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(407) 
SOME ASPECTS OF PHOTOGRAMMETRY IN GREAT BRITAIN 
by 
J. A. Eden. 
1. The Photogrammetric Society. 
I am glad to be able to report that we have at last a Photogrammetric 
Society in Great Britain open to any who may care to join. The Society does 
not claim to represent everyone interested in Photogrammetry in the country, 
but it is the only open society in the country, exclusively interested in Photo- 
grammetry, and is to publish a journal which promises to be of a high standard. 
In Britain, publications on this subject have been rather scattered in various 
technical journals so that little may have been widely read particularly by 
photogrammetrists overseas. We hope the new journal will help to make British 
work better known. 
2. Precision Plotting Machines. 
Frequent reference in this paper is made to precision plottng machines. 
This term is intended to describe that group of plotting machines, similar in 
general characteristics to the Wild A5 such as are made by Zeiss, Wild, Poivil- 
hers and Santoni and which are capable of a higher degree of precision than 
many other instruments such as the multiplex. 
There is no intention to imply that the multiplex or any other instrument 
is not capable of the precision for which it is designed. 
3. Tbe General Survey Problem as viewed in Great Britain. 
I believe some of our international friends rather think that because we in 
Britain do not use a very large number of precision plotting machines we are a 
bit slow in the uptake and behind the times. Nothing could be further from the 
truth. 
I should like to outline briefly how, I believe, most of us in Britain view 
the general survey problem. There is, of course no divergence from the view 
that the basis of any survey must be an accurate framework of points over the 
country, and that this framework should then be broken down into smaller 
frameworks as required. The initial framework should be established to the 
greatest possible accuracy since this will form the basis of all surveys of any 
type which may be undertaken in the future. Up to the present, this primary 
framework is necessarily undertaken by ground survey methods. 
Having got the initial framework, the next consideration is to decide the 
scale and accuracy of the detail survey. This must be governed by the social and 
economic requirements which give rise to the need for the mapping. For example 
it is not considered economical or justifiable to map large areas of completely 
undeveloped country such as form the greater part of the British Colonial terri- 
tories, at scales of 1/20,000 or larger. As I see it, the first stage in mapping a 
completely undeveloped country is to prepare a map at a scale of 1/50,000 or 
smaller. These scales necessarily involve a considerable amount of convention- 
alisation. For example, one is not concerned with the widths of roads or the exact 
sizes of the buildings and the accuracy required for more general detail such as 
rivers need be no greater than can be drawn at the scale of the published map.