Page:Gods Glory in the Heavens.djvu/283

Rh fire would be quite destructive of nice observation. An artificial eye would, then, be an acquisition of no ordinary value. This idea, although it savours of the wild conception of Frankenstein, is already partially realised. The artificial eye consists of a surface sensitive to light, placed where the eye of the observer is now placed, and the image of the celestial object is drawn at any moment on this surface, instead of on the retina of the observer. The difference is, that the impression on the artificial eye is permanent, and we can examine it at our leisure, whereas the impression on the living eye is transitory, and we have to depend on a hurried, and perhaps erroneous report. An apparatus is erected at Kew Observatory on this principle, for the observation of the sun's disc. To gain this object, it is so arranged by clock-work that an artificial retina is presented at a certain moment, and after receiving the photographic image withdrawn. This plan has had only partial success; but we can readily conceive it to be so developed as to work a revolution in astronomy.

After examining the transit-room, the visitor will be ushered into the dome, where the equatorial instrument is fixed on a pillar. The dome, of sheet-iron, is a very conspicuous object for miles around. It serves no other purpose than that of a convenient shelter for the telescope. The equatorial, unlike the transit instrument, is made to turn in every direction.