star from the sun. It is at that point that we think we see the star;
so here is a seeming displacement from the sun, which increases in the
measure in which the star is observed closer to the sun. The Einstein
theory teaches that the displacement is in inverse proportion to the
apparent distance of the star from the centre of the sun, and that for
a star just on its edge it will amount to 1'.75 (1.75 seconds). This is
approximately the thousandth part of the apparent diameter of the sun.

Naturally, the phenomenon can only be observed when there is a total
eclipse of the sun; then one can take photographs of neighboring stars
and through comparing the plate with a picture of the same part of
the heavens taken at a time when the sun was far removed from that
point the sought-for movement to one side may become apparent.

Thus to put the Einstein theory to the test was the principal aim of
the English expeditions sent out to observe the eclipse of May 29,
one to Prince's Island, off the coast of Guinea, and the other to
Sobral, Brazil. The first-named expedition's observers were Eddington
and Cottingham, those of the second, Crommelin and Davidson. The
conditions were especially favorable, for a very large number of
bright stars were shown on the photographic plate; the observers at
Sobral being particularly lucky in having good weather.

The total eclipse lasted five minutes, during four of which it was
perfectly clear, so that good photographs could be taken. In the
report issued regarding the results the following figures, which are
the average of the measurements made from the seven plates, are given
for the displacements of seven stars:

1''.02, 0''.92, 0''.84, 0''.58, 0''.54, 0''.36, 0''.24, whereas,