KEPOBTS 



ON THE 



STATE OF SCIENCE 



Report of the Committee, consisting of Professor Sir William 

 Thomson, Professor Clerk Maxwell, Professor Tait, Dr. C. W. 

 Siemens, Mr. F. J. Bramwell, and Mr. J. T. Bottomley, for com- 

 mencing Secular Experiments upon the Elasticity of Wires. 

 Drawn up by J. T. Bottomley. 



At the last meeting of the British Association, the arrangements for sus- 

 pending wires for secular experiments in the tube which has been erected 

 in the tower of the Glasgow University Buildings, and for observing these 

 wires, were described and reported as complete. Some improvements 

 have since been found necessary ; but, so far as these are concerned, there 

 is not much to add to the report then given. 



The long iron tube has been closed at the top and bottom so as to keep 

 out currents of air and dust, and the joints of the tube have been carefully 

 caulked. J 



Some improvements in the cathetometer used for observing the marks 

 on the wires were also found to be required, but the instrument is now 

 satisfactory. 



Six wires have now been suspended in the tube; their stretching 

 weights have been attached to them, and they have been carefully marked 

 and measured. These wires are suspended in pairs— two of gold, two of 

 platinum, and two of palladium. One of each of the pairs is loaded with 

 a weight equal to one-twentieth of its breaking weight, and the other of 

 each pair with a weight equal to one-half of its breaking weight. The 

 points of suspension for each pair are very close together, so that any 

 yielding of the place of support affects both wires equally. 



Each wire is marked with paint marks, and there are other marks on 

 the wires and on the weights attached to them where positions have been 

 determined. These marks are described in a laboratory book which is at 

 present kept in the room of the Professor of Natural Philosophy in the 

 University of Glasgow. The measurements that have been made, and 

 the experiments that have been undertaken in connection with the work 

 assigned to the Committee, are all being entered in this book. This, 



