Stress and Strain on the Properties of Matter. 



89 



process of wire drawing. Accordingly by request, Messrs. Johnson 

 and Matthey with their usual courtesy prepared specimens of platinum, 

 silver, copper, aluminium, lead, platinum-silver and German silver in 

 the same manner and of the same degree of purity as before. The 

 wire -drawers had received special instructions to avoid kinks and to 

 secure uniformity in the diameters of the wires throughout their 

 lengths. Experiment T, which may be taken as representative of the 

 degree of uniformity obtained in the diameter of the various wires, 

 shows that in this last respect the instructions had been well carried 

 out ; nor could any kinks be detected in the wires. The results given 

 in Experiment I were obtained by means of a gauge reading to y^c* n 

 of a millimetre ; by estimation it was easy to measure to yoV o^ n °f 

 a millimetre. 



Experiment I. 



Distance in feet from one 

 end of the wire at which 

 the gauge was applied. 



Gauge-reading in 

 centimetres. 



1-5 



0-1088 



3 



0-1098 



4-5 



0-1087 



6-0 



0-1091 



7 5 



0-1092 



9-0 



0-1089 



10-5 



0-1091 



12 



0-1088 



13-5 



0'1093 



15 



0-1096 



16-5 



-1089 



18 -0 



0-1091 



19-5 



1091 



21 -0 



0-1091 



22-5 



0-1092 



24-0 



0-1092 



25-5 



0-1088 



27 



0-1092 



28-5 



0-1093 



30 



1093 



The mean value of the gauge-readings is 0*10918, and in no case 

 does a gauge-reading differ from this mean by more than £ per cent. 

 After the diameter had been determined for each of the wires in a 

 similar manner by means of the gauge, they were made into coils of 

 more than one foot diameter, and the diameter again determined from 

 the. apparent loss of mass in water at 4° C. and from the length. 

 The values for the diameters obtained by the last method agreed very 

 closely with those got by means of the gauge. 



H 2 



