Climate, however, is one thing, weather another. The climate is the sum total of the weather. Climate is as enduring as our Constitution, the weather is as changeable as our city governments. No matter how proud a scientist may be of the lasting qualities of the climate, he has to admit that our weather, taken day by day or even year by year, is versatile in the extreme. And the question he has set himself to solve is how to explain the variations of the seasonable weather. He wants to find out why all winters are not alike, and why no two successive springs are the same. Then he will be on firm ground at last and able to make scientific forecasts for the ensuing year. The obvious thing was to find out as accurately as possible what had happened and science's keenest eye was focused on records in the hope of discovering fixed periods of warmth or wetness, cycles of cold and drought. So far no cycles have been discovered that are beyond dispute. Nothing has been found that cannot be contradicted successfully. This is discouraging. One of the most frequent starting places for investigators is the spots on the sun. They found that periods of three, eight, eleven, and thirty-five years should bear some resemblance; 1901 was eagerly looked forward to. They wanted it to correspond with the remarkably cool summer of 1867. When it started off in July with a temperature of 103 degrees, the highest ever recorded in Philadelphia, they concluded that the sunspots were fooling them. A connection between sunspots and weather has not been established, therefore, although they are now known to affect the electrical condition of the earth's atmosphere. Longer periods of observation will permit comparisons that may yet define concurrent cycles of sunspots and weather. A definite weather cycle has not yet been discovered, but one step in the way has been cleared up. We now are pretty sure of one cause for unusual single seasons of heat and cold. There exist in winter great bodies of cold, dry air heaped up over Canada and Siberia, which are formed by the greater rapidity of radiation over land surfaces than over water. These mounds of cold air build up during December, January, and February and form great so-called permanent areas of high barometer. It is on the skirts of the Canadian high that the smaller highs form which sweep over our country, giving us our cold waves. Also in winter permanent lows form over the North Pacific and North Atlantic where warm currents afford continuous supplies of warm moist air. From the great Aleutian (Pacific) low spring most of the cyclones which swing down below the border of the Canadian high, make their turn somewhere in the Mississippi Valley, and then head for the Icelandic low.