The dry “hot winds” that sometimes wither the crops of our western plains are the American antithesis of the blizzard. These winds belong to the great sirocco family--the name “sirocco” having become, in recent scientific usage, a generic designation for extensive hot winds, whether dry or moist, as distinguished from local hot winds, such as the foehn. The _harmattan_ of West Africa is a dry, dusty wind from the Sahara, and one that feels relatively cool; perhaps on account of causing rapid evaporation from the skin. The _simoom_ (with a final _m_), especially the variety blowing in southern Asia, is perhaps the hottest and most parching of all winds--judging from its effects on animal life. The great majority of the winds above enumerated are merely minor features of what are called _cyclonic_ and _anticyclonic_ wind systems. Reverting to what has been said about weather maps and Buys Ballot’s Law--if the reader will examine a series of maps for successive days, he will notice that the areas of high pressure and low pressure are not stationary, but show a more or less rapid displacement, the general direction of which, in our latitudes, is from west to east. The fact that there are great traveling vortices or swirls in the atmosphere, which, in whatever regions they occur, partake of the general drift of the air around the globe, has been known for about a century, and constitutes the corner stone of practical meteorology. In the temperate zone, where these swirls are sometimes of moderate force and sometimes very stormy, they are the chief factor in controlling changes of weather from day to day, and their observation is the basis of weather forecasting. Within the tropics, where they are much less frequent and are confined to a few restricted regions, they are always violent storms. An area of high pressure, with its attendant system of winds, is called an _anticyclone_ or _high_. An area of low pressure, with its winds, is called a _cyclone_--sometimes. The word “cyclone” was invented by Henry Piddington in the year 1848. Nearly all the early studies of cyclones were made chiefly for the benefit of mariners, and related to the severe revolving storms encountered at sea. Hence the word “cyclone” passed into the general vocabulary with a connotation of violence, which, in everyday speech, it still retains. Perhaps the early “cyclonologists” themselves hardly realized that a “gentle cyclone” was not a contradiction in terms.