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peculiar drawing blows upon it, wbicb will soon raise it to a 
red heat, and enable him to light his fire. The nail becomes 
red-hot and emits its heat, and that light and heat are clearly 
obtained at the expense of dynamical energy with which the 
hammer had been used. There are some experiments which 
show in a striking manner the connection between light and 
electricity. I may speak of the phosphorescence of fluor 
spar, which if heated to a slight degree, becomes luminous for 
a short period. But after that light had been produced by 
heat and has departed, it will not immediately reappear 
under the influence of renewed heat, unless the fluor spar be 
subjected to the additional influence of an electrical discharge, 
and then the light may be again produced. That seems to 
indicate a remarkable connection between electricity and 
light. Again, in some machines recently invented, a powerful 
current of electricity is produced simply by turning the winch 
of the machine by hand. In that instance the dynamic 
energy of the hand is converted into electric energy and 
manifested as such. Thus it appears that all these various 
forms or manifestations of physical energy may be considered 
as modes of motion, and the hypothesis of their corporeal 
existence — of their being forms of matter — is entirely super- 
seded. As to the media by which these forms may be trans- 
mitted much may be said, but time will not permit me to go 
into that part of the subject. 
The common medium of communication between external 
objects and our organs of sense, may also be supposed to be 
vibratory motion. Sound as we all know is conveyed to the 
ear by the vibrations on the air, and the impressions of light 
are conveyed to the eye, and of heat to our organs of sen- 
sation, also by vibrations. The senses of sight, of touch, and 
of hearing are most evidently affected by vibrations ; but I 
think there is strong reason to believe that the senses of 
taste and smell, which are analogous, are affected in a similar 
manner. It is well known that the senses of both taste and 
smell are considerably blunted by the effect of cold — that if a 
piece of ice be taken in the mouth the taste is rendered com- 
paratively insensible, and that the odours of flowers are only 
perceived with difficulty in cold weather. It is notorious that 
odours of all kinds, whether pleasant or unpleasaat, are much 
more readily perceived in warm than in cold weather, and 
thus the vibratory motion of heat seems to be the medium of 
communication between the senses of smell and taste and 
external objects, much in the same way as the organs of seeing 
and hearing are affected by vibratory motion. 
It is, however, much to be regretted that manv of these 
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