Derck's circular gauge dial
1920-1925
Circular Mears Fluid Flow ready reckoner calculator for liquids and gases
1955-1965
Westinghouse duct sizing calculator
1965
Ready reckoner for bolts and screws
Circular D20 Tank Capacity (Imperial) ready reckoner calculator in plastic sleeve by Fearn Calculators limited
1965-1975
Ready reckoner for screw threads
Ready reckoner for screw-cutting machines made 1970 for Gustav Wagner
1970
Lathe turning ready reckoner with plastic sleeve by IWA Rechenschieberfabrik F. Riehle KG
1960-1970
Flow Meter Orifice Calculator in card
1950-1960
Ready reckoner
1965-1975
Ready reckoner for drilling calculations
1965-1975
Plastic valve sizing calculating rule by Short & Mason Ltd.
1955-1970
Ready reckoner for Mansfeld with copyright by E. Willi
1965-1975
Ready reckoner for use with milling machine
1965-1975
Ready reckoner for screw threads
Circular Mears Steam Flow ready reckoner calculator in cardboard case with instructions
1955-1965
Circular ready reckoner weight for rolled steel section calculator with cardboard case by Fearns & Mear
1945-1955
"Marryat-Scott Lift Planning Rule"
1955
Circular A61 Re-order Point ready reckoner calculator in plastic pouch by Fearn Calculators limited
1965-1975
Circular ready reckoner calculator for pump pressure drop with various viscous fluids by Plenty & Son Limited
1960-1965