General Information

Serial #

N/A

Part Number

12

Total Parts

16

AKA

glass scale

Patents

N/A

General Description

clear glass

Dimensions

Note: These reflect the general size for storage and are not necessarily representative of the object's true dimensions.

Length

22.5 cm

Width

2.1 cm

Height

N/A

Thickness

N/A

Weight

N/A

Diameter

N/A

Volume

N/A

Lexicon

Group

Metrology

Category

Length

Sub-Category

N/A

Manufacturer

AKA

Wild

Country

Switzerland

State/Province

Unknown

City

Unknown

Context

Country

Canada

State/Province

Ontario

Period

presumably c. late 1960s- early 1990s.

Canada

Accessory for plotter used in Canada's national mapping program c. 1960s-early 1990s, and is an example of the last analogue plotting devices used by the Topographic Service of Canada. With the exception of the Wild A10 [few of which were used in Canada], this machine was the most sophisticated plotter available before digital technology. This machine was converted c. 1995-96 to digitize the motions (X,Y & Z) with the addition of encoders and a control pad which interfaced to a computer. The Kern encoders and control module were installed by Terra Surveys of Ottawa when they rented this machine for the MOM project, completing the large scale mapping of Riyadh, Saudi Arabia. The A8 was on loan to Terra for the duration of the project's digital compilation stage. [Ref. 1]

Function

To establish the plotting scale to be used when mapping.

Technical

One of 15 glass scales from Group IV (imperial graduation) set available as an accessory for use with A8 plotter. Scales are inserted in a holder directly attached to the z column and projected under strong magnification onto a ground glass screen in front of the operator. [Ref.3, p.17] The rule [glass scale] must correspond to the model scale [instrument scale] in order to enable the operator to read the elevations. Wild provided a set of 4 tables, one for each of the 4 different groups of rules [glass scales] available, to facilitate the selection of the appropriate rule and [ratio] gear for a given plotting scale. [Ref. 2, p.32] Group IV set consists of scales 1:3200; 1:3600; 1:4000; 1:4800; 1:6000; 1:7200; 1:8000; 1:9600; 1:12 000; 1:14 400; 1:16 000; 1:18 000; 1:21 600; 1:24 000; 1:27 000 feet. Selected scales serve for direct elevation reading at specific map scales: this rule 1:18 000 may be read directly as 1 inch= 1500 feet. [Ref. 3, p. 26] Rules are unnecessary when using [Kern] digital elevation counter.

Area Notes

Unknown

Details

Markings

"1: 18 000/ feet" and scale etched into glass. "18 000 " printed by hand on both long side edges of rule; "V" printed by hand on one short side edge.

Missing

None.

Finish

Clear glass rule bears black markings.

Decoration

N/A