PROCEEDINGS OF SECTION J. 725 
certainty than contraction of area. I have left out the require- 
ment as to elastic limit which occurs in the American specifica- 
tions, because I fear it would be perplexing to the majority of 
those that have to use the specifications, and further, because I 
have never yet found an iron good in respect to tenacity and 
elongation that was not also up to the American standard as to 
elastic limit. 
In actually testing the material certain precautions are neces- 
sary. If possible, recourse should be had to a proper testing 
machine, such as exists at the Sydney or Melbourne University. 
Failing this, extemporised machines may be used, but in this case 
great care must be taken to ensure absence of friction, accuracy 
of leverage, and gradual application of load without shock or 
vibration. The preparation of the test-pieces also requires care, 
and my own experience of the difficulty of getting proper test- 
pieces made, especially in the case of flat bars or plate-iron, has 
induced me to have a special milling machine constructed, 
whereby the test-pieces can be properly prepared under my own 
supervision. Specimens of the work of this machine are upon 
the table. 
TABULAR STATEMENT OF SPECIFIED TESTS OF CAST AND 
Wrovucut I[rRon. 
1.—Cast IRon. 
Rankine a a ie |, Salts 1 -Lanesg. || 470 to 1036 
Trautwine 3 ft. 1 in. sq. 500 to 900 
Stoney 3 ft. 1 in. sq 847 
Victorian Water Supply 3 ft. 1 in. sq 672 
South Australian Railways 3 ft. | lin.sq 784 
American Bridge Companies | 4ft. 6in. | Tinisqes =| 500 
Author’s own tests Sith: iin sage 700 to 1050 
N.S.W. Railways— 
Penrith Bridge 3 ft. | 2in.x lin. 3024. 
| Victorian Water Supply 3 ft. | 2in.x.1in. 3360 
Prof. Warren’s highest 3 ft. | 2in. xin. 3136 
| Author’s own tests... 3 ft. | 2in.xlin. | 2116 to 2850 
