General Information

Serial #

N/A

Part Number

3

Total Parts

4

AKA

N/A

Patents

N/A

General Description

METAL (?) MIRROR/ CELLOPHANE PAPER DISK

Dimensions

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

Length

N/A

Width

N/A

Height

N/A

Thickness

N/A

Weight

N/A

Diameter

2.0 cm

Volume

N/A

Lexicon

Group

Energy-electric

Category

Measurement

Sub-Category

N/A

Manufacturer

AKA

Cambridge

Country

England

State/Province

Unknown

City

Cambridge

Context

Country

Canada

State/Province

Ontario

Period

THESE MIRRORS NEVER USED; THIS TYPE/STYLE PROBABLY USED 1920S+

Canada

PART OF A COLLECTION OF PHYSICS LABORATORY AND CLASSROOM DEMONSTRATION APPARATUS FROM MCMASTER UNIVERSITY. FOUNDED IN 1887 MCMASTER WAS ORIGINALLY A BAPTIST INSTITUTION, AND WAS LOCATED IN TORONTO. IN 1930 THE UNIVERSITY AND ITS STUDENT POPULATION OF 500 WAS MOVED TO HAMILTON, ONT. (REF. 1)

Function

USED AS REPLACEMENTS FOR BROKEN OR DAMAGED MIRRORS ON VIBRATION GALVANOMETERS.

Technical

THE MOST SENSITIVE GALVANOMETERS AND SOME ELECTROMETERS USE A PIECE OF FERROUS METAL AFFIXED TO A SMALL MIRROR SUSPENDED ON A FINE WIRE. THIS WIRE WAS VERY VULNERABLE TO VIBRATION OR SHOCK, OR TO DAMAGE CAUSED BY TOO HIGH A CURRENT BEING APPLIED TO IT. THUS, THE SUSPENSION WIRE AND MAGNET/MIRROR HAD TO BE REPLACED ON A REGULAR BASIS. IT WAS A TEDIOUS AND PAINSTAKING PROCEDURE. (REF. 1)

Area Notes

Unknown

Details

Markings

Some text faintly visible on paper disks; one reads in part "..E DRY/...NG CO. LTD."

Missing

NONE.

Finish

MIRROR SEALED WITHIN OPAQUE GOLD-COLOURED CELLOPHANE DISK

Decoration

N/A