070 SUMMARY OF CURRENT RESEARCHES. 



elastically by bending and then suddenly let go, resumes its position of 

 equilibrium after a series of oscillations, more or less " damped." As 

 the " damping " (amortissement) depends on the internal structure, an 

 investigation of the rate at which the vibrations die away should give 

 useful information. It was found that the damping of a specimen of 

 soft iron was three times as rapid as that of a mild steel. A method of 

 measuring the damping is described. 



II. le Chatelier * considers that the method may be valuable, as 

 measuring a new elementary property of metals, which is possibly of 

 great importance in their practical applications. The desirability of 

 fully investigating this method of testing is insisted upon, and an out- 

 line programme of research is given. 



Friction in Compression Tests.f — G. H. Gulliver has studied the 

 effect of the friction of the crushing plates upon the yield-point of short 

 compression specimens. With plates harder than the material under 

 test, the end friction causes an increase in the apparent yield-point. 

 When the crushing plates are softer than the material under test, the 

 apparent strength of the specimen is diminished. Calculated numerical 

 values for both effects are given. 



Elastic Limits of Iron and Steel under Cyclical Variations of 

 Stress.^ — L- Bairstow finds that iron or steel is capable o*f adjusting 

 itself to variations of stress, cyclically applied, after a sufficient number of 

 repetitions. When the adjustment is complete the specimen is found to 

 have become perfectly elastic throughout the whole cycle, and fatigue 

 does not occur. An extension of length of specimen occurs during this 

 adjustment. The greater the extension, the greater is the amount by 

 which the elastic limits are raised. 



Gulliver, G. H. — Effect of Internal Friction in Cases of Compound Stress. 



Proc. Boy. Soc. Edin., xxix. (1909) pp. 427-31. 



Howard, J. E. — Endurance of Steels to Repeated Alternate Stresses. 



[In tests made on a machine in which the rotating test bar is submitted to 

 a bending stress, fracture resulted at stresses much below the elastic limit. 

 The existence of internal stresses is suggested as an explanation.] 



Proc. Int. Assoc, for Testing Materials, No. 5 (1909) 7 pp. (4 figs.). 



1 Rev. de Metallurgie, vi. (1909) pp. 887-9. 



t Proc. Roy. Soc. Edin., xxix. (1909) pp. 432-44 (6 figs.). 



X Proc. Roy. Soc, Series A, lxxxii. (1909) pp. 483-5. (Abstract.) 



