1921-22.] Gyroscope and “Vertical” Problem on Aircraft. 257 
XVIII. — On the Application of the Gyroscope to the Solution of the 
Vertical” Problem on Aircraft). Parti. By James Gordon 
Gray, D.Sc., Cargill Professor of Applied Physics in the University 
of Glasgow ; and Captain J. Gray, A.M.I.E.E. (late R.A.F.). 
(MS. received March 6, 1922. Read IViarch 6, 1922.) 
Before the advent of the aeroplane and airship the gyroscope derived 
its practical importance from its applications to the torpedo and the 
gyroscopic compass, and neither of these applications originated in this 
country. With the introduction of aircraft the applications of the 
gyroscope become very numerous and of great importance. Navigation 
of such craft must be made precise by the provision of gyroscopic 
sextants ; photography from aeroplanes, to be accurate, must be carried 
out by means of special cameras stabilised so that the photographs are 
true vertical productions ; war aeroplanes must be steered and controlled 
in accordance with accurate dynamical principles, and in this respect 
the claims of the gyroscope cannot be ignored ; bombing from aeroplanes 
must be rendered accurate by designing the bombsight as part of an 
accurate stabiliser ; battleships must be provided with anti-aircraft devices 
controlled by stabilisers, and the guns on such ships must be controlled 
both with respect to the vertical and the horizontal, and in azimuth, by 
means of instruments of the greatest precision. 
The inventions described below form part of a series which have 
resulted, in great part, from long-continued research work carried out 
in the Natural Philosophy Institute of the University of Glasgow, and 
relate to apparatus for finding, maintaining, and thus defining, the true 
vertical and horizontal on aeroplanes and airships. The research was 
assisted, in its later stages, by means of a grant received from the Royal 
Society of Edinburgh (in 1915), and first models were made for the 
Admiralty and the Munitions Inventions Department of the Ministry of 
Munitions. The invention was adopted for bombing purposes by the 
R.N.A.S. in the autumn of 1917, but unfortunately, for reasons which 
cannot be discussed in this paper, the apparatus produced was not used 
over the German lines. 
A bombsight rigidly attached to an aeroplane is of little use, inasmuch 
as it shares in all the pitching and rolling motions of the machine. In 
order that a bomb dropped from an aeroplane should hit a target on 
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