450 Transmission of Disturbances through Sea-water. [Mar. 21, 



March 21, 1889. 

 Professor G. Gr. STOKES, D.C.L., President, in the Chair. 



The Presents received were laid on the table, and thanks ordered 

 for them. 



The following Papers were read : 



I. " On the Velocity of Transmission through Sea-water of 

 Disturbances of large Amplitude caused by Explosions." 

 By RICHARD THRELFALL, M.A., Professor of Physics, and 

 JOHN FREDERICK ADAIR, M.A., Demonstrator of Physics, 

 University of Sydney. Communicated by Professor J. J. 

 THOMSON, F.R.S. Received March 14, 1889. 



(Abstract.) 



This paper contains an account of a large number of experiments 

 made with the object of determining the velocity of waves of com- 

 pression caused by explosions nnder water. 



The method adopted depended on the nse of a certain "gauge" 

 devised for the occasion, whereby the arrival of the disturbance at a 

 given point was transmitted to a chronograph. 



The disturbances themselves were caused by submarine explosions 

 of dynamite and guncotton in quantities varying from nine ounces to 

 four pounds. 



The distance over which the velocity was measured was about 

 200 yards. 



The water was that of the Pacific Ocean in the harbour of Port 

 Jackson, ET.S. Wales. 



The chronograph was of the falling pendulum description, and 

 fired the charge automatically. 



The absolute time was obtained by comparing the chronograph 

 tuning fork with an astronomical clock. 



The distance was obtained in terms of the standard yard of N.S. 

 Wales by means of trigonometrical survey. The chief results for 

 the range quoted are as follows : 



