The fact of change in the Martian markings forces itself upon any one who will diligently study the planet. He will be inclined at first to attribute it to observational mistakes of his own or his predecessor’s making, preferably the latter. But eventually his own delineations will prove irreconcilable with one another, and he will then realize the injustice of his inference and will put the cause, where indeed it rightly belongs, on the things themselves. Confronted by this fact he will the more fully appreciate how long and systematic must be the study of him who would penetrate the planet’s peculiarity. Just as the recognition of something akin to seasonal change came to Schiaparelli, because of his attending to the planet with an assiduity unknown to his predecessors; so it became evident that to learn the laws of these changes and from them the meaning of the markings, there was necessary as full and as continuous a record of them as it was possible to obtain. For this end it was not enough to get observations from time to time, however good these might be, but to secure as nearly as might be a complete succession of such, day after day, month after month, and opposition after opposition. The outcome justified the deduction. And it is specially gratifying to realize that to no one have the method and the results thus obtained appealed with more force than to Schiaparelli himself. Perseverance in scanning the disk long after the casual observer had considered it too far away for observational purposes, resulted in Schiaparelli’s detection of the canals, and this through a characteristic of theirs destined to play a great part in their history, their susceptibility to change. He tells us in his _Memoria I_ how Aeria and the adjoining regions showed blank of any markings while the planet was near in 1877 and the disk large and well shown, and then how, to his surprise, as the planet got farther away and the disk shrank, lines began to come out in the region with unmistakable certainty. Thus to the very variability which had hidden them to others was due in Schiaparelli’s hands their initial recognition.