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The existence of the SHAR effect in observations of spinning
pendulous gyroscopes generally, was confirmed by limited tests
carried out on both a Wild T16 theodolite (No. 102025) and GAKi
attachment (No. 2890) and a Fennel KTi (single second) gy-
rotheodolite (No. 108051). The predicted "high-low" range mani
fested itself in observations taken with both these instruments
and served to confirm the secondary patterns obtained with
GAKi (No. 3139).
Conclusions
The experimental work described above has, in addition to
verifying previous beliefs and contentions regarding accuracies
of gyroscopes and observing techniques, thrown new light on the
relatively unknown anomalous behaviour of the spinning gyroscope.
Results presented in this paper reflect azimuth accuracies
for the GAK1/T2 equipment well above the manufacturer's claim.
In this respect, forward and reverse azimuth determinations along
a known test line nine kilometres in length were in agreement to
within approximately five seconds of arc. Periodic redeterminations
of the instrumental calibration constant will help to ensure peak-
performance of the gyrotheodolite.
Comparisons between the reversal point and transit field pro
cedures appear to substantiate the maker's claims of accuracy
parity of the two methods for determining 0O. The transit method,
whilst being less tiring to the observer, does nonetheless require a
stop watch with trailing second hand as an essential extra. In
the authors' opinion, when five or six reversal points (transits)
are to be observed, the choice is an arbitrary one, but with obser
vations being carried out over a longer period of time, the less
tiresome procedure is recommended. When the reversal point
method is applied, and to a certain extent this applies to the transit
method as well, the SHAR effect should be used as a criterion for
judging the completeness of the set of observations and hence
whether the stability line has been successfully captured; as has
been described in the body of the paper.
A cknowledgements
The authors are particularly grateful to Messrs. Wild of South
Africa, Ltd., for their kindness in providing the test equipment.
Especial thanks are also due to Mr. A. Raffle for his initiation
of the loan and assistance with some of the observations, and to
Mr. B. Schneider for carrying out the specified modifications to
the T2 theodolite.
Mr. P. R. Janisch of the Transvaal and Orange Free State
Chamber of Mines Research Laboratories is also thanked for making
the Fennel KTi gyrotheodolite available to the authors for com
parison purposes.
