Balloon theodolite by E.R. Watts & Son
1917
Balloon theodolite by Cary
1938
Balloon theodolite Mark D by Cary
1935
Balloon theodolite by Cary
Pilot balloon theodolite by Otto Fennel Sohne of Kassel
1939
Balloon theodolite by E.R. Watts & Son
1940
Balloon theodolite by Cary
1935
Pilot balloon theodolite by Cary & Co.
Pilot balloon theodolite
Balloon theodolite
1955-1960