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HINTS TO TRAVELLERS. 
methods, which are mostly subsidiary, and often not so accurate, or 
simple, or generally applicable as the method described above. For the 
purposes of a traveller, as before explained, it is not absolutely necessary 
that he should be proficient in the arb of map-making from pictures. 
His attention should be mainly concentrated on the selection of suitable 
stations in the field, and on obtaining sufficient good cross views from 
those stations. The topographical construction work can then be carried 
out by experienced men at home. 
The foregoing description sufficiently describes the general method 
adopted, which is really a kind of plane-tabling upon the pictures in 
place of the actual landscape views. Any reader who wishes to study 
the subject more deeply from a theoretical or practical point of view can 
in these days easily obtain very full information from a study of modern 
literature on the subject. The most complete special treatise at the 
present time in the English language is given in the U. S. Coast and 
Geodetic Survey Report for 1897 (Appendix No. 10), entitled “ Photo- 
topographic Methods and Instruments/’ by J. A. Flemer. There is also 
a book entitled ‘ Photographic Surveying/ by Capt. E. Deville, Surveyor- 
General of Canada, published at the Government Printing Bureau, 
Ottawa, Canada, in addition to which there are many other publications 
in French, German, Italian and Spanish. A full detailed description 
of the Bridges Lee photo-theodolite, and of the newest improvements 
for securing automatic records of important data on the face of each 
picture, has been written by the inventor, from whom any further 
information can be obtained. 
Surveying a Country and fixing positions by means of Latitudes 
and Azimuths. 
This system of surveying can be used with advantage in a country the 
surface of which is so varied as to present several prominent and distant- 
objects. 
In order to use this method the traveller must first prepare a Mercator's 
projection that will include the area he intends to map. The reason for 
making choice of Mercator’s projection is, that a line of bearing drawn on 
