A Recent Trip into the Chumbi Valley, Tibet Author(s): Walter Buchanan Source: The Geographical Journal, Vol. 53, No. 6 (Jun., 1919), pp. 403-410 Published by: geographicalj Stable URL: http://www.jstor.org/stable/1780416 Accessed: 04-05-2016 13:40 UTC Your use of the JSTOR archive indicates your acceptance of the Terms & Conditions of Use, available at http://about.jstor.org/terms JSTOR is a not-for-profit service that helps scholars, researchers, and students discover, use, and build upon a wide range of content in a trusted digital archive. We use information technology and tools to increase productivity and facilitate new forms of scholarship. For more information about JSTOR, please contact
[email protected]. The Royal Geographical Society (with the Institute of British Geographers), Wiley are collaborating with JSTOR to digitize, preserve and extend access to The Geographical Journal This content downloaded from 131.91.169.193 on Wed, 04 May 2016 13:40:49 UTC All use subject to http://about.jstor.org/terms A RECENT TRIP INTO THE CHUMBI VALLEY, TIBET 403 projection you must know the focal length of the lens used in taking the aero? plane photograph, and you must also understand fairly thoroughly the principles of perspective, and so on, on which it is based. So that in the hands of anybody who does not know exactly what he is doing it may go wrong. With the enlarging camera apparatus I do not think you can make a mistake ; provided you get your four points to agree exactly, you have a correct projection, and your print will be absolutely correct.