Benton — Properties of Catgut Musical Strings. 385 



(0*0035 g. per cm. of length) by the well-known formula for 

 transverse vibrations of strings, and comes out about 6 kg., or 

 about one-half of the breaking load. During the above experi- 

 ments the string carried a load of 1*0 kg, and the temperature 

 was 20 to 25° C. The order of magnitude of the changes was 

 0*0002 of the length of the string for each cm. of mercury of 

 vapor tension. Precise determination of the dependence of 

 length on humidity was made prohibitively difficult by the 

 phenomena described in the following paragraph. 



After-effects. — Whenever any change was produced in the 

 conditions, the catgut did not at once come into equilibrium 

 under the new conditions, but did so only gradually. Thus, 



Figure 1. — Length and Humidity as Functions of Time. 



when the load upon it was changed, it exhibited in marked 

 degree the well-known elastic after-effect, requiring some days 

 to come to sensible equilibrium, during which time the change 

 in length due to change in load increased by about 25 per cent 

 of its final amount. It was found also that the stretch due to 

 humidity tended to continue after a change of humidity ceased ; 

 this could easily be seen in the fluctuations of humidity accom- 

 panying changes of weather ; but no facilities for controlling 

 humidity were available, and so no attempt could be made to 

 study these phenomena thoroughly. No doubt some time is 

 required for moisture to penetrate into the interior of the cat- 

 gut. The curves of figure 1 represent change of length of the 



