xvi rROCEEUINGS. yi'cbniary c^th, igog. 



experiments on the ignition point of gases by the method of 

 adiabatic compression suggested by Professor Nernst. 



In the first experiments tried the compression was effected 

 in a strong glass tube, and photographs of the explosion were 

 taken ow a rapidly moving trim. The photographs showed that 

 the ignition was not set up instantaneously throughout the 

 whole mass of compressed gas, but began at one point, which 

 might be varied according to the velocity of the piston. In a 

 mixture of hydrogen and oxygen 'detonation' is very rapidly 

 set up, but not instantaneously. 



The later experiments were made in a steel lube, a window 

 being inserted near the lower end of the tube so as to observe 

 the flame i)roduced. 



Ordinary Meeting, February 23rd, 1909. 



Professor H. B. Dixon, M.A., F.R.S., President, 

 in the Chair. 



The thanks of the members were voted to the donors of the 

 books U])on the tables. 



The President made reference to the recent purchase by 

 the Society, of a chronometer watch belonging to the late 

 Dr. J. P. Joule, which the Council had resolved to place in 

 one of the Society's rooms, as a memorial of a distinguished 

 past President, whose work on the mechanical ccpiivalent of 

 heat, created a landmark in the history of science. 



Mr. T. Thorp, F.R.A.S., described a simple method of 

 silvering lr;msparent grating replicas, whether i)lane or mounted 

 on curved surfaces. The process is a modification of the (juick- 

 silver and tinfoil method used for ordinary minors before the 

 wet silvering process had been discovered. 



