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Three qualities of brick were used. First, a good quality of No. 1 

 paving brick ; second, a medium quality of No. 2 paving brick ; third, a 

 soft quality of ordinary building brick. The brick were approximately 

 2"x4"x8" in dimension and were cemented together in order to obtain the 

 specimen of desired length. 



Following is the mean value obtained for each of the above qualities of 

 brick : 



No. 1 brick (hard) Coefficient of Expansion per degree F = .00000401. 



No. 2 brick (medium). Coefficient of Expansion per degree F = 

 .00000401. 



No. 3 brick (soft). Coefficient of Expansion per degree F = .00000393. 



It will be noted that the hardness of the brick has little to do with the 

 amount of expansion, the three qualities giving essentially the same values. 



