SETTING UP OF AN EXPERIMENTAL POLYGON IN ITALY, ECC. 
15 
It can be seen that for some strips photographing operations were effected 
about two months after the operations for targeting points had been completed. 
Many of them had even been targeted some three or four months before the time 
when the flight was effected. 
The planes used were U. C. 45 Beechcraft, planes of not too great a power 
which, having to fly at heights which were pretty near the limit of their possibil 
ities and with very strong winds causing some descending currents, particulary in 
the southern part of the Tuscan-Aemilian Appennine, sometimes did not succeed 
in keeping up their resistance speed. Sometimes it did even happen that they had 
to interrupt their flight and return to their base. 
Due to these bad flight conditions, also the observer and the photographers 
met with difficulties above normal, and did not always succeed in obtaining the 
required longitudinal overlap ; also the drift angle resulted particularly great in 
some strips. 
Photographs were taken with a mod. VI Galileo-Santoni camera, using a Su 
per XX Aerographic Kodak film and a DK 50 Kodak development. 
6) Results achieved. 
The negatives obtained were duly printed on paper and a preliminary exami 
nation was carried out to check whether the requirements laid down had been ac 
tually obtained. The examination consisted of checking the longitudinal and trans 
verse overlaps and locating the markings on the points determined. 
The examination of overlaps is summed up in table n° 2 : for each strip we 
have written down, in this order, the following quantities : 
— average longitudinal overlap ; 
— average longitudinal overlap between photographs of even numbers ; 
— average longitudinal overlap between photographs of odd numbers ; 
— minimum longitudinal overlap between photographs of even numbers or 
of odd numbers. 
The side overlap achieved everywhere exceeds 15 %. The table clearly shows 
that for some strips it is impossible to derive two independent strips made of al 
ternate photographs, as the minimum overlap required is not attained : on the 
other hand it would be very costly to effect the bridging of all photographs of the 
strip, with overlaps of more than 75'% ; the base, however, should be too small. 
The examination of the numerical consistency of markings photographed has 
shown that in the high flight only 65,6 % of the markings is recognizable on the 
photographs, whereas the percentage in the low flight is 74,9 %. The points lost 
appear to be located mostly in the north-west, north-east and south-east parts of 
the polygon. 
The above mentioned figures must be'Taken as purely indicative, because some 
known points were, for instance, recognised in the photographs belonging to one