Description:
- Object ID: ALSA 2013.01.02
- Made by: Unknown.
- Model: Unknown.
- Serial Number: Unknown.
- Date Made: Unknown.
- Approximate size: 12 X 1.5 X 1.7 cm.
- Accessories: n/a
- Condition: Good
Commentary:
A trough compass is used to mark magnetic north on the plotting paper on the plane table drawing board. This one has on one side a lever to lock the compass needle in place when it is not being used. .
A trough compass can be also called a plane table compass or declinator.
Lou Breton who donated this object also donated a plane table and tripod (ALSA 2012.02.01) and an alidade (ALSA 2012.02.02).
Source of Object: Donated by Lou Breton, ALS.
Notes: The Society has two other trough compasses, ALSA 2007.28.02 (Weir) and ALSA 2012.01.01 (Frederick).
References: Visit article The Survey Instrument Captain Cook Wanted to Learn – The Plane Table and Alidade for additional information.
Description by: Entered by Ed Titanich on December 23, 2024.