As to the existence of water on the planet, one has only to consider the polar snow caps. In the height of the southern winter, the polar cap of snow measures over two thousand miles across, covering fifty-five degrees of latitude, with one unbroken waste of white. As spring advances the snow begins to melt, disappearing rapidly as summer comes on, and, as it melts, a dark band is seen bordering this edge. As the snow recedes the dark band recedes. This band is, therefore, not a permanent marking on the planet, but obviously water, the result of the melting snow--an arctic sea, in fact. This band is irregular, varying in width in different longitudes, as if the water filled up large areas of depression. When finally the snow cap disappears, as it did for the first time on record on the notable occasion of October 13, 1894, the dark band, which had become thinner, disappeared also, leaving only a yellow stretch of surface. An additional proof that this dark band is water, was established by Professor W. H. Pickering, for he discovered that the light reflected from its surface was polarized. The absurdity of the suggestion that these white polar caps are not snow, but congealed carbonic acid gas, is fully shown by Lowell. The asymmetry of the outline of these snow caps is paralleled by the irregularity of the Earth's polar caps. Glints of brilliant light are seen to flash out from this region, as if produced by sunlight reflected from a sloping surface. On comparing these flashes of light with observations made by Green, in 1877, they were found to be in the same place. Detached fields of snow were also observed below the receding line, an evidence that these regions were at a higher elevation. As before stated, on October 13, 1894, for the first time in the record of polar observations, the southern polar cap disappeared entirely. In this connection it may be of interest to observe that in the United States, in the summer of 1894, the temperature ranged a few degrees above the normal. (For this fact I am indebted to Professor Cleveland Abbe, E. S. M.)