Adjustable spirit level construction
Adjustable water level device
Adjusting arrangement for compass repeaters
Aid apparatus for level surveying instrument
Air bubble free compass and method of manufacturing same
Air-bubble level for portable tools
Aircraft attitude display instrument
Aircraft body-axis rotation measurement system
Aligned laser system having a combined level and square device
Alignment device
Alignment device utilizing components responsive to gravity
Alignment gage for dish antenna
Alignment tool and method for aligning large machinery
All angle borehole tool
All solid state analog gyromagnetic compass system
All-purpose level
Altered light navigation device
Analog inclination data system
Angle change detector
Angle change detector