Vernier-Type Caliper

IHPST

Accession Number: 2017.ihpst.46

Instrument Name: Vernier-Type Caliper

Description:

A rectangular, foam-lined wooden box contains an metal precision measuring instrument. The instument has a round, glass-faced dial at one end whose scale is divided into one hundred increments. To the left of this is a variable opening – a measuring jaw – that ends in sharpened points. These points are secured in place with small set screws. The left (movable) jaw slides along the instrument body in order to adjust the measuring jaw to the size of the object being measured. The slide on which the left jaw travels has numbers engraved on its surface.

The case also contains a metal 10mm reference that is used to calibrate the instrument. This is contained in a small cylindrical plastic container with a red lid.

The case also contains a cardboard tag.

Alternative Name: Pin-Point Calipers

Primary Materials: Iron alloy, Wood

Markings:

The box has two labels on the upper right corner of the lid. The topmost reads as follows:

FRANK COX SALES LIMITED
INSTRUMENTS & GAUGES
CALIBRATION SERVICE
BRAMPTON – ONTARIO – CANADA
(416) 457-9190

Below this is a label that reads:

CANADIAN CENTRAL GAUGE LABORATORY
GAUGE AND INSTRUMENT
SERVICE AND CALIBRATION
AGENT: FRANK COX SALES LTD.

On the right side of the lid is a white sticker on which is written:

V77718
#40

A cardboard tag in the box has the following written on it:

REPLACEMENT
LOCK SCREWS
PART# P.T.48

Dimensions (cm):

(Box) Length: 32.5, Width: 20.2 cm, Height: 7cm.

Function:

A caliper is used to precisely measure the distance between two points.

This particular instrument was used to measure the x-ray images of the 2nd metacarpal bone in studies that sought to determine the relationship between bone dimension and density.

Condition:

Very Good: There are some minor abrasions and dents in the wooden case.

Manufacturer: John Bull British Indicators Ltd.

Date of Manufacture: c. 1970

Provenance:

This instrument was donated by Dr. Cyril Gryfe in the Fall of 2016.

Dr. Gryfe used this instrument in investigations that sought to correlate the dimensions of a metacarpal bone, measured on an x-ray image, with a bone density reference determined through post-mortem chemical analysis of representative human bones. Dr. Gryfe, a geriatrician, was among a number of researchers seeking a method of tracking bone-density loss, before the development of ultrasonography and CT scanning of bone. The goal was to establish a routine screen for osteoporosis.

Dr. Gryfe contributed to published collaborative studies in this area while he was based in London, UK. However, this instrument was not used in those studies but was purchased when he returned to Toronto. The results of his research at Baycrest Centre for Geriatric Care was shared informally with a group of researchers interested in bone diseases at the University of Toronto, organized and led by Dr. Joan Harrison (d. 2016).

Additional Information and References:

C. I. Gryfe, A. N. Exton-Smith and R. J. C. Stewart. “Determination of the Amount of Bone in the Metacarpal.” Age and Ageing 1 (1972), 213-221.

C. I Gryfe. “Bone Loss in Primary Hyperparathyroidism.” CMA Journal 109 (1973), 479-482.

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