(VE) Belongs to the Perspective 294
V. The Perspectometer as Used by Capt. E. Deville 294
VI. The Perspectograph Devised by H. Ritter 208
Use of the Perspectograph 301
VII. Prof. G. Hauck's Trikolograph and its Use in Iconometric Plotting. 302
VIII. The Carl Zeiss Stereoscopic Telemeter and the Stereocomparator,
Including the Sterecphotogrammetric Surveying Method De-
vised by Dr. C. Pulfrich , 308
A. The Stereoscopic Telemeter, or Range-finder 309
B. The Stereocomparator and the Stereophotogrammetric Sur-
veying Method 318
PHOTOGRAPHIC OPERATIONS IN THE FIELD.
I. General Remarks on the Exposure of a Photographic Dry Plate . . 335
II. Orthochromatic Dry Plates and Ray-filters 339
A. Color-screens, or Ray-filters 340
B. Halation 342
III. Comparative Light Values and Exposures 343
Test Exposures and Trial Plates 346
IV. Development of Orthochromatic Dry Plates 348
A. Water and Water Tests 352
B. Developers 353
1. Developing with Ferrous Oxalate 353
a. Restraining the Ferrous Oxalate Development .... 356
b. Accelerating the Ferrous Oxalate Development. . . 357
2. Pyro Developer 358
3. Metol Developer 359
4. Metol-bicarbonate Developer 360
5. Hydrochinon Developer 361
6. Metol-hydrochinon Developer 363
7. Bromo-hydrochinon Developer 364
8. Eikonogen Developer 364
9. "Eiko-cum -hydro" Developer 365
10. Amidol Developer 366
C. Fixing the Negative 366
1. Tests for Presence of Hyposulphite of Soda 368
2. Drying the Finished Negative 369
3. Intensification of a Negative with the Aid of Metallic
4. Intensification with Silver Cyanide 370
5. Prof. R. E. Liesegang's Intensifier 371
6. Intensifying Negatives without the Use of Metallic Salts . 372
7. Reducing the Density of a Negative 373
8. Cooling Solutions 374
D. Negative Varnish 375
V. Photographic Printing 376
A. Toning Photographic Prints ' . . 379
B. Fixing Photographic Prints 381
C. Formulas for Plain Toning-baths 382
D. Combined Toning- and Fixing-baths 383
CONCLUSION AND REMARKS ON THE PRECISION OF THE "POLAR ICONOMETRIC
METHOD" AND GENERAL REMARKS ON TELEPHOTOGRAPHY.
I. General Remarks on Phototopography 387
H. Precision of the " Polar-iconometric " Method 391
in. General Remarks on Telephotography or Long-distance Pho-
PHOTOTOPOGRAPHIC METHODS AND
TOPOGRAPHY is that branch of surveying which pictures
sections of the earth's surface, in reduced scale, as a horizontal
projection, showing the relative positions of points of the ter-
rene in both the horizontal and vertical sense. Under topog-
raphy, in the closer sense, we generally understand the represen-
tation of the terrene in the form of charts, drawn to the scales
of i : 5000 to i : i ooooo, showing not only the relative positions
of characteristic points of the earth's surface, but also clearly
delineating all natural and cultural details. Topographic charts
on scales smaller than i : i ooooo partake of a geographic char-
acter, while surveys on scales larger than i : 5000 are generally
made for special technical purposes.
The works of filling in the details, topographic surveying
in the closer sense, may be accomplished by various methods,
differing in the matter of cost, time, and attainable accuracy.
One may be employed with advantage for one class of work r
while another may be preferable for another class, another locality,
or, to meet different conditions. The method best adapted to
any particular region should be employed to obtain the best
2 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.
The more important methods with their instrumental out-
First The direct plotting to scale, in the field, of all fea-
tures that are to be shown on the chart,
A with a plane table and telemeter or stadia rods;
B with a tachygraphometer and stadia rods;
C with either of these instruments, but with a leveling
instrument in addition, for locating the horizontal
D using an aneroid barometer in place of the level.
Second The compilation of all available data (cadastral
surveys, public land, and county surveys, railroad
and canal surveys, etc.), giving principally the hori-
zontal distances, a supplementary survey being made
to furnish the missing data, which in this case are
principally elevations. They may be supplied by
trigonometric or spirit leveling, by interpolation and
Third The records of the survey may be obtained in the
shape of field notes and sketches (" tachymetry "),
the map being produced by plotting the recorded
data in the office.
A with a surveyor's compass and steel tape the rela-
tive positions of characteristic points may be located
in the horizontal sense, while their relative eleva-
tions may be obtained by means of a level, minor
details being largely sketched;
B with a transit and steel tape points are located, both
geographically and hypsometrically, minor details
C with a transit and stadia rods;
D with a tachymeter and stadia rods, elevations being
E adding a leveling instrument for locating horizontal
F using a specially constructed aneroid barometer
(" Goldschmidt's "), in place of the level for locating
and tracing the contours in the field.
Fourth The field records for developing the terrene are
represented by photographic negatives, taken under
special conditions from stations of known positions
A with a camera or phototheodolite, using telemeters
or other distance measures for obtaining the lengths
of base lines and a barometer for ascertaining the
elevations of tertiary points;
B with a surveying camera, separate transit, telemeters,
C with a photographic plane table and distance-meas-
uring alidade, using a barometer for obtaining the
elevations of detached camera stations;
D with a surveying camera, separate plane table, dis-
tance measure, and aneroid barometer;
E with a specially constructed phototheodolite, the
iconometric plotting being done with the Zeiss stereo-
F with cameras designed to be used attached to kites,
to free or to captive balloons.
Minute and detailed methods with ensuing accurate results
should be applied to the surveys of cities and all densely settled
regions, to the coastal belts, large river valleys, and lakes, par-
ticularly when navigable, and this work should be plotted on a
Arid, barren, and mountainous regions as well as prairies
and swamp lands, when sparsely settled, should be generalized
in their cartographic representations and they should be plotted
on a small scale.
In exemplification of the preceding suggestions we may
refer to the new topographic survey of Italy, where Paganini's
results not only fully proved the efficiency of photography applied
4 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.
to surveys of alpine regions (plotted in 1:25000 and 1:50000),
but also led to the adoption of the phototheodolite as an auxiliary
instrument to the plane table. The latter was used for mapping
the areas below 2000 m. in altitude, while the phototheodolite
was depended on to delineate the terrene lying above that altitude.
After the area which is to be surveyed has been covered with
a net of triangles and polygons it will have been provided with a
framework of lines of known lengths and directions (being in
itself a skeleton survey of the country), and after the natural
details and artificial features have been filled in, by one of the
numerous topographic methods with more or less details and
accuracy, we will have a topographic survey of the area of more
or less precision.
The number of so-called control points for a given area,
determined in elevation and geographical position during a
topographic survey, should be increased in the same ratio as
the degree of accuracy, required for the survey, and also as the
amount of details, conditioned by the scale of the survey, may be
Photography has been extensively applied to surveys of rugged
mountain regions in Italy, Austria, Russia, Canada, and Alaska
with great success. The phototopographic method, originally
devised by Colonel Laussedat, found its first application in France
and in Germany. In its early stages it was practiced exclusively
under governmental and military auspices, being primarily used
for so-called secret and military surveys. Lately, however,
phototopography has found a wider and more general applica-
tion also in France and Germany.
More recently photographic surveys have been executed in
Greece, Spain, Portugal, Norway, Belgium, Mexico, Chile, Peru,
Brazil, Argentine Republic, Switzerland, Australia, England,
Africa, and more recently still in the United States, although
Lieut. Henry A. Reed has, for several years past, taught photo-
graphic surveying, theoretically and practically, at the U. S.
Military Academy at West Point.
SHORT REVIEW OF EXECUTED PHOTOGRAPHIC SURVEYS
AND LISTS OF THE MORE IMPORTANT PUBLICATIONS
ON PHOTOGRAMMETRY AND PHOTOTOPO GRAPH Y.
I. Photographic Surveying in France.
Practical results from the early application of photography
to surveying failed to materialize for some time, partly owing to
the slowness and uncertainty of the old photographic process, and
partly due to the greatly increased efficiency of surveying instru-
ments and methods in general.
The chances of utilizing landscape perspectives for a geo-
metrically true representation of the terrene in horizontal plan
became realized by the combination of surveying instruments
with the modem camera (with the reliable, uniform, and quick
dry-plate process). Of course, it is not necessary to merge the
camera and the geodetic instrument into a single apparatus.
For facilitating transportation and for other reasons they are
frequently used separately over the same station.
The theoretical principles upon which photogrammetric
methods are primarily based were known to J. H. Lambert (of
Zurich), who published a work on perspective in 1759, in which
reference is made to those identical principles. Still, Lambert's
suggestions were neither followed nor were his theories given a
practical application in this respect, until the well-known savant
and hydrographer Beautemps-Beaupre, while on a scientific expe-
dition, in 1791 to 1793, made a series of free-hand sketches of the
regions skirting the shores of Van Diemansland (Tasmania) and
of Santa Cruz Island. After his return to France he attempted
6 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.
the first practical application of Lambert's theory by constructing
topographic reconnaissance maps of the coastal regions just
referred to, based upon the outline sketches of the terrene.
Beautemps-Beaupre subsequently made frequent reference to
the feasibility of his cartographic methods, recommending them
particularly to explorers. Little or nothing, however, was under-
taken by others toward improving Beautemps-Beaupre's new
cartographic method, and it had practically fallen into oblivion
when Arago, in 1839, called attention to the possibilities of
photography when utilized in this connection.
Beautemps-Beaupre's suggestions probably met with so little
favor because it is not easy to make free-hand sketches of land-
scapes geometrically accurate enough to be used iconometrically in
place of the landscapes. Iconometry as applied to topographic
plotting rests upon the same principles as the plane-table method
of determining points by the intersections of lines of direction,
drawn to such points from known stations, only in iconometry
such lines are graphically deduced from the photographic per-
spectives and are drawn in the office.
Apparently Capt. Leblanc, of the French Ge*nie Corps, made
the only applications of Beautemps-Beaupre's method, in ante-
cedence of the year 1849, principally in connection with military
Col. A. Laussedat had taken up the study of iconometric
map-plotting in 1850. In the early part of his investigations
he utilized a "camera clara" (invented by Wollaston in 1804)
for obtaining the necessary perspectives of the terrene, tracing
their outlines by hand. In 1852, however, he replaced that
instrument by the "camera obscura" (invented by Dom Panunce,
or by some attributed to G. della Porta). Laussedat's camera
obscura was modelled after Niepce's, but it was supplied with
special surveying devices.
Subsequently as Chef du Genie Corps, Laussedat executed
numerous experimental surveys, improving the surveying camera
and elaborating the methods. In 1858 he obtained a Bertaud
PHOTOGRAPHIC SURVEYING IN FRANCE. 7
lens, which was practically free from aberration and which he
used for the new phototheodolite made by Brunner in Paris.
In 1859 Laussedat felt justified, by the good results he had
obtained with this improved phototheodolite, to announce the
successful application of photography to surveying to the Academy
of Sciences in Paris. After a critical examination of Laussedat's
methods and results, by Daussy and Laugier, these two members
of the Academy approved and endorsed his methods. Laussedat
also made a few topographic maps with the aid of balloon-
photography, but soon returned to the exclusive use of the
At the exposition of 1867, in Paris, Laussedat exhibited the
first known phototheodolite and some map specimens, based
upon photographic surveys, among others a plan of Paris (scale
i : 6666) which compared very favorably with one that Emmery
had made in 1839 by means of instrumental surveys. The
survey for the phototopographic map of Faverges in Savoy,
scale 1:5000, was executed in 1867 by Capt. Javary and Lieut.
Garibaldy, of the Genie Corps, under Col. Laussedat's direction,
and it was based on 120 photographs. It covered an area of
about three square miles and the topography was controlled by
about 5600 points that had been identified on the pictures and
which were plotted iconometrically on the chart.
Col. Laussedat's work in this field has been so complete that
the guiding principles which he first laid down and subsequently
elaborated by numerous practical applications are still in use,
and his interest in this work continues unabated to this day.
From 1851 to 1871 Col. Laussedat and his associates in this
work were frequently called away from the pursuance of photo-
topographic surveys, having other duties assigned them, and we
find that Laussedat's surveying methods did not become generally
known in France, and it was left to scientists and engineers of
other countries (Germany and Austria) to popularize this survey-
ing method and extend its application to various branches of the
8 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.
In 1858 Chevallier had an instrument patented under the
name " planchette photographique " which soon found much
favor, especially among members of the Genie Corps. This
photographic plane table is described by Alophe (" Le passe,
le present et 1'avenir de la photographic," Paris, 1861), by
d'Abbadie (" Bulletin de la Societe de Geographic de Paris,"
1862), by Pate (" Application de la photographic a la topographic
militaire," Paris, 1866), by Col. A. Laussedat (" Recherches
sur les Instruments, les Methodes et le Dessin topographiques,"
Paris, 1898), and others. It was manufactured by Dubosque,
in Paris, and used by Wiganowsky, Pate, and A. Jouart.
Martens, in Paris, was probably the first to devise a " pano-
ramic camera " (1847), i n which he used a cylindrically bent
Inclined plates for phototopography were also used at an early
date in France, notably by Th. Pujo and T. Fourcade, who
published their methods, under the title " Goniometrie Photo-
graphique," in Les Mondes, No. 4, 1865.
France had an interesting exhibit at the World's Columbian
Exposition in Chicago, 1893, showing photographic surveying
instruments and map specimens, in illustration of topographic
and astronomical results, gained chiefly under the direction
of Col. A. Laussedat and taken from the collections of the Con-
servatoire National des Arts et Metiers, Paris, of which insti-
tution Col. Laussedat is now director.
In recent years balloon surveying has been resumed in France
under the auspices of the Ministry of War, the camera being
used in connection with both the free and captive balloon. Bal-
loon surveying had been rather neglected, notwithstanding the
good results which had been obtained in the early stages of photo-
graphic surveying in Paris by Col. Laussedat and Nadar (1866).
Long-distance photography (" telephotography ") seems to
have been first studied in France by Lacombe and Matthieu.
A resume of their results has been embodied in an official report
to the French Government in 1887 by Commandant Fribourg,
PHOTOGRAPHIC SURVEYING IN FRANCE. 9
recommending the adoption of telephotography as a reconnoiter-
ing method in the Genie Corps.
Guillemont and Jarret followed in the lines laid down by
Lacombe and Matthieu, but little reached the general public
regarding the practical results obtained by this method in France.
Still, it is now well known that the French officers stationed
at Grenoble have obtained excellent results in telephotography
as applied to military reconnaissance, showing the operations and
the disposition of troops in the field, depicting the effects of
cannon-shots upon bombarded fortifications, etc. The tele-
photographic negatives obtained at Grenoble clearly define
objects at distances from 2 to 6 km. The French telephoto-
graphic cameras are mostly made by Hondaide and Derogy in
In 1893 H. Vallot commenced the mapping of the. Mont
Blanc mountain group, and its immediate vicinity. He is assisted
in this work by J. Vallot, who, in 1890, founded a meteorological
observatory on Mont Blanc. This map is being drawn in
i : 20000 scale and the greater part of the topography is based
Other French publications on photography applied to sur-
veying, besides those already mentioned in the preceding para-
graphs, are as follows:
A. LAUSSEDAT. "Memoire sur PEmploie de la Chambre Claire dans les
Reconnaissances topographiques." Memorial de 1'Officier du Genie,
Xo. 16, 1854.
A. LAUSSEDAT. "Analyse d'un Memoire sur PEmploie de la Photographie
dans le Leve des Plans. "Comptes rendus de 1' Academic des Sciences,
A. LAUSSEDAT. "Memoire sur PEmploie de la Photographie dans le Lev
des Plans," Memorial de POfficier du Genie, Nov. 17, 1864.
A. LAUSSEDAT. "Historique de P Application de la Photographie au Lever
des Plans," "Conference faite au Congres de PAssociation Francaise
pour PAvancement des Sciences," Septr. 17, 1892. Comptes rendus du
Congres de Pau et Revue scientifique de 1892.
10 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.
A. LAUSSEDAT. "L'IconometrieetlaMetrophotographie." Conference faite
au Conservatoire des Arts et Metiers, deuxieme, Serie, II, III, IV, 1892-93.
A. LAUSSEDAT. "Exposition Universelle de Chicago, 1893, Section Fran-
caise, Instruments et Appareils Iconometriques et Metrophotographiques,"
des Collections du Conservatoire National des Arts et Metiers. Paris,
1893, Imprimerie Nationale-.
A. LAUSSEDAT. "Les Applications de la Perspective au Lever des Plans,"
Annales du Conservatoire des Arts et Metiers. Paris, 1893-94.
A. LAUSSEDAT. "Reconnaissance faite a 1'Aide de la Photographie, pour la
Delimitation de la Frontiere entre 1' Alaska et la Colombie Britanique."
Comptes rendus de 1' Academic des Sciences, Paris, 1894.
A. LAUSSEDAT. " Conference de Metrophotographie," Instructions et Ex-
plications sommaires a 1'Emploie de la Photographie dans les Recon-
naissances topographiques faites par les Voyageurs," Revue scientifique,
No. 26 I, No. 23 II. Paris, 1894.
A. LAUSSEDAT. "Recherches sur les Instruments, les Methodes et le Dessin
topographiques" (Tome II). Paris, 1903.
A. LAUSSEDAT. "De PEmploi du Stereoscope en Topographic et en Astro-
nomic." Comptes rendus des Seances de 1' Academic des Sciences,
CXXXVI, p. 22-28, 1903.
A. LAUSSEDAT. "Sur un Moyen rapide d'obtenir le Plan d'un Terrain
en Pays de plaines, d'apres une Vue photographique prise en Ballon."
Comptes rendus, 137 Vol., pp. 24-30. Paris, 1903.
E. PATE. "Applications de la Photographie a la Topographic militaire."
LAUGIER &DAUSSY. "Rapport sur IcMemoiredeM.Laussedat." Comptes
rendus de 1' Academic des Sciences, 1860.
A. JOUART. "Applications de la Photographie au Lever militaire." Paris,
JAVARY. "Le Memoire sur les Applications de la Photographie aux Arts
militaires." Memorial de 1'Officier du Genie. Paris, No. 22, 1874.
Dr. G. LE BON. "Les Civilizations de ITnde." Firmin, Didot et Cie.
Dr. G. LE BON. "Les Levers photographiques et la Photographie en
Voyage." Gautier Villars et Fils. Paris, 1889.
Partie I: "Application de la Photographie a l'6tude geometrique des
monuments et a la Topographic."
Partie II: "Operations complementaires des Levers topographiques."
P. MOESSARD. "Le Cylindrographe, Appareil panoramique."
Partie II: "Le Cylindrographe topographique." Gauthier, Villars et
Fils. Paris, 1889.
P. MOESSARD. "Les Panoramas photographiques et les Appareils pano-
PHOTOGRAPHIC SURVEYING IN FRANCE. n
ramiques." Bulletin de la Societe Franchise de Photographic, deuxieme
Serie, Tome IX, 1893.
E. MONET. "Principes fondamentaux de la Photogrammetrie." Societe
d'Editions scientifiques. Paris, 1893.
E. MONET. "Application de la Photographic a la Topographic." Bulletin
d'Aout, 1894, de la Societe des Ingenieurs Civils de France.
J. GIRARD. "La Photographic et ses Applications aux Etudes geographiques."
ALFRED HANOT. "La Photographic dans les Armees." Paris, 1875.
FL. DUMAS. "De la Photographic et ses Applications aux Besoins de
1'Armee." Paris, 1872.
J. BORNECQUE. "La Photographic appliquee au Lever des Plans." Paris, 1886.
A. DE LA FUYE. "La Photographic a grande Distance." Revue du Cercle
A. DE LA FUYE. "M&noire sur PEmploi des Appareils photographiques
pour les Observations a grande et a petite Distances." Autographic a
l'6cole de Genie de Grenoble, 1891.
Capt. E. DEVTLLE. "Lever topographique des Montagnes Rocheuses, exe-
cute par la Photographic." Bulletin de la Societe francaise de Photo-
graphic, deuxieme Serie, 1893.
R. COLSON. "La Photographic sans Objective." Gauthier, Villars et Fils.
ARTHUR BATUT. tc La Photographic aerienne par Cerf volant." Gauthier,
Villars et Fils. Paris, 1890.
Le Col. BERTHAUD, Chef de la Section topographique. "La Carte de
France (1750-1898). Etude historique," 2 Vol., Imprimerie du Service
geographique de 1'Armee, 1899.
Le Capt. du Genie BOUTTREAUX. "Me*moire sur la Telephotographie,"
Revue du Genie, Sept., 1897.
L. CAZES. "Stereoscopic de Precision. Theorie et Pratique," Librairie
Michelet, Ph. Pellier, Editeur, 1895.
E. DOUGLAS-ARCHIBALD. "Les Cerfs volants militaires." Librairie Uni-
verselle. Paris, 1888.
F. DROUTN. "Le Stereoscope et la Photographic ste"rebscopique." Ch.
Mendel. Paris, 1894.
Le Capt. HOUDAILLE. "Sur une Me*thode d'Essai scientifique et pratique
des Objectifs photographiques " Gauthier, Villars et Fils. Paris, 1894.
J. LE CORNU. "Les Cerfs volants." Monie et Cie. Paris, 1902.
MAX LOEHR. "Sur la Determination des Me*sures du Teleobjectif." Bulle-
tin de la Societe francaise de Photographic, 1902.
H. ROUSSON. "Instructions sur le Photogrammetre de PExplorateur."
Imprimerie Dubos. Paris, 1900.
12 PHOTOTOPOGRAPHIC METHODS AND INSTRUMENTS.
GASTON TISSANDIER. "La Photographic en Ballon " Gauthier, Villars et
Fils. Paris, 1886.
A. VAUTIER-DUFOUR. "Sur la Telephotographie." Bull, de la Soc. Vaudoise
des Sciences naturelles, No. 143. Corbaz et Cie. Lausanne, 1902
CH. VON ZIEGLER. "Le Perspecteur mechanique." Fr. Weber. Geneve
E. WALLON. "Traite elementaire de 1'Objectif photographique." Gauthier,
Villars et Fils. Paris, 1891.
E. WALLON. "Choix et Usage des Objectifs photographiques." Gauthier,
Villars et Fils. Paris.
EMILE WENZ. "Resume historique de 1'Invention de la Photographic aeiienne
par Cerfs volants." Bull, de la Soc. francaise de Photographic. Avril,
II. Photographic Surveying in Germany.
Col. Laussedat's photographic surveying methods soon found
admirers and earnest students in Germany and Dr. A. Meyden-
baur became an early exponent of this method. Some writers
even claim that, in 1858, while Meydenbaur was engaged with