Correspondence and papers re. Disc Signalling, including 'Handbook on Signalling by Means of Discs, Invented by Lieut.-Colonel B. R. Dietz' (1908) and 'Memorandum for Signalers who are detailed to carry the Signalling Disc'.
Correspondence and papers re. Disc Signalling, including 'Handbook on Signalling by Means of Discs, Invented by Lieut.-Colonel B. R. Dietz' (1908) and 'Memorandum for Signallers who are detailed to carry the Signalling Disc'. [Pack No. 27]