a considerable apparent space in the heavens. One of them is so bright, that the full moon does not obliterate it. They are very similar in structure to our galaxy; but there are innumerable nebulae embedded in the midst of them. The most common form is the spherical, but this shape is often due to the defect of optical power. What appears a perfect sphere with a small telescope, will often assume a most irregular figure under a larger power—the fainter portions not being discernible in the feebler instrument. We have, thus, ring nebulae, the crab nebula, the dumb-bell nebula, and various forms of spiral nebulae. The revelation of the spiral structure is due to the powerful telescopes of LordEosse; and the most interesting circumstance is, that this appears to be a very general character of the constitution of nebula. Our figure only illustrates the simpler form of the spiral, but, sometimes, eight or nine originate from one centre; and nebulae, hitherto supposed to be planetary, or presenting a uniform disc, are now resolved into an aggregate of many spirals, curiously combined.
Another curious feature has been discovered, very similar, apparently, to stratification. In the midst of the nebula long parallel bands are seen running along the whole length; these bands are perfectly black. The great nebula of Andromeda is a good illustration.
The recent revelations of the telescope have presented conditions and forms of forces to the astounded
