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stabilization correspondingly minor approximation in direct proportion to the angular 
value of the initial displacement. 
Stabilization tests were also performed starting with gyroscope standing still. As 
was foreseen was noted a medium period of time notably inferior (about 3-330") 
for the stabilization, which demonstrates not only the stabilization process starts from 
the low speeds of rotation, which is evident, but also that the stabilization occurs much 
before the gyroscope has reached the normal rating turns. 
and — Prolonged recording (3 hours) with instrument immobile. — These tests were 
especially conducted to survey the functioning in time of the erection system whose 
duty is that of correcting the displacements ol the rapid rotation axis from the direction 
of the gravitational field, and therefore particularly to timely compensate the cffects cf 
the preccssional. movements. 
The recording has also revealed the trend of these corrections in time. In fact 
there was enccuntered a periodic oscillation of the luminous mark at about a medium 
value (the instrumental zero, with a period cf about three seconds time and medium 
amplitude cf 2-3' cach way. Slight displacements of medium values of this oscillation 
take place but are very rare and it was not possible to ascertain if they respond tc any 
law. They are therefore to be considered accidental and anomalies; during these anom- 
alis maximum | displacements up to 6-7 minutes from the zero were noted 
With the object of making a statistical survey of the displacements, vertical lines 
were traced every 30 mm. in correspondence of which the readings were made, as though 
cach 3c seconds there happened the cpening of the shutter and the exposure of the 
photegram. Of 450 readings there resulted 809/ within 2 minutes and 93°, within 3 
minutes, The distribution of the number cf the indications corresponds with good ap- 
proximation tc the curve of Gauss. 
The results of this group of tests have therefore permitted to establish the regular 
functioning cf the erector system and inasmuch that for two gyroscopes these tests were 
repeated to the end of the complete cycle cf the experiments with the same results, they 
have also proved that the cfficiency of the crector was unvaried after circa 110 hours 
of functioning. 
3rd — Acceleration test. — The apparatus was mounted cn a large bench rotat- 
ing about a vertical axis having a speed that could be regulated in such manner so as 
to cbtain, kecping into account the distance of the gyroscope trom the center of rotation, 
the desired accelerations. The emplacement of the gyrosccpe cn the bench was susceptible 
to be retated go? in such manner that the accelerations were directed along the primary 
axis (lengitudinal accelerations) or along the secondary axis (lateral accelerations). 
All the tests were made by imposing the same accelerations for the same period of 
time, once longitudinally and once laterally, because, given the arrangement of 
the gyroscopes upon the camera (with the primary axes perpendicular to cach other) the 
accelerations, due to the turns that are the strongest, act on one of the gyroscopes, in the 
direction of the primary axis and the cther in the direction of the secondary axis. 
Accelerations variable between o.3 and 0.4 g for a duration cf 70” and go” were 
applied, corresponding to the normal speed of photogrammetrical airplanes tc turns of 
180°, in ratio te 2-3 degrees per second. 
All the tests made have demonstrated that when finishing applying the acceler- 
ation, a residual banking, as was foreseen, given the tendency of the gyroscope of plac- 
Ing itself according to the apparent vertical; there was noted however that while there 
could be foreseen that the influence of the longitudinal acceleration that acts along the