g
the average of the best series of observations, the deflection at
the sun's limb is found to be 1.98'', with a probable error of about
6 per cent., whereas the deflection calculated by Einstein's theory
should be 1.75''. It will be noticed that Einstein's theory gave a
deflection twice as large as that predicted by the orthodox theory,
and that the observed deflection is slightly larger than Einstein
predicted. The discrepancy is well within what might be expected in
view of the minuteness of the measurements. It is therefore generally
acknowledged by astronomers that the outcome is a triumph for Einstein.

(3) In the excitement of this sensational verification, there has
been a tendency to overlook the third experimental test to which
Einstein's theory was to be subjected. If his theory is correct as it
stands, there ought, in a gravitational field, to be a displacement
of the lines of the spectrum towards the red. No such effect has
been discovered. Spectroscopists maintain that, so far as can be
seen at present, there is no way of accounting for this failure if
Einstein's theory in its present form is assumed. They admit that some
compensating cause may be discovered to explain the discrepancy, but
they think it far more probable that Einstein's theory requires some
essential modification. Meanwhile, a certain suspense of judgment
is called for. The new law has been so amazingly successful in two
of the three tests that there must be some thing valid about it,
even if it is not exactly right as yet.

Einstein's theory has the very highest degree of aesthetic merit:
every lover of the beautiful must wish it to be true. It gives a
vast unified survey of the operations of nature, with a technical
simplicity in the critical assumptions which makes the wealth of
deductions astonishing. It is a case of an advance arrived at by
pure theory: the whole effect of Einstein's work is to make physics
more philosophical (in a good sense), and to restore some of that
intellectual unity which belonged to the great scientific systems of
the seventeenth and eighteenth centuries, but which was lost through
increasing specialization and the overwhelming mass of detailed
knowledge. In some ways our age is not a good one to live in, but
for those who are interested in physics there are great compensations.

THE EINSTEIN THEORY OF RELATIVITY

A Concise Statement by Prof. H. A. Lorentz, of the University of Leyden

The total