of sines and tangents calculated for use with the “ kippregel.") The vertical angle and the angle of correction should be ascertained with great care, and the correction for curvature of the earth's surface, for refraction, and the height of the telescope, be subtracted from the result. The influence of the curvature of the earth has been carefully determined for every latitude by the measurement of different degrees. In the latitude of Northern Germany, the semi-diameter of the earth's figure may be assumed to be the same as the semi-diameter at the equator, or 859*44 German geographical miles, each of which contains 19,702*5 German decimal feet. For such distances as occur in military surveying, the correction for curvature would be in proportion to the squares of the distances. In calculations of points situated above the horizontal plane (there¬ fore positive angles), the correction for curvature should be added, but in cases where they are situated below the horizontal plane (therefore negative angles), it should be subtracted from the result. Regarding the influence of atmospheric refraction (deviation of a ray of light caused by the atmosphere), it requires to be observed that the density of the air increases if an object is seen from an elevated point of view (the one being situated lower than the other), as, according to the well known physical law of refraction, each ray of light passing through the atmosphere deviates from its straight direction in its course between the object and the eye in such a manner that it forms a curved line bent upwards. Therefore, on account of the tangent of this curve, the object is seen higher than it is in reality, no matter whether it be situated above or below the plane of the horizon, i. e., whether the angle be positive or negative. It follows from this, that in calculating heights, the correction for refraction requires to be subtracted from the result, if the angle is 'positive, and added, if the angle is negative. The correction for refraction is also in proportion to the squares of the distances. 221 REPORT ON THE CARTOGRAPHIC b. New signal points. c. Stations where the surveying staff has been erected. The corrections for curvature and refraction are therefore applied in an opposite manner,, that is, the one reduces the other to a certain extent. The correction for refraction does not amount quite to one-seventh of the correction for curvature. In the tables constructed for the use of the topographical survey of the army, the former has already been deduct¬ ed from the latter, so that therefore both corrections for the calculations form one single result. The total influence of curvature and refraction amounts, for example— in a distance of 200 roods 0T0 feet » „ 500 „ 0-64 „ „ „ 1,000 (| mile) 257 „ „ „ 2,000 (1 mile) 10’27 „ The calculation for heights of such points should be made at the least from 2, or if possible, from 8 of the given trigonometrical stations, or otherwise from stations already correctly fixed. If the difference should be considerable, then a mistake must have oc¬ curred somewhere, which requires to be corrected. If the difference should be from 2 to 6 feet, then the mean can be taken as correct; but it should be observed that observations on objects at a short distance and at obtuse angles will always give the most reliable results; as an error of 1' in the angle produces in a distance of 1 mile a difference of 5ft. 8 inches, or nearly 6 feet, but in a distance of 400 roods only an error of 1 foot. If the height of any place has been satisfactorily ascertained by uniform results, then the heights of other objects should be determined from this point, such as the ball on the top of a spire, the position of which has been geometrically fixed, or a chimney or finger post, &c. As the cor¬ rectness of these heights will greatly influence the succeeding work, the observations and calculations should be very carefully made at distances, as a rule, not exceeding 500 roods, and the results obtained, repeatedly checked from other positions before they are made use of. Corrections fo r curvature and refraction and for height of the instrument require to be added to the result (compare § 23#). In determining the height of the ground at any of these stations, the centre horizontal wire should be directed to the body of the assistant at a height corresponding to the height of the telescope (about the middle of his chest), by this means the height of the surface at the station will at 222 APPLICATIONS OF PHOTOGRAPHY. once be observed. Otherwise, in directing the centre cross wire to the surface at the station (which is scarcely ever visible), the height of the instrument always would require to be added. With angles of 5 degrees or more, the “ horizontal ” and “ vertical ” correction requires to be applied, because the staff can no longer be con¬ sidered parallel with the vertical wire. Then the proportion of the apparent distance is to the true distance, as the latter is to the horizontal distance; therefore the apparent distance requires to be multiplied by the co-sine of the vertical angle in order to obtain the true distance. In the tables constructed for topographical surveying, this multi¬ plication is already performed, and the correction for angles and distances can be taken out at sight. Both (horizontal as well as vertical) corrections require always to be applied negatively. For a distance of 200 roods and an angle of 5° the horizontal correction =1*5 roods, and the vertical correction O’7 foot. § XXIV. The horizontal and vertical dimensions of all points, ne- B SSoSS.° f cessary for a true representation of the ground, will be obtained by means of the surveying staff. Not only for the sake of correctness, but also in order to make rapid progress with the work, it is necessary to carefully reconnoitre the ground, and select the stations which require to be fixed^ before sending the assistant away with the staff; by this means a good idea of the ground and position is gained from the very first, and a host of errors and misunderstandings are avoided. Nevertheless, the assistant should be so instructed as to stop with the staff at points of importance without being told to do so. In order to represent the ground correctly, a thorough knowledge of the same is indispensable. The positions and directions of the peaks ridges, hollows, valleys, &c., must therefore be perfectly understood, and then the contour lines and levels are fixed by staff stations, and besides these as many heights are determined as may be necessary for making a correct survey. The experienced surveyor will require many less stations than a beginner; it is recommended, therefore, to the latter to obtain a correct knowledge by measurement, whenever he may be in doubt, and to rectify whatever is necessary by revisiting the ground. On difficult ground it is often requisite, after the staff stations have been plotted, to erect the instrument at the most important of these sta¬ tions for the purpose of filling in the detail. It will be sufficient for this purpose to adjust the instrument by the eye. 223 REPORT ON THE CARTOGRAPHIC § 25. Terminat¬ ing work at a station. § 28. Continuing work on a new station. § 27. Penning in and drawing of field work. The staff-stations should be entered in a field book with sufficient description, as far as required for the work, and the distances, angles, and elevations for the same noted legibly and in a tabular form. Generally at all staff-stations, the height of which is to be determined, the angle of correction should be applied particularly at those points which would be used for extending the work, for example in all extensive level¬ lings or operations in wooded country, &c., where there is no opportunity of testing the correctness to or from standard points. § XXV. After all the points fixed by the staff-stations have been laid down on the plan, and the respective heights added (only 2 decimal fractions required), the features of the country should be inserted, as far as known, with a hard pencil, No. 3 (all straight lines being drawn with a ruler) ; then should follow the filling in of the contour lines, which are required to be indicated at the commencement very lightly with soft, pencil. No. 2, as frequent alterations and rubbing out, which is often necessary, would soil the plan. Before leaving the station, a careful examination should be made* that nothing has been overlooked, and that the drawing is completed; for it frequently occurs that mile-posts, footpaths, cuttings, small cliffs, patches of shrubs, &c., &c., are omitted. § XXVI. If it is not desirable to extend the survey by “back¬ ward intersections,” then the points determined by the staff can be used. (a) .—By setting up the instrument at any one of these stations and adjusting the table, so that it coincides with a trigonometrical or other station. (b) .—By letting the staff remain at some carefully fixed point, and selecting a convenient station within view of the staff, and as a rule, not more than 120-130 roods distant from it. At this latter station the instrument is set up and adjusted by the magnetic needle, and the telescope is so directed that the vertical wire exactly covers the staff, then draw the line of vision on the plan backwards, and fix the station point by the distance which has been observed on the staff by means of the horizontal wires, and note its height. It is desirable to test this position by another trigonometrical point. The remainder of the work is accomplished as mentioned in § 24. The points thus determined by means of the staff can only be considered reliable, if they have been observed and calculated with particular care. § XXVII. It should always be made a rule to complete in the field in pencil on the plan everything which afterwards requires to be shown in Indian ink ; only an inexperienced draughtsman will occasionally feel the 224 APPLICATIONS OF PHOTOGRAPHY. want of space to express everything distinctly, and requires to prepare a sketch on a larger scale ; however, he should endeavour to acquire the necessary distinctness in drawings of this kind. For plantations, mea¬ dows, &c., &c., which will afterwards be colored, each surveyor should express, with a hard pencil within the outline either by conventional signs or writing, the object it represents. Names of locality, plantations, hills, &c., &c., should be inserted in the field book in a special column. § XXVIII. The officer is at liberty to make use of already existing § 2 s. use of maps or plans, but he will be held responsible for the correctness of the prlvate plan8 ' portion which he copies (this refers likewise to the finished reductions which have already been given him by the Survey Director.) This, therefore, necessitates a careful testing of these maps in the field in regard to the completeness of detail as well as the correctness of the distances. After the map has been reduced by the Pantograph to the proper scale on tracing paper, or the finished reduction has been traced on tracing paper, then several of the most prominent and well-defined points, such as cross¬ ings and bifurcation of roads, corners of plantations, &c., &c., should be tested by means of “backward-intersections* J or careful determination with the staff. If it is found that the corresponding points on the reduction are correct and agree with those observed geometrically, the reduction is transferred to the plan by rubbing the outline on the back of the tracing paper with soft lead, No 1. or 2, and then tracing the same with a hard pencil or a tracer made for this purpose ; the outline is thus reproduced on the plan by the soft lead on the back. By transferring the detail in this manner, more or less complete, rapidly to the plan, a number of points are obtained, the height of which can frequently be ascertained without the use of the staff. § XXIX. The greatest care must be taken in surveying the margins § 29. Assimiia- of each section, the assimilation of which should, if possible, be made by gin of plans, both officers together. If this cannot be done, the officer who has finished his margins will send to his neighbour an exact and distinct copy on tracing paper, showing the detail about 1 inch in breadth, to enable the latter to compare it with his own work. It is supposed that each officer will proceed conscientiously and not hide his own errors or those of his neighbour. Any existing errors must be rectified on the spot by both officers themselves. If errors cannot be rectified in this manner, the Director should be communicated with. The necessary comparisons and corrections should always be made by the officer himself in the field and not deferred till his return to Berlin. a 5 225 REPORT ON THE CARTOGRAPHIC In assimilating the sections, great attention should he paid in express¬ ing the different kinds of roads in a uniform manner. § so. Bounda- § XXX. In surveying boundaries of provinces, counties, or parishes, the greatest accuracy is required. Boundaries of communes are not surveyed. Boundary stones or marks, &c., should be carefully fixed, likewise disput¬ ed boundaries. All orders against trespass on private property are annulled by the crown. In order to survey the boundaries, cases of doubt about any county or parish boundary are decided by the distribution of taxes, namely, the field or farm is included in that parish to which it contributes the taxes. Where the boundary is formed by streams or rivers which are shown on the plan by double lines, it should be carefully represented, whether the centre, the right or the left bank of the stream forms the boundary. If a stream, indicated by one line only, should form a boundary, but is included in the province, &c., &c., the character (symbol) for such boundary should be shown outside, but if it be the centre, the symbol should be shown alternately on either side of the stream. When the boundaries are not properly marked and extend over a very large tract of land, it is often desirable to survey first the whole of the surrounding country, and then carefully follow the boundary with the assistance of a reliable guide, and insert it accurately on the plan. All boundaries are to be drawn according to the styles laid down in the specimen sheets, in black ink alone, and so completely, that no doubt may arise as to their direction. § 31 . Survey of § XXXI. In regard to surveys of the fortifications, it should be ob- l'ortifications. i o j served that only an outline is required; therefore the foot of the rampart inside, and the crest of the glacis or counterscarp outside, of the “Corps de la Place,” as well as of detached works, will sufficiently define the boundary of the same. Surveying officers are requested to refrain from any demand for assistance from any of the engineers. In case an officer should require access into any fortified place for the purpose of surveying, he should give the necessary intimation to the Commandant and Engineer officer of the place. § 32 . Completing § XXXII. Everything which can be distinctly expressed on the scale of 1: 25,000 should be shown on the plan, and the military pur¬ pose of such a survey should always be kept in mind; therefore, on ground where evolutions of troops can take place, such features as would prove an obstacle should never be overlooked, for instance precipices, terraces, ravines, &c., &c.; but in a rough country, distant from the main roads, such objects are of less importance. 226 APPLICATIONS OF PHOTOGRAPHY. Unimportant details should be left out, for example, small patches overgrown with grass, or heather on hill sides, nor is any particular care required for a correct outline of small plantations. Fallow fields, temporarily covered with grass, should be considered as arable land. In villages and towns, the principal divisions of gardens should only be shown, besides terraces, walls, conservatories, by which, to a certain extent, the outline and directions of streets is indicated. In every respect the plan should be so executed, that it is possible to recognise objects and features at once. Names should always be written near objects which assist in iden¬ tifying any place, for example, single trees, towers in ruins, old batteries, &c., &c., as they will appear on the plan rather insignificant on account of their size. Small mounds sufficiently conspicuous, which cannot be satisfactorily expressed by contour-lines, should be represented by hachures after Miiffling's system. Peculiarities of the country, such as fields with scattered rocks or boulders, large meadows or heath covered with bushes, or stunted trees, should be expressed by their proper symbols. It should be one of the principal objects of the topographer to show great discrimination in the selection of those portions of the work on which the greatest care should be expended; not alone on account of being useful in continuing the survey, but also as it increases the value of the plan. § XXXIII. Neither of the reductions nor of the plan itself should § 33 - p fi vac y *’ oi surveying du¬ ally copies be retained or given away by the officers, nor is it permitted cuments - that any of these documents should be copied by others. CHAPTER III. Drawing of Plans. & XXXIV. Pine weather should in general be taken advantage of § 34 - General 5 0 remarks and used for field work, and rainy days should be employed for drawing ; but the penning in of the detail as well as contour-lines in Indian ink should keep pace with the survey. In the monthly reports, the total of the surveyed portion should be expressed as “ penned in," only the pen¬ ning in of the work near the margin should be deferred until it agrees in every respect with the plan executed by the surveyor of the adjoining section. 227 REPORT ON THE CARTOGRAPHIC § 35. Penning in contour and intermediate lines. § 36. Terraces and Ravines. § 37. Turnpike and other roads. Without exception, all outlines and contours should be always drawn with a drawing pen. Everything which requires to be drawn in Indian ink should be done during the surveying season, but coloring should be delayed until the arrival of the officer in Berlin; only streams and small water-courses should be shown in blue, and the roads, for the sake of clearness, in brown, yellow, &c., &c. XXXV. Contour lines of 50 feet (50, 100, 200, 250, &c. &c.) are drawn in the strength of the 15 degree lines of the 25,000 scale (see fig- 2, plate XIII), those of 25 feet (25, 75, 125, 175, &c.,) should be drawn in the strength of the 5 degree line. In sections where 12 J feet contour lines occur, they are expressed in long pecked lines, but in the same strength as those of 25 feet. If for a more minute representation of the ground other intermediate lines are requisite, they should be shown in finer pecked-lines than the 25 feet contours. At elevations of 30° or more, the 25 feet contours are not inserted. The intermediate lines are used if a conspicuous elevation occurs be¬ tween two contours, or where the curvature is sharp, in order to indicate clearly the spur and the ravine of the hill, also to indicate smaller hills, ranges, horizontal terraces, &c., &c. The use of intermediate lines should be reserved for such cases where they are really required for a true representation of the ground. The intermediate lines should be shown on the plan in the follow¬ ing manner:—The interval between two ordinary contours has to be divided into three equidistant parts, which can be easily done on the drawing, except where a mound rises only to two such equidistant parts or less; but in all cases where intermediate lines are introduced, always two should be used. § XXXYI. Terraces and ravines should always be shown on the plan, if they are useful in recognising the country or important for military purposes (evolutions, marches, &c.) ; the top of a ravine should be indicated by a connected line. To avoid over-crowding the plan, small rivulets should only be shown by a line of moderate thickness. § XXXYII. (a .)—Turnpike Road ,.—All roads which have been made by the state, county, or a company, &c., in the customary manner, and where a toll is levied, should be shown as turnpike roads. To this class of roads also belong all those (whether tolls are levied on them or not), which have been made by the Royal Forest and Mines 228 APPLICATIONS OP PHOTOGRAPHY. Department or the respective communes and which are kept in repair for an annual payment ( not by hand or statute labor) and are under the inspection of a superintendent of roads. It is irrelevant for the survey as well as drawing, whether the surface of the road is metalled or consists of gravel, &c., &c., if only the foundation is properly constructed, and the surface is capable of bearing the weight of heavy ordnance or wagons in any state of the weather. The conventional symbol for such roads is two double black lines colored carmine. Besides completed turnpike roads, those in course of construction also require to be surveyed, but only such portions as are far enough ad¬ vanced ; indicating that an alteration in the direction is not likely to take place. New projects, although they may have received the sanction of Government, should not be regarded; the same refers likewise to railways. (b.)—Improved Roads.— To this class belong all roads which have a firm surface but as regards breadth, foundation, incline, and water-courses are not constructed according to the approved method, nor are any contributions paid for their being kept in repair, which is performed by statute labor, &c. Also those roads which were originally turnpike roads, but in consequence of change of traffic are at present only partly kept in repair, and not in a condition to carry heavy ordnance and wagons, are designated as “ improved roads.” The symbol for these is 2 black lines, colored minium. (