278 



Mr. Mallet on the Physical Conditions 



Table XV. 



Comparison of Weight, Strength, ExteimbilUy, and Stiffness; Cast-iron being unity, within practical 



limits, to Static Forces only. 



The torsion from Colomb and Tredgold's results. 



Table XVI. 

 3Iolecular Properties of the principal Materials for Construction of Artillery. 



Col. 11, = hardness x 7;. 



Col. 12, from the Author's experiments, Trans. Brit. Ass. 



Table XVII. 

 Comparative Financial Selations of the imncipal Materials of Construction for Artillery. 



Note. — Cast-iron is taken as unity throughout. 



The relative strength is as opposed to static forces. 



The relative durability takes account only of abrasion and corrosion. 



Col. 10 = col. 6 X reciprocal of col. 8. 



