346 ANNUAL REPORT 
scrves much more extended use than it has been receiving so far in 
American practice. 
Crushing tests are superior to tensile strength tests in more than one 
respect. They not only indicate the true strength of the cement, but also 
are not so liable to experimental errors. 
Nea a RD C7 
Le 7S 
AS H 
MAE 
i 
te oe 
NAR mean THT 
i) : ae 
\.' 
are a 
Fig. 66. Amsler-Laffen machine for crushing test. 
Larger hydraulic machines for testing concrete cubes are now also on 
the market at prices within the reach of many testing laboratories. Testing 
inachines depending on screw pressures and spring manometers are as a 
rule less reliable than the hydraulic machines. 
ROT) 
