We are told by Prof. Ball that such is the translucency of nebulae one might think to be able to see through them the stars lying in the back-ground, were they in the right position for observation. If nebulae are thus translucent it does not seem possible that they can be composed of the same materials as the planets of the solar system, whose densities are generally so great. For were the whole of earth’s substance spread out to one-hundredth of an inch in thickness we can not believe it would be sufficiently clear to allow light to penetrate it to any great extent, as earth has a density that leads one to think it is centrally composed almost—if not wholly—of iron, lead, gold, or like weighty elements that seemingly would never be transparent however highly heated and expanded. But if the nebulae are similar to the planets in their substances they must then consist of enormous masses of luminous, heated matter in a highly diffused state, in order to be perceptible to us at so great a distance; and how can they be translucent if the coloring matter is retained to darken the gases that are in combustion? Material similar to that of earth, if highly diffused and placed in an element 300° below zero, would cool almost immediately; and whether luminous or not would be likely to obstruct our view of all stars lying behind it. We are told again by the same writer that doubtless there are hundreds, thousands, or even millions of dark bodies to each luminous one in space. But it has not been shown that these dark bodies ever needed to have been luminous in their formation, neither is it improbable that non-luminous matter,—even if once highly diffused, and spread out in the heavens as our sun is supposed once to have been diffused,—should have formed into these dark, spherical bodies in some manner similar to the condensation of vapor into clouds. If this be true the presumption is that the dark bodies are hiding many bright stars from our sight. It is not possible, then, to conceive that the many stars thus hidden—or partially hidden—may, like our sun when totally eclipsed, give a corona-like glow? Our own sun’s corona flames out in every direction for more than 200 thousand miles, and should there be many suns eclipsed by the dark bodies in space might they not likewise, in some instances, present a nebulous appearance with a startling coronal effect? Theta Orionis, the wondrous multiple star, seemingly lying in Orion’s great nebula, is regarded as belonging to it because of its being in the same degree of the heavens; but although in the same degree it may be in quite a different plane, as light travels at the rate of over eleven millions of miles per minute. If this nebula is unresolvable stars then the light from it may be millions of years in reaching us, while from Theta Orionis, if it lies in the foreground, the light might reach us possibly in one hundred years,—according to the distance it is removed from earth. The probabilities are