Quite the other extreme would be the conditions on the dark side, for without the sheltering blanket of an atmosphere, this surface must be exposed to the intense cold of interplanetary space. I have reason to believe, however, particularly from my deductions made in connection with the photographs taken during the transit of Mercury over the face of the sun on November 11 last, that there does exist an atmosphere on this planet--an atmosphere that appears to be denser and more cloudy than our own. I am led to this conclusion by other evidence that has long been fairly generally accepted as fact. The terminating edge of the phases of Mercury is not sharp, but diffuse and shaded--there is here an atmospheric penumbra. The spectroscope also shows lines of absorption, which proves that Mercury has a gaseous envelope thicker than ours. This atmosphere, whatever may be its nature I do not assume, tempers the heat and cold on Mercury to a degree comparable to the earth. But I do believe that it makes the planet--on its dark face particularly--capable of supporting intelligent life of some form. Mercury was in transit over the face of the sun on November 11, of last year, within a few hours of the time the first meteor fell to earth. The planet was therefore at one of her closest points to the earth, and--this is significant--was presenting her _dark face_ toward us. At this time several new "stars" were reported, flashing into brilliancy and then fading again into obscurity. All were observed in the vicinity of Mercury; none appeared elsewhere. I believe these so-called "stars" to be some form of interplanetary vehicle--probably navigated in space by beings from Mercury. And from them were launched the two meteors that struck our planet. How many others were dispatched that may have missed their mark we have no means of determining. The days around November 11 last, owing to the proximity of Mercury to the earth, were most favorable for such a bombardment. A similar time is now once more almost upon us! Because of the difference in the velocities of Mercury and the earth in their revolutions around the sun, one synodic revolution of Mercury, _i.e._, from one inferior conjunction to the next, requires nearly one hundred and sixteen days. In eighty-eight days Mercury has completed her sidereal revolution, but during that time the earth has moved ahead a distance requiring twenty-eight days more before she can be overtaken. After the first week in March of this year therefore Mercury will again be approaching inferior conjunction, and again will pass at her closest point to the earth. We may expect at this time another bombardment of a severity that may cause tremendous destruction, or destroy entirely life on this planet! CHAPTER II. THE UNKNOWN ENEMY.