502 
The British Association. 
[October, 
isation of light in its passage through electrified dielectrics, 
and on its reflection at the surface of a magnet. To take 
one more instance, there are the infinitesimal ripples of the 
vibrating plate in Mr. Graham Bell’s most marvellous in- 
vention. Of the nodes and ventral segments in the plate 
of the telephone which actually converts sound into electri- 
city and electricity into sound, we can at present form no 
conception. All that can now be said is that the most per- 
fect specimens of Chladni’s sand figures on a vibrating 
plate, or of Kundt’s lycopodium heaps in a musical tube, or 
even Mr. Sedley Taylor’s more delicate vortices in the films 
of the phoneidoscope, are rough and sketchy compared with 
these. For notwithstanding the faCt that in the movements 
of the telephone-plate we have actually in our hand the 
solution of that Old World problem, the construction of a 
speaking-machine, yet the characters in which that solution 
is expressed are too small for our powers of decipherment. 
In movements such as these we seem to lose sight of the 
distinction, or perhaps we have unconsciously passed the 
boundary between massive and molecular motion. Through 
the phonograph we have not only a transformation, but a 
permanent and tangible record of the mechanism of speech. 
But the differences upon which articulation (apart from 
loudness, pitch, and quality) depends appear from the expe- 
riments of Fleeming Jenkin, and of others, to be of micro- 
scopic size. The microphone affords another instance of 
the unexpected value of minute variations — in this case of 
eleCtric currents ; and it is remarkable that the gist of the 
instrument seems to lie in obtaining and perfecting that 
which electricians have hitherto most scrupulously avoided, 
viz., loose contaCt. Once more, Mr. De la Rue has brought 
forward, as one of the results derived from his stupendous 
battery of 10,000 cells, strong evidence for supposing that 
a voltaic discharge, even when apparently continuous, may 
still be an intermittent phenomenon ; but all that is known 
of the period of such intermittence is, that it must recur at 
exceedingly short intervals. And in connection with this 
subject it may be added that, whatever may be the ultimate 
explanation of the strange stratification which the voltaic 
discharge undergoes in rarefied gases, it is clear that the 
alternate disposition of light and darkness must be dependent 
on some periodic distribution in space or sequence in time 
which can at present be dealt with only in a very general 
way. In the exhausted column we have a vehicle for elec- 
tricity not constant like an ordinary conductor, but itself 
modified by the passage of the discharge, and perhaps sub- 
