■nHBKi 
10 INAUGURAL PLENARY SESSION 
character are greatly assisted by the measurements which it is now possible to make 
from air photographs. Photogrammetry is now being applied, 1 am told, to medical 
research; for example, in measuring the growth rate of tumours. In medical practice 
too, photogrammetric techniques have been used to give some knowledge of the third 
dimension in X-ray photography. Then this technique has proved of the greatest value 
and technical aid to archaeology, in that any sites and features which appear in the 
aerial photograph can be adequately located on a map prior to their examination in 
the field. I am told that this is constantly happening in the 6" re-survey, which the 
Ordnance Survey of this country is now engaged upon in Scotland; and, of course, it 
greatly increases speed and accuracy of the work. 
All these recent developments indicate the possibility of the extension of photo 
grammetry to many other spheres. You will understand, therefore, why the Department 
of Her Majesty’s Government concerned with these things is supporting this Congress 
and is hoping to take an active part in the technical sessions during the Congress. 
Of course, it is the Ordnance Survey for which my Ministry is responsible, and 
that organisation, as you know, is devoted to the mapping of Great Britain and has 
been in existence for nearly 170 years. Although the mapping of this country had 
reached an advanced stage by the time that photogrammetry was introduced, it has 
been found in recent years very possible and desirable to use its techniques to an in 
creasing extent. Photogrammetry is making a most valuable contribution to the task, if 
one may particularise, of re-surveying the larger towns of this country, in which so much 
reconstruction has been done since the war and in which so much still remains to be 
done. 
Perhaps, however, the greatest use made of photogrammetry by a Government 
Department in this country since the war has been made by the Directorate of Over 
seas Surveys which, thanks entirely to its use of air survey methods, has been able to 
map literally thousands of square miles of our overseas territories in the last twelve 
years. The importance of that needs no stressing from me. 
As in other countries, British commercial air survey firms have played an im 
portant part in helping to provide much needed maps and plans for the advancement of 
photogrammetric knowledge in this country. 
I understand that for this Congress some new features have been introduced. 
Following resolutions passed at your last Congress, your various Commissions proposed 
to devote part of their technical sessions to specially invited papers which have, as far 
as possible, been distributed to you in advance. This is to ensure that the limited time 
available in these sessions will be used to the best advantage without, of course, curtail 
ing opportunities for full discussion of the papers. 
As at former Congresses, an exhibition of the latest photogrammetric equipment 
has been arranged, and this exhibition I am glad and interested to see will be opened 
by Lord Brabazon, one of this country’s great pioneers of the air. 
The organisers of the Congress have asked me to say that they are particularly 
grateful to the large number of firms from far and wide who have contributed towards 
making this such a valuable and comprehensive exhibition. In addition, exhibitions 
covering both the historical and educational aspects of photogrammetry have been 
introduced for the first time, and we hope that these will materially add to the interest 
of the Congress as a whole. We are very grateful to the many organisations who have 
sent contributions to these exhibitions. 
In welcoming you to this Congress, I will only add my sincere hope that during 
your visit — and I am referring to the overseas Delegates in particular — you will see 
something of our country and that the weather will be reasonably fine for you to do so 
in comfort; I cannot be sure about that! I understand, in fact, that a great number of 
technical visits, both during and after the Congress, have been arranged so as to provide