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Experience has shown the necessity to study and experiment with maximum care 
the anti-vibrating suspensions of the camera fitted to this system of recording. 
sth — Tests of variation of the feeding current. — The feeding of the gyroscope 
rctors is made by 36 V. 400 Hertz. This current is supplied by a suitable generator 
that in its turn is fed by continuous current by the normal aircraft battery (24-26 V.). 
Since the current supplied by this battery can for various reasons undergo more or less 
sensible variations their influence upon the efficiency of the gyrescope was studied. The 
variations in the feeding tension of the generator cause, among other things, à change 
in the period of the A.C. current and therefore in the rotation speed of the rotor. 
Tess were made at 22, 24, 26, 28, 3o V. D.C. 
It was not possible to find appreciable differences in the readings of the numerous 
tests made either in regard to absolute indication or concerning the stability, that is 
to say, maximum displacements in respect to the average. 
These tests confirm the proof already obtained from the stabilization tests, that 
is to say that also below the normal rating speed the functicning of the gyroscope 
and the erector develops normally. They have also allowed to establish tolerances 
sufficiently ample (+ 10 97) in the feeding voltage of the generator of the alternating 
current for the gyroscope. 
6th — Tests of variations in temperature. — Having placed the apparatus in a 
thermostatic device, recording tests were made at temperatures variable between —15° C. 
and +50° C. In the tests at low temperature (from + 10° to —I0°) very regular functioning 
of the gyroscope as well as the erector was found; at high temperature there was found 
a displacement of the medium line of oscillations of abcut 6 between ro? C. and 20 
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while between 30° C. and 50° C. the medium line returned to the initial position; at 
high temperatures the recording shows a greater regularity. These tests demonstrate that, 
inside the limits which are normally assured by thermostats that are situated in the cone, 
the oscillation of the temperature dces not cause any detriment whatever to the functioning 
of the gyroscopes. 
"th — Lateral and longitudinal tilting tests, — Having freed the gyroscopic unit 
from the recording unit, the gyroscopic unit was mounted on an orientable bench, 
with the rotation axis parallel to the primary axis and almost coincident with it, while 
the recording unit was mounted at the outside. There was then imposed to the gyro- 
scope tilts of 3°, 6°, and 0°, in one sense and in the opposite, subscquently periodic 
oscillations were imposed with a period of 5 and of 3 seconds for each one of the 
above said angles, 
All the tests of tilting and lateral oscillation (that is to say about the primary 
axis) revealed a most regular behaviour both by the gyroscope as well as by the 
erector, Only in oscillations of + ¢° with a periol of 3" there some times are 
manifested slight disturbances of 6-8 minutes and an emphasis of the periodic 
oscillations due to the erector. 
The tests were then again repeated rotating the gyroscope by 9o? so that the 
rotating axis of the bench resulted parallel to the secondary axis. All the recordings 
resulted regular, also in this case with an emphasis of the perturbations in the oscil- 
lations of great amplitude and frequency, only one gyroscope that had in the preceding 
tests given very good results manifested notable bankings in the primary axis (up 
0 1520 minutes). When once the suspensions of the secondary axis were adjusted 
and tests repeated these tests were satisfactory. 
This test has confirmed the necessity, which is however evident, of checking