against the attacks of the mosquitoes.

Even in these days of celestial photography, work done in a purely
temporary erection, and with only the most primitive appliances in
addition to the telescope, still involves a very large amount of cramped
and motionless watching. He sighed as he thought of the physical fatigues
before him, stretched himself, and entered the observatory.

The reader is probably familiar with the structure of an ordinary
astronomical observatory. The building is usually cylindrical in shape,
with a very light hemispherical roof capable of being turned round from
the interior. The telescope is supported upon a stone pillar in the
centre, and a clockwork arrangement compensates for the earth's rotation,
and allows a star once found to be continuously observed. Besides this,
there is a compact tracery of wheels and screws about its point of
support, by which the astronomer adjusts it. There is, of course, a slit
in the movable roof which follows the eye of the telescope in its survey
of the heavens. The observer sits or lies on a sloping wooden arrangement,
which he can wheel to any part of the observatory as the position of the
telescope may require. Within it is advisable to have things as dark as
possible, in order to enhance the brilliance of the stars observed.

The lantern flared as Woodhouse entered his circular den, and the general
darkness fled into black shadows behind the big machine, from which it
presently seemed to creep back over the whole place again as the light
waned. The slit was a profound transparent blue, in which six stars shone
with tropical brilliance, and their light lay, a pallid gleam, along the
black tube of the instrument. Woodhouse shifted the roof, and then
proceeding to the telescope, turned first one wheel and then another, the
great cylinder slowly swinging into a new position. Then he glanced