XXviii PROCEEDINGS. 



SIXTH ORDINARY MEETING. 



Legislative Council Chamber, Halifax, 8th May, 1899. 



The PRESIDENT in the chair. 



A circular from the Eoyal Society of Canada, relative to the appoint- 

 ment of a delegate to the forthcoming meeting, was read and referred to 

 the Council for action. 



PROP. J. G. MACGREGOR communicated a " Note on the variation 

 with tension, of the elastic properties of vulcanised india-rubber," being 

 an account of some experiments made in his Laboratory at Dalhousie 

 College, by MR. W. A. MACDONALD. 



The experiments had been intended originally to deal with rigidity 

 only, but it had been -found possible to apply some of the observations 

 to the determination of Young's Modulus as well. 



The composition of the specimen of india-rubber used was not 

 known. It was in the form of a cylindrical cord and was fairly soft in 

 texture and grey in color, a freshly cut surface having a mottled 

 appearance. It had been obtained from Messrs. Thornton & Co., Edin- 

 burgh, and was both very true and very uniform in its circular cross 

 section. 



The method employed for determining the rigidity under tension 

 was the method of oscillation. It was necessary therefore to fix the 

 upper end firmly and to attach a weight-holder firmly to the lower end. 

 As the problem had been assigned to Mr. Macdonald as a class exercise 

 merely, and no appropriate gear for the attachment of the ends was 

 immediately available, he had to be contented with a makeshift method. 

 He drew the ends of the cord through pieces of glass tubing, previoxisly 

 coated internally with soft sealing wax, of considerably smaller diameter 

 than the cord, and then gently heated the tubes until the wax melted. 

 The tube at the upper end was fixed to a bracket, that at the lower end 

 carried a cork disc which served as a weight-holder. To reduce the 

 error due to lack of uniformity in the diameter of the cord near the 

 ends, produced by the pressure of the tubes, the cord selected for use 

 was a long one. Except in so far as the heating may have changed the 

 physical properties ot the cord near the lower end, the arrangement was 

 satisfactory enough for the comparatively small extensions for which it 

 was intended. But for the greater extensions, to which the earlier 

 results made it appear desirable to proceed, it was not suitable. For 



