538 REPORT—1896. 
Calibration of Instruments used in Engineering Laboratories.—Report 
of the Committee, consisting of Professor A. B. W. KENNEDY, F.R.S. 
(Chairman), Professor J. A. Ewing, F’.R.S., Professor D. S. 
CapPER, Professor T. H. BEARE, and Professor W. C. Unwin, 
ERS. (Secretary). (Drawn up by the Secretary.) 
Tr was stated in the previous report, presented at Ipswich in 1895, that 
the Committee had decided initially to investigate the accuracy of instru- 
ments for measuring the tension coefficient of elasticity, or Young’s 
modulus. 
It was decided that sets of standard test bars should be prepared to 
be subjected to tension and the extensions measured by the instruments 
in use in different engineering laboratories. The forms of the test bars 
are shown in figs. 1 and 2. Two of the standard test bars of each set 
were cylindrical bars with screwed ends suitable for use with shackles 
having spherical seatings. The third bar of each set was a flat bar 
suitable for wedge grips. All the cylindrical bars were cut from a single 
bar of specially strong steel rolled for the Committee by the Blenavon 
Company. The flat bars were cut from a single plate of good mild steel. 
Four sets were prepared, of which two were used for most of the measure- 
ments. The bars were marked as follows : 
Flat bars, A, B, C, D, of mild steel, approximately 2 inches by } inch 
in section. 
Cylindrical bars, E, F, G, H, of special steel, approximately 1} inch in 
diameter. 
Cylindrical bars, K, L, M, N, of special steel, approximately ? inch in 
diameter. 
The bars were carefully prepared by Mr. R. W. Munro. The 
cylindrical bars had marked gauge points suitable for extensometers 
8 inches, 10 inches, 16 inches, or 20 inches in length. The flat bars had 
gauge points for extensometers 8 inches or 10 inches in length. 
In order to obtain some preliminary information as to the mechanical 
properties of the standard bars, one round bar and one flat bar were 
tested in the testing machine at the Central Technical College. The 
following table gives the results obtained : 
Preliminary Tests of Materials used for Standard Bars. 
TENSION EXPERIMENTS. 
7 
Yield Point Maximum Breaking | 
Load Load 
Mark] _: : : - Elonga- Con- E. 
ow Dimensions. Area. tion on traction} Tons 
Ban Inches Sq. in. Load | Tons Tons | Tons 8in. |of Area per 
Tons | per Tons per Tons per percent,|percent.| sq. in. 
sq. in. sq. in. sq. in. 
D 2:000 x 0°507 | 1°014 | 16:19 | 15:97 | 23°725) 23°40 ee 19°48 32 62 Sees 
N 0°750 diam. | 0°4418 | 9:00 | 20:37 [15-725] 35°59 | 13:76] 31-14 |° 24°5 42 
ee ee ee ee ee eee eee ea ee 
Bar D was exac:ly similar to the flat bars A, B, C. 
Bar N was of th2 same steel as standard bars marked E, I’, K, L, &c. 
a a 
