SCIENTIFIC SUMMARY. 
109 
the blending of colour with the moving body, to heighten the emotional in- 
fluence. In the discussion which followed, the opinion was expressed that 
though the writers had done good service in pointing out the educability of 
the various senses, and the parallelism which runs through their aesthetical 
use, they had not even attempted to prove that the pleasure experienced on 
looking at graceful and regular figures amoimted in any sense to emotion. 
To fulfil that indication it should move to tears, incite to heroic deeds, or 
stimulate to pity and charity. This music, which had the undoubted power 
of suggesting noble ideas, was well known to do, as had been grandly 
described in the “ Alexander’s Feast” of the poet Dryden. In giving an 
extended and somewhat metaphorical sense to the word music, they were 
only recurring to the original meaning of the Greek word, which included all 
forms of artistic enjoyment. At most, the contemplation of graceful curves 
and harmonious colour could gratify the sense of proportion, and might in 
the mind of a mathematician produce some sentiment akin to beauty ; all 
beyond must be due mainly to association. If their argument were carried 
to its bitter end it might be suggested that the praying machine of the 
Buddhists would im in time and by cultivation ” beget a sense of religion in 
the worshipper who turned its handle. 
Magnetic notation of the Plane of Polarisation of Light under the Influ- 
ence of the Earth . — This has been studied by M. Henri Becquerel, and the 
result communicated to the Academie des Sciences. Between a Jellett 
polariser and a telescopic analyzer mounted on a divided circle is placed a 
tube half a metre in length, terminated by parallel plates, and containing 
carbon bisulphide. Mirrors at the ends of the tube give successive reflec- 
tions, and augment the observed rotation. In this experiment the ray 
traversed the tube five times, thus corresponding to a length of 2*5 metres 
of carbon bisulphide. The light was oxy-hydrogen. Much light was lost, 
and the rays transmitted were chiefly yellow. 
It was found that if the system were made to coincide in direction with 
the plane of the magnetic meridian, the same position of the plane of polari- 
sation is not obtained by looking north or south, there being a difference of 
about between the two positions. When it was placed perpendicular to 
the magnetic meridian, the plane of polarisation was the same on looking 
east or west. 
It may be concluded that this rotation of the plane of polarisation is due 
to the action of the earth. Its direction is the same as that of the earth’s 
direction, and the same as that of an electric current which, on the hypo- 
thesis of Ampere, would give rise to the phenomena of terrestrial mag- 
netism. 
The apparatus described showed also great sensitiveness to the action of 
magnetism : an ordinary bar magnet held in the hand, and brought parallel 
to the tube, first in one direction, and then in the other, is sufficient to cause 
a rotation of the plane of polarisation of more than 1°. 
u It is interesting,” says M. Becquerel, “ to compare this direct measure- 
ment with an estimation by Mr. Gordon, in the ‘ Philosophical Transactions 
for 1877,’ of the magnetic rotation produced by 1 centim. of carbon bisul- 
phide under a magnetic action equal to unity. The result is that 2 5 metres 
should give with yellow light a single rotation of instead of 3'-25, 
which is the result of observation. 
