Sir Jagadis Chunder Bose | Page 4

the highest distinction that can be
conferred on a scientific man.

HIS FIRST SCIENTIFIC DEPUTATION. (1896-97)
The Government of India showed its appreciation of his work by
deputing him to Europe to place the results of his investigations before
the learned Scientific Bodies. He remained on his Deputation from the
22nd July 1896 to the 19th April 1897. He read a paper 'On a complete
Apparatus for studying the Properties of Electric Waves' at the meeting
of British Association, held at Liverpool, in 1896. He then
communicated a paper 'On the Selective Conductivity exhibited by
Polarising Substances,' which was published by the Royal Society, in
January 1897. He next delivered his 'Friday Evening Discourse,' at the
Royal Institution, 'On Electric Waves,' on the 29th January 1897.
"There is, however, to our thinking" wrote the Spectator at the time
"something of rare interest in the spectacle presented of a Bengalee of
the purest descent possible, lecturing in London to an audience of
appreciative European savants upon one of the most recondite branches
of the modern physical science." He was then invited to address the
Scientific Societies in Paris. "Prof. J. C. Bose" wrote the Review
Encyclopedique, Paris "exhibited on the 9th of March before the
Sorbonne, an apparatus of his invention for demonstrating the laws of
reflection, refraction, and polarisation of electric waves. He repeated
his experiments on the 22nd, before a large number of members of the
Academie des Sciences, among whom were Poincare, Cornu, Mascart,
Lipmann, Cailletet, Becquerel and others. These savants highly
applauded the investigations of the Indian Professor." M. Cornu,
President of the Academy of Science, was pleased to address Professor
Bose as follows:--
"By your discoveries you have greatly furthered the cause of Science.
You must try to revive the grand traditions of your race which bore
aloft the torch light of art and science and was the leader of civilization
two thousand years ago. We, in France applaud you." This fervent
appeal, we shall see, as we proceed, did not go in vain.
He was next invited to lecture before the Universities in Germany. At
Berlin, before the leading physicists of Germany, he gave an address on
Electric Radiation, which was subsequently published in the

Physikaliscen Gesellschaft Berlin, in April 1897.
FURTHER RESEARCHES ON ELECTRIC WAVES
Having received the most generous and wide appreciation of his work,
Dr. J. C. Bose continued, with redoubled vigour, his valuable
researches on Electric Waves. He studied the influence of thickness of
air-space on total reflection of Electric Radiation and showed that the
critical thickness of air-space is determined by the refracting power of
the prism and by the wave-length of the electric oscillations. He next
demonstrated the rotation of the plane of polarisation of Electric Waves
by means of pieces of twisted jute rope. He showed that, if the pieces
are arranged so that their twists are all in one direction and placed in
the path of radiation, they rotate the plane of polarisation in a direction
depending upon the direction of twists; but, if they are mixed so that
there are as many twisted in one direction as the other, there is no
rotation.[9] He communicated to the Royal Society the results of his
new researches. And the Royal Society published, in November 1897,
his papers 'On the Determination of the Index of Refraction of glass for
the Electric Ray' and 'On the influence of Thickness of Air-space on
Total Reflection of Electric Radiation' and, in March 1898, his further
contributions 'On the Rotation of Plane of Polarisation of Electric
Waves by a twisted structure' and 'On the Production of a "Dark cross"
in the Field of Electro-magnetic Radiation.'
SELF-RECOVERING "COHERER"
The study of Electric Waves by Dr. J. C. Bose led not only to the
devising of methods for the production of the shortest Electric Waves
known but also to the construction of a very delicate 'Receiver' for the
detection of invisible other disturbances. The most sensitive form of
detector hitherto known was the "Coherer." One of the forms made by
Sir Oliver Lodge consisted simply of a glass tube containing iron
turnings, in contact with which were wire led into opposite ends of the
tube. The arrangement was placed in series with a galvanometer and a
battery; when the turnings were struck by electric waves, the resistance
between loose metallic contacts was diminished and the deflection of
the galvanometer was increased. Thus the deflection of the

galvanometer was made to indicate the arrival of electric waves. The
arrangement was, no doubt, a sensitive one, but, to get a greater
delicacy, Dr. Bose used, instead of iron turnings, spiral springs which
were pushed against each other by means of a screw.[10] Still the
arrangement laboured under one great disadvantage. The 'receiver' had
to be tapped between each experiment. So