On the 7th May, 1822, some remarkable hailstones fell at Bonn, on the Rhine. Their general size was about an inch and a half in diameter, and their weight 300 grains. When picked up whole, which was not always the case, their general outline was elliptical, with a white, or nearly opaque spot in the centre, about which were arranged concentric layers, increasing in transparency to the outside. Some of them exhibited a beautiful star-like and fibrous arrangement, the result of rows of air bubbles dispersed in different radii. The figures at the head of this chapter show the external and internal appearances of these hailstones. The smaller figures represent pyramidal hail, common in France, and occasionally in Great Britain. Brown hailstones have been noticed. Humboldt saw hail fall of the colour of blood. On the 15th July, 1808, Howard noticed, in Gloucestershire, hailstones from three to nine inches in circumference; appearing like fragments of a vast plate of ice which had been broken in its descent to the earth. On the 4th June, 1814, Dr. Crookshank noticed, in North America, hailstones of from thirteen to fifteen inches in circumference. They seemed to consist of numerous smaller stones fused together. On the 24th July, 1818, during a storm in Orkney, Mr. Neill picked up hailstones weighing from four ounces to nearly half a pound. [Picture: Rain gauges] CHAPTER V. METHOD OF MEASURING THE QUANTITY OF RAIN THAT FALLS—THE RAIN GAUGE—METHODS OF OBSERVING FOR RAIN AND SNOW—EFFECTS OF ELEVATION ON THE QUANTITY OF RAIN—DIFFERENCE BETWEEN THE TOP OF A TALL BUILDING AND THE SUMMIT OF A MOUNTAIN—SIZE OF DROPS OF RAIN—VELOCITY OF THEIR FALL—QUANTITY OF RAIN IN DIFFERENT LATITUDES—EXTRAORDINARY FALLS OF RAIN—REMARKS ON THE RAIN OF THIS COUNTRY—INFLUENCE OF THE MOON—ABSENCE OF RAIN—REMARKABLE DROUGHT IN SOUTH AMERICA—ITS TERRIBLE EFFECTS AND CONSEQUENCES—ARTIFICIAL RAINS.