The second result afforded by the cartouches is not of a destructive, negative character,—however valuable the destruction of bars to knowledge may be,—but of a constructive, positive one. It does not, like the first, follow from mere inspection, but is brought to light only by comparison of all the cartouches. In a positive way, therefore, its testimony is as conclusive as it was in a negative direction. For that 10,900 separate and independent data should result in a general law of development through either conscious or unconscious bias, when those data would have to be combined in so complicated a manner for the result to emerge as is here the case, is impossible. Chance could not do it and consciousness would require a coördinate memory, to which Murphy’s nine games of chess at once would be child’s play. Of the 109 canals examined 106 showed by their cartouches that they had been during the whole or a part of the period in a state of change. But the change was not the same for all. In some the minimum came early; in others, late. Some decreased to nothing and stayed there; others increased from zero and were increasing still at the time observations closed. Latitude proved the means of bringing comparative order out of the chaos. When the canals were ranged according to their latitude on the planet, a law in their development came to light. To understand it, the circumstances under which the canals were presented must be considered as regards the then season of the planet’s year. In 1903 the planet passed on February 28 through the point of its orbit where the summer solstice of the northern hemisphere occurs. One hundred and twenty-six days later took place the first snowfall in the arctic and subarctic regions, an event that denoted the beginning of the new polar cap; from which date the snow there gradually increased. Its autumnal equinox the planet did not reach till August 29. Now, the canals were observed from thirty-six days before the summer solstice of the northern hemisphere to one hundred and forty-seven days after that event. We may tabulate the dates as follows:— ================+===========+================ DAY FROM | VERNAL | CORRESPONDING SUMMER SOLSTICE | LONGITUDE | DATE ON EARTH ----------------+-----------+---------------- -30 | 77° | June 9 0 | 90° | June 22 +30 | 103° | July 6 +60 | 117° | July 20 +90 | 131° | August 4 +120 | 146° | August 20 +150 | 162° | September 5 ================+===========+================ The vernal longitude is the longitude of the planet in its orbit reckoned from the vernal equinox. From the table it appears that the cartouches cover the development of the canals from about June 6 to September 1 of the Martian northern hemisphere for the current but to us undated year, _ab Marte condita_.