of a
century; still it was the quickest moving star then known. The position
of this interesting double he compared with two other stars which were
seen simultaneously in the field of the heliometer, by the method I have
described, throughout the whole year 1838; and in the last month of that
year he was able to announce with confidence a distinct though very
small parallax; substantiating it with a mass of detailed evidence which
commanded the assent of astronomers. The amount of it he gave as
one-third of a second. We know now that he was very nearly right, though
modern research makes it more like half a second.[29]

Soon afterwards, Struve announced a quarter of a second as the parallax
of Vega, but that is distinctly too great; and Henderson announced for
[alpha] Centauri (then thought to be a double) a parallax of one
second, which, if correct, would make it quite the nearest of all the
stars, but the result is now believed to be about twice too big.

Knowing the distance of 61 Cygni, we can at once tell its real rate of
travel--at least, its rate across our line of sight: it is rather over
three million miles a day.

Now just consider the smallness of the half second of arc, thus
triumphantly though only approximately measured. It is the angle
subtended by twenty-six feet at a distance of 2,000 miles. If a
telescope planted at New York could be directed to a house in England,
and be then turned so as to set its cross-wire first on one end of an
ordinary room and then on the other end of the same room, it would have
turned through half a second, the angle of greatest stellar parallax.
Or, putting it another way. If the star were as near us as New York is,
the sun, on the same scale, would be nine paces off. As twenty-six feet
is to the distance of New York, so is ninety-two million miles to the
distance of the nearest fixed star.

Suppose you could arrange some sort of telegraphic vehicle able to carry
you from here to New York in the tenth part of a second--_i.e._ in the
time required to drop two inches--such a vehicle would carry you to the
moon in twelve seconds, to the sun in an hour and a quarter. Travelling
thus continually, in twenty-four hours you would leave the last member
of the solar system behind you, and begin your plunge into the depths of
space. How long would it be before you encountered another object? A
month, should you guess? Twenty years you must journey with that
prodigious speed before