presence of Mr. Davies Gilbert and some other gentlemen of a 
very remarkable kind, the result of which bears curiously on 
the investigations to which I have just alluded. A measured 
quantity of water was placed in a boiler, all the safety valves 
were most carefully closed, and every chance of the escape of 
steam prevented. The fire was now got up, and for some time 
the steam gauge indicated a regularly increasing pressure. At 
length, to the surprise of all, the pressure was seen slowly, but 
gradually, to diminish, and although the boiler plates became so 
hot as to char the wood which surrounded them, this remarkable 
phenomenon continued, and when the boiler had cooled it was 
found that no water had escaped. These investigators conceived 
no correct idea from this hazardous experiment, but it was the 
Cai gnard do la Tour experiment of enclosing elastic fluids in 
hermetically sealed tubes, repeated on a large scale, and it 
showed, as all the experiments of Boutigny show, that notwith- 
standing our boasted knowledge we are yet ignorant of the 
laws which govern the operations of heat when its excitation is 
elevated. The decomposition of water by heat, as discovered 
by Mr. Grove, belongs to this class of phenomena, and Dr. 
Robinson, of Armagh, in considering the experiment, speculates 
on the probability, that at a certain point heat may be changed 
into a chemical force, similar to those radiations from the sun 
which effect the changes now familiar to all of you in the 
photographic processes, to which the term Actinism has been 
generally applied. 
Although it will be my constant endeavour to explain with all 
care the useful applications of science; to show how thoroughly 
associated science and practice should be, l shall never fail to 
direct attention to those experimental evidences which enable 
us to interpretate the great phenomena of nature. As a culti- 
vator of physical science I feel that I should sacrifice half of 
the advantages to be derived from the study, if I failed to show 
the satisfactory manner in which advancing science opens out 
to the contemplative observer new harmonies in creation, and 
tends to exalt the mind to higher and holier aspirations. 
In connexion with heat, observation has proved to us nume- 
rous important points relative to its distribution over the earth’s 
