The climate of a city is, through causes dependent upon man, materially different from the natural climate of the surrounding country. Every dwelling provided with heating arrangements enjoys an artificial summer amid the blasts of winter. Local control of the winds is exemplified in the planting of thousands of miles of trees as windbreaks in the prairie regions of our Middle West. By moderating the winds this process has a marked effect on temperature and evaporation and is so beneficial to crops that in the aggregate it furnishes a striking example of successful “weather-making” by mankind. Analogous methods, perfectly feasible with means already at our disposal, would change the whole climatic aspect of large areas of the earth’s surface. The question “Can we make it rain?” may be answered in the affirmative by those who are neither impostors nor victims of self-delusion. The deposit of spray from the spout of a teakettle might, without much stretching of terms, be described as a miniature artificial rainstorm; but much bigger showers, in nowise different from those occurring in nature, can also be produced artificially. Huge clouds have often been observed to form over forest fires and other great conflagrations. These clouds, composed of water drops, tower far above the smoke cloud, and are identical in character and mode of origin with the cumulus and cumulo-nimbus clouds formed by currents of moist air rising from the heated ground on a summer day. There are several well-authenticated cases in which rain has been seen to fall from such clouds, and these showers have sometimes been so heavy as to extinguish the fires that generated them. Hence, given favorable conditions of humidity, temperature and wind, mankind can certainly produce a rainstorm (and perhaps a thunderstorm into the bargain) by the relatively simple process of building a big fire. Unfortunately the vast majority of methods whereby man has attempted to regulate the weather have no such rational foundation as those we have just mentioned. Some are wholly superstitious, others are purely empirical, and yet others are based upon ideas that their promoters suppose or pretend to be scientific, but that are actually fallacious.