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 through the finder, the little companion telescope, moved the roof a little more, made some further adjustments, and set the clockwork in motion. He took off his jacket, for the night was very hot, and pushed into position the uncomfortable seat to which he was condemned for the next four hours. Then with a sigh he resigned himself to his watch upon the mysteries of space. There was no sound now in the observatory, and the lantern waned steadily. Outside there was the occasional cry of some animal in alarm or pain, or calling to its mate, and the intermittent sounds of the Malay and Dyak servants. Presently one of the men began a queer chanting song, in which the others joined at intervals. After this it would seem that they turned in for the night, for no further sound came from their direction, and the whispering stillness became more and more profound. The clockwork ticked steadily. The shrill hum of a mosquito explored the place and grew shriller in indignation at Woodhouse's ointment. Then the lantern went out and all the observatory was black. Woodhouse shifted his position presently, when the slow movement of the telescope had carried it beyond the limits of his comfort.