Description:
- Object ID: ALSA 2010.06.04
- Made by: The J. Frank Raw Co. Ltd., Toronto
- Model: T.S. 1964 (see commentary)
- Serial Number: Unknown.
- Date Made: Circa 1964.
- Approximate size: 45.5 cm x 3.5 cm.. Sights are 11.5 cm high.
- Accessories: Leather case.
- Condition: Good
Commentary:
An open-sight alidade can only be used to determine the direction of an objects in plane table mapping. It is limited in that the object has to be close to the level of the plane table. It is limited in its application as it does not have cross hairs so it can not be used to determine distances using stadia. Also because it does not have vertical circles it cannot be used to determine difference in height.
This open-sight alidade is marked “T.S. 1964. Made by the Frank Raw Company Ltd Toronto.” T.S. 1964 could be the model number and 1964 the date it was made. The straight edge part is marked with graduations in inches (6 inches, plus an additional inch graduated in tenths of an inch).
The rigid leather case is 48 cm X 6 cm X 4 cm. The end of the case is stamped `TS1964`. On the back of the case are two belt loops.
The accession for this objects also included a plane table (ALSA 2010.06.03), a plane table tripod (ALSA 2010.06.02) and an alidade (ALSA 2010.06.07).
Source of Object: Donated by Steve Cherwonick, ALS#238.
Notes: The Society has only one in its collection.
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. Gordon Olsson on February 1, 2026.