As a side argument it is suggested that the smoke of the burning woods, or few years ago in Michigan, caused as peculiar condition of the atmosphere. This extensive fire was on a day when the area of low barometer was on a high line of latitude and passing to the eastward. This naturally took the smoke, which is far lighter than dust, along with it. It mingled with the muggy condition of an extensive "low," and produced a yellowness of the atmosphere. This however was of only a few hours' duration, and was only visible in favorable localities. Here again we see the advantage of the weather maps; but for this map we would never have been able to have satisfactorily explained the peculiar phenomenon produced by the great Michigan fire. If the delicate redness of the sky is not caused by dust, what is it caused by? But for the weather map, I think we should still be in the dark in regard to it. In the first place, this redness is nothing new, only the conditions are more favorable sometimes than at others. It has always existed and always will exist, independent of earthquakes, volcanoes, etc. Nature is ever changing; the movements of the atmosphere more resemble the kaleidoscope than any thing else. The summer and fall of 1883, the movements of "high" (high barometer) over the United States were quite central and extensive, causing this peculiar phenomenon over a wide extent of territory. We have no information of the condition of the barometer over the other part of the world; we speak move particularly of the United States; yet if certain conditions produce certain effects here, it is quite safe to say that the same effects are produced by the same cause elsewhere. As now well established by the map, the surface wind is from the area of high barometer to that of low--from the atmospheric hill to the atmospheric valley. The tendency of this is to free "high" of all clouds and moisture; but then it is impossible to free "high" entirely of moisture; a little will remain, and it is just this little, which is highly rarefied, that produces the result. We look around us and above, we see little or no evidence of evaporation, yet it is the while going on. When the sun is immediately below the horizon, where it will shine horizontally through the mass of light, suspended moisture, the delicate presence of vapor heretofore unnoticed is revealed. The action of the sun's rays is the same as when illuminating a well formed cloud--it is an embodiment of the same principle, but the material is much more expanded. The particles of suspended moisture are very fine, few and far between, therefore the effect of the light upon it is more diffused and transparent. It is much like looking through a piece of window glass flatwise and endwise; flatwise we do not perceive any color; endwise, from seeing through a greater mass, the glass has a very perceptible green color.