Berry's strain gauge
Datecirca 1927
Inventory Number1999-1-0065
ClassificationGauge
Subject
Maker
F. F. Metzger
1890s - 1920s
Inventor
H. C. Berry
User
Harvard Engineering School
1918 - 1951
Cultural Region
Place of Origin
Place of Use
Dimensionscase: 5.5 × 57.2 × 20.3 cm (2 3/16 × 22 1/2 × 8 in.)
Material
Accessorieswooden box lined with velvet cushioning;
strain gauge;
iron bar;
steel rod contact points (2);
nails (3) wrapped in paper;
manual;
single stationery paper;
pamphlet (price list)
DescriptionThe instrument is in two pieces, both made of metal and about 55 cm long. One arm consists of two flat side strips made of Invar metal, which has a coefficient of expansion less than 1/28 of carbon steel and therefore makes it reliable for detecting small changes in shape. A space between them is maintained by two short braces fastened by screws.
Inserted in both ends of the arm are conical steel connecting points. The one on the right end of the arm is fixed, the one on the left pivots freely on a metal dowel and forms an arm of a bell-crank lever, that is, a lever with two arms at an angle to one another connected at the fulcrum. The contact point is housed in a square metal piece screwed between the two squares welded onto the ends of the strips. The other arm of the bell-crank lever is a flat piece of metal, the end of which depresses the gauge when pushed upward.
The contact point is held in place by a pair of metal strips. The other contact point is fixed on the right end of the bar with a bolt and two pieces that allow it to slide along the arm to adjust the length of the measurement.
The other arm, the "laying-off punch," is a long bar with a square cross-section. The bar has four holes, three evenly spaced in one half of the bar, the other at the other end of the bar, with a screw on the side of each hole to fasten contact points to make indentations of the proper width in the surface.
Kept in a brown wooden case with brass hinges, lined with purple, velvet cushioning. Three rectangular velvet cushions evenly spaced in the top part of the case. In the bottom part of the case, the velvet cushioning forming an outline of the instruments in the bottom part of the case.
Also in the case are several supporting documents, including a pamphlet by H.C. Berry describing different types of his strain gauges, several catalogs of B.C. Ames micrometer gauges, and a piece of stationery from Professor Albert Hartlein of the Harvard Graduate School of Engineering with the words "Professor Berry" written on it.
Also included are three drill bits, wrapped in brown paper, one with two needle points, one with two tapered points, and one with both points, one on either end.
Inserted in both ends of the arm are conical steel connecting points. The one on the right end of the arm is fixed, the one on the left pivots freely on a metal dowel and forms an arm of a bell-crank lever, that is, a lever with two arms at an angle to one another connected at the fulcrum. The contact point is housed in a square metal piece screwed between the two squares welded onto the ends of the strips. The other arm of the bell-crank lever is a flat piece of metal, the end of which depresses the gauge when pushed upward.
The contact point is held in place by a pair of metal strips. The other contact point is fixed on the right end of the bar with a bolt and two pieces that allow it to slide along the arm to adjust the length of the measurement.
The other arm, the "laying-off punch," is a long bar with a square cross-section. The bar has four holes, three evenly spaced in one half of the bar, the other at the other end of the bar, with a screw on the side of each hole to fasten contact points to make indentations of the proper width in the surface.
Kept in a brown wooden case with brass hinges, lined with purple, velvet cushioning. Three rectangular velvet cushions evenly spaced in the top part of the case. In the bottom part of the case, the velvet cushioning forming an outline of the instruments in the bottom part of the case.
Also in the case are several supporting documents, including a pamphlet by H.C. Berry describing different types of his strain gauges, several catalogs of B.C. Ames micrometer gauges, and a piece of stationery from Professor Albert Hartlein of the Harvard Graduate School of Engineering with the words "Professor Berry" written on it.
Also included are three drill bits, wrapped in brown paper, one with two needle points, one with two tapered points, and one with both points, one on either end.
Signedin middle of upper gauge arm: H.C. BERRY;
on left end of arm: MADE BY / F.F. METZGER / PHILA.;
on top half of dial: B.C. AMES CO. / WALTHAM MASS. / U.S.A.
Inscribedon bottom half of dial: 1/1000";
nails (3)marked: 55x1/8 / 90°C / the letter "C" inscribed in a diamond
manual: STRAIN GAGES/ H.C. BERRY / C.E. Dept., University of Pennsylvania / Philadelphia, Pa.
single stationery paper: HARVARD UNIVERSITY / GRADUATE SCHOOL OF ENGINEERING
on left side of stationery: ALBERT HAERTLEIN / Gordon McKay Professor of Civil Engineering
on right side of stationery: PIERCE HALL CAMBRIDGE 38, MASSACHUSETTS
written on paper: Professor Berry
pamphlet: PRICE LIST / FEB. 1, 1926 / AMES / MICROMETER / DIAL GAUGE HEADS. / Published by / B.C. AMES CO. / WALTHAM, MASS., U.S.A.
pamphlet: PRICE LIST / February 15, 1927 / AMES / Dial Gauge Heads / Upright Dial Gauges / Pocket Gauges / B.C. AMES CO. / WALTHAM, MASS.
written on top: Received 2/17/27
printed: Dial Gauge Heads and Attachments
FunctionMechanical strain gauge; measures the deformation of the surface of a structure when force is applied. The instrument magnifies the object's motion by means of a lever. One of the contact pointers is fixed on the bar, the other fixed to a bell-crank lever that pivots on a dowel at the same end of the arm. The other end of the lever pushes on a metal rod that connects to a dial.
Two metal points would be inserted into the holes on either side of the laying-off punch (square metal bar) and used to prick markings into the surface to be measured. This would set the gauge, that is, the length of the part of the surface being measured. The markings might be deepened using a drill. The strain gauge would then be placed on the surface, each contact point resting in the holes marked off by the laying-off punch. The button on top of the gauge would be pushed to zero the gauge. A load would be applied, and the strain produced by the load causes the pointer to turn, causing the lever to turn. Whatever minute motion the pointer makes when coming into contact with the surface is magnified and registered by the dial indicator.
Two metal points would be inserted into the holes on either side of the laying-off punch (square metal bar) and used to prick markings into the surface to be measured. This would set the gauge, that is, the length of the part of the surface being measured. The markings might be deepened using a drill. The strain gauge would then be placed on the surface, each contact point resting in the holes marked off by the laying-off punch. The button on top of the gauge would be pushed to zero the gauge. A load would be applied, and the strain produced by the load causes the pointer to turn, causing the lever to turn. Whatever minute motion the pointer makes when coming into contact with the surface is magnified and registered by the dial indicator.
Historical AttributesGauge was developed by H.C. Berry, a professor of civil engineering at the University of Pennsylvania. This is a variant on his earlier 8-inch and 2-inch gauges (see 1999-1-0083 and 1999-1-0084). The improvement is that the length of the gauge is adjustable. It was most likely used in Harvard's Graduate School of Engineering in the 1920s.
F. F. Metzger
Date: 1905-1930
Accessories: steel contact points (4);
strain gauges (2);
square bars (2);
dial gauge
Object number: 1999-1-0083
F. F. Metzger
Date: early 20th Century
Accessories: brown leatherbound wood case with purple stuffed velvet lining two metal locks in front;
steel rod contact points (4);
metal bar;
strain gauge;
card describing gauge ratio
Object number: 1999-1-0084
Gebrüder Haff
Date: 1960-1969
Accessories: plush-lined, hard green case
white card with instrument information in case
Object number: 1999-1-0005
Gottfried G. Ledder
Date: circa 1904
Accessories: triangular mahogany case
Object number: 1997-1-1857
Gebrüder Haff
Date: circa 1960
Accessories: black storage case
two white cards with conversion tables inside case
Object number: 1997-1-2000
George Erle Beggs
Date: early 20th-mid 20th Century
Accessories: 6 deformeter gauges;
22 plugs;
2 cylindrical plastic boxes containing screws and metal strips for fastening the ends of the structure;
metal stylus;
2 metal pins;
2 celluloid wedges;
1 rectangular celluloid piece with a wedge coming out of one end
Object number: 1999-1-0064
Breton Frères
Date: 1850-1890
Accessories: foot broken off
Object number: DW0392
C. L. Berger & Sons
Date: circa 1902
Accessories: pine case with lock (key not found); screwdriver; leather strap; sunshade; dust cover; tripod (see 5161b)
Object number: 5161a
G. Coradi
Date: circa 1911
Accessories: conversion table on white card in instrument case; instrument case
Object number: 1999-1-0068
Gebrüder Haff
Date: circa 1957
Accessories: white card with instrument information inside case
Object number: 1997-1-0447
Forster
Date: 1950-1960
Accessories: spare ink cartridges; pen attachments
am auxiliary box containing small Allen wrench, scotch tape, extra parts, and storage instructions
Object number: 1999-1-0054
See also/See also
