38-1 Benton — Properties of Catgut Musical Strings. 



Catgut string, -038 cm in diameter. 

 Average breaking load before special treatment, 4*5 kg. 



Number 

 of 



Treatment. 



Breaking 

 load 



tests. 





in kgs. 



2 



Soaked $■ hr. in water at 30° C, then tested 







while wet 



2-1 



1 



" dried, then 







tested 



5-0 



2 



Soaked '1 hr. in water at 30° C, dried for 







five davs, then tested 



4-3, 4-4 



1 



Soaked 5 min. in water at 90° C, then tested 



less 





while wet 



than 0-5 



4 



" " " dried, then 







tested 



1-0-1-9 



Elongation at Rupture. — A piece 0*062 cm in diameter, and 

 5.9cm ] ori g 5 stretched to 7 # cm just before rupture, or 19 per 

 cent of its original length. Another test gave 15 per cent. 

 These figures include whatever stretching was due to untwist- 

 ing. After rupture the pieces were too much frayed out for 

 any determination of their length. 



Specific gravity. — By weighing a piece of catgut (not treated 

 with water) of known length and cross section, its specific 

 gravity was determined as 1*18 (±0-01). 



All the remaining experiments to be described were made 

 on a violin E-string, 150 cm long and 0'062 cm in mean diameter 

 (the diameter was not quite uniform, varying between 0*059 

 and 0*65). It was freed from its original torsion on August 

 20, 1904:, by soaking one and a half hours in water of 30° C, 

 and while drying it supported a load of 0'5 kg. The experi- 

 ments were carried on from time to time during the following 

 year, at intervals during the prosecution of other work. 



Hygroscopic properties. — Upon setting up this string and 

 sighting with a micrometer telescope at a point near its lower 

 end, it was at once seen that the length of the string did not 

 remain constant ; and by observing at intervals and determin- 

 ing the humidity of the air at the same time, it was easily 

 demonstrated that the string stretched when the dampness 

 increased and contracted when it decreased. This is in accord- 

 ance with the well-known tendency of violin strings to break 

 in dry weather. When the weather is damp the string has to 

 be tightened to maintain the tension to keep it in tune ; with 

 increasing dryness its tension increases until finally it snaps. 

 The actual tension required on a violin E-string to produce the 

 proper pitch of 640 vibrations per second may be computed 

 from the length of string (about 33 cm ) and its specific mass 



