The process of decay in clouds takes place in various ways. A careful observer may witness the gradual wasting away and dilution into thin air of even great stretches of cloud, when circumstances are favourable. In May 1896 my attention was particularly drawn to this at my manse in Strathmore. In the middle of that exceptionally sultry month, I was arrested by a remarkable transformation scene. It was the hottest May for seventy-two years, and the driest for twenty-five years. The whole parched earth was thirsting for rain. All the morning my eyes were turned to the clouds in the hope that the much-desired shower should fall. Till ten o'clock the sun was not seen, and there was no blue in the sky. Nor was there any haze or fog. But suddenly the sun shone through a thinner portion of the enveloping clouds, and, to the north, the sky began to open. As if by some magic spell there was, in a quarter of an hour, more blue to be seen than clouds. At the same time, near the horizon, a haze was forming, gradually becoming denser as time wore on. In an hour the whole clouds were gone, and the glorious orb of day dispelled the moisture to its thin-air form. This was a pointed and rapid illustration of the decay from cloud-form to haze, and then to the pure vapoury sky. It was an instance of the _reverse_ process. As the sun cleared through, the temperature in the cloud-land rose and evaporation took place on the surface of the cloud-particles, until by an untraceable, but still a gradual process through fog, the haze was formed. Even then the heat was too great for a definite haze, and the water-vapour returned to the air, leaving the dust-particles in invisible suspension. But clouds decay in another way. This I will illustrate in the next chapter on "It always rains." What strikes a close observer is the difference of structure in clouds which are in the process of formation and those which are in the process of decay. In the former the water-particles are much smaller and far more numerous than in the latter. While the particles in clouds in decay are large enough to be seen with the unaided eye, when they fall on a properly lighted measuring table, they are so small in clouds in rapid formation that the particles cannot be seen without the aid of a strong magnifying glass.