say, after the original message was sent. Washington is at once
notified of this double transmission interval. On the assumption
that HALF of it represents the time the message took to travel from
east to west, and the other half the time from west to east again,
the Washington chronometer is set one second ahead of the signalled
time, to compensate for its part of the loss. When the sun has
reached the meridian of Washington, the whole process is repeated,
and again as before, half of the time the message has taken to cross
and recross the Atlantic is added to the Greenwich record of noon at
Washington. The number of hours, minutes, seconds, and fractions of
a second between these two corrected records represents the
difference in solar time between the two places, and incidentally
the same moment of time has been established for both--at least, so
it would appear.

But is it established? That each message took an equal time to
travel each way is pure assumption, and happens to be a false one.
The accuracy of the result is vitiated by a condition of things to
which the Relativists have called attention. Our determination might
be defended if Washington and Greenwich could be assumed to remain
at rest during the experiments, and some argument might even be made
in its favor if we could secure any cosmic assurance that the
resultant motion of the earth should be the same when Greenwich
signalled its noon to Washington and Washington its noon to Greenwich.

Our present discussion is merely illustrative, or diagrammatic; so
we will neglect the velocity of the earth in its orbit round the sun,
some forty times greater than that of a cannon ball, and the more
uncertain and more vertiginous speed of the whole solar system
towards its unknown goal. Let us consider only the rotation of the