Apeil 15, 1898.] 



SCIENCE. 



523 



but one-eighth the initial section of the un- 

 strained rubber. 



Permanent set occurs to an exceedingly 

 slight extent, and its value is dependent 

 upon the maximum load and independent 

 of the elastic properties of the substance. 

 The set of the material would not be noticed 

 in ordinary use. Permanent loads produce 

 permanent, continuous, extension and, in 

 time, fracture. This was found to be true 

 for loads rising from 40 to 330 pounds per 

 square inch (2.8 to 23.18 kgs. per sq. cm.), 

 and stress-strain diagrams for two weeks 

 under small loads showed steady elongation. 



Plotting curves having for their coordi- 

 nates loads per unit of area and areas of 

 section of test-piece at point of maximum 

 reduction, the stress-strain diagram thus 

 produced becomes altered in form and 

 similar to those of other materials plotted 

 in the usual manner. It has the same cur- 

 vature at the initial stage, the same straight 

 line to an (apparent) elastic limit, and 

 finally a steady, but slight, rise with in- 

 creasing loads, with a sudden break at the 

 end. The highest load measured in these 

 experiments was 810 pounds per square 

 inch (56.7 kgs. per sq. cm.). The quality 

 employed, in all cases, was that of the 

 stationers' elastic bands. 



In this connection a recent article by 

 Professor R. A. Fessenden has peculiar in- 

 terest. He had noticed that, on making a 

 fresh cut in a piece of rubber and then 

 stretching it, using a microscope to reveal 

 any peculiarities of appearance, the surface 

 showed a curious sponge-like structure, 

 with odd little excrescences gradually pro- 

 truded, as the strain was increased, ex- 

 uding from the pores of the substance. 

 He thus indicates the existence in the ma- 

 terial of two components : a hard and 

 horn-like substance, and a jelly-like matter 

 in its pores. He finds the same in other 

 highly elastic substances. He offers a curi- 

 ous, but none-the-less notable, theory to ac- 



count for the properties of this singular 

 material.* The practically perfect elas- 

 ticity exhibited in the experiments here de- 

 scribed, as made in the Sibley College lab- 

 oratories, lends confirmation to many of the 

 ideas presented by that investigator, who 

 indicated the form of the elastic curve for 

 this curious substance in advance of its 

 determination by experiment, and who 

 based upon his theory of its construction 

 explanations of its thermodynamic proper- 

 ties and actually produced, artificially, sub- 

 stances having similar elasticf properties. 

 R. H. Thurston. 

 Sibley College, Coenell Ukiveesiiy, 

 March 15, 1898. 



BRADNEY BEVERLEY GRIFFIN. 



Through the untimely death of Bradney 

 B. Griffin, who died on March 26th at the 

 age of twenty-six years, zoology has lost an 

 able student and a promising investigator. 

 He was the son of Dr. Bradney G-rifSn, of 

 New York, and received his earlier educa- 

 tion at the College of the City of New 

 York, where he graduated in 1894. Mr. 

 Griffin then became a graduate student in 

 zoology at Columbia University, where he 

 subsequently won a fellowship and took 

 part in the zoological expeditions to the 

 northwest coast, sent out by that institution 

 in the summers of 1896 and 1897. He was 

 the author, wholly or in part, of several 

 papers relating to the fauna of that region, 

 one of which, dealing with the nemerteans 

 of Puget Sound and describing a number of 

 species new to science, had been sent to 



* Journal of the Franklin Institute, September, 

 1896. See also Watts Dictionary, First Edition, 

 Vol. 11., p. 738— Caoutchouc. 



t Thus : Sodium stearate, dissolved in 5 to 20 parts 

 hot water and permitted to set as a jelly, gives, -when 

 cold, stress-strain diagrams like those of caoutchouc. 

 When squeezed dry by hand, however, this compound 

 becomes at once brittle and powdery. As a jelly it 

 behaves like animal muscle in many ways and is 

 polarized to electric waves. 



