ADDRESS. Ixiii 
their rate of growth. It gives to the zoologist accurate representations of 
the most complex of his subjects, and of their organization, even to micro- 
scopic details. 
The engineer at home can ascertain by photographs transmitted by suc- 
cessive mails the weekly progress, brick by brick, board by board, nail by 
nail, of the most complex works on the Indian or other remote rail-roads. 
The physician can register every physiognomic phase accompanying the 
access, height, decrease, and passing away of imental disease. 
The humblest emigrant may carry with him miniatures, such as Dow could 
not have equalled in the perfection of their finish, of scenes and persons 
which will recall and revive the dearest affections of the home he has left. 
In its lowest application photography becomes an instrument of the 
criminal police. 
The first practical application of the electro-magnetic discovery was, as it 
should be, to the direct service of the philosophic inquirer: it was such an 
application of a delicate compass-needle as would show, by its deflection, 
the strength of the voltaic current. The possession of Schweigger’s ‘ gal- 
vanometer ’ enabled the -philosopher henceforth to detect and measure the 
_ minutest electro-dynamic actions. It led to the discovery by Seebeck 
of the conversion of heat into that kind of action; in short, of thermo- 
electricity. 
On Faraday’s demonstration—the converse of Oersted’s—that magnetism 
could produce electricity, and on the brilliant series of discoveries of that 
most exemplary investigator of natural laws, I need not dwell, in the pre- 
sence of so many who are better qualified than myself to comprehend and 
illustrate them. 
Remote as such profound conceptions and subtle trains of thought seem 
to be from the needs of every-day life, the most astounding of the practical 
augmentations of man’s power has sprung out of them. Nothing might 
seem less promising of profit than Oersted’s painfully-pursued experiments, 
with his little magnets, voltaic pile, and bits of copper-wire. Yet out of 
these has come the electric telegraph! Ocersted himself saw such an appli- 
cation of his convertibility of electricity into magnetism; and Schilling suc- 
cessfully applied the principle to the instantaneous communication of signs 
through distances of a few miles. The unrivalled resources of Wheat- 
stone’s inventive genius have made it practicable for all distances, as we 
have lately seen in the submergence and working of the electro-magnetic 
cord connecting the Old with the New World. 
Whoever has been engaged in the delicate physical and chemical expe- 
riments required in the present state of natural philosophy, will know how 
small is the expectation of success on the first trial of a new experiment in 
the laboratory. Only the experienced manipulator realizes how hard it is to 
foresee every condition requisite for success: but it is he who bears the 
bravest heart under failures, well assured that through them are acquired 
