Benton — Properties of Catgut Musical Strings. 391 



lbs. per sq. in. If observations taken immediately after apply- 

 ing the loads had been used, instead of those after the disap- 

 pearance of the after-effect, we would have about 400 kg. per 

 mm 2 for Young's modulus ; and this latter figure represents 

 the elastic resistance of the material to a stress applied for a 

 short time, as in longitudinal vibrations of the string. 



Limit of Elasticity. — As is seen from the table, slight per- 

 manent set appears, though not with great certainty, after 

 applying 2*5 kg (+0*5 kg. for the hanger). That makes the 

 limit of elasticity about 8 kg. per mm 2 , corresponding to a 

 strain of 2 - T per cent. 



Stress-strain .Relation. — The results tabulated above are 

 shown graphically in figure 7. It is clear from it that Hooke's 

 law is approximately true ; but the results obtained are too 

 irregular to furnish ground for any definite statement as to 

 deviations from Hooke's law. t 



Sewickley, Penu. 



