medium size, although it would be impossible of proof at this writing.
It would be interesting at this time to follow out the intellectual differences between these three races which we have described. The future social complexion of Europe is largely dependent upon them. The problem is too complicated to treat briefly. In a later paper, devoted expressly to modern social problems, we may return to it again. Our physical analysis is now complete. The next task is to trace the origin of nationalities from the combination of these elements. We shall begin with the French; for this single nation is, alone in all Europe, compounded of all three racial elements; nay, more, we shall be able to point to a still older population than any of these, living to-day in France, with an unbroken ancestry reaching back to the prehistoric stone age.
OCCASIONALLY in thunderstorms peculiar electrical apparitions occur, similar in destructiveness to ordinary lightning, but by no means so transient. Their duration is measured, not by thousandths of a second, but by whole seconds or even minutes. They move so slowly that their progress can be accurately followed by the eye. As they generally appear in the form of glowing spheres, they are known as fireballs or globe lightning. The first account of this peculiar form of lightning was given by the celebrated English physicist, Robert Boyle, who described a ball which suddenly appeared on July 24, 1681, on the ship Albemarle. The sailors attacked it in vain with blows and water, but it burned itself out, leaving behind a strong smell of gunpowder.
In Boyle's time ordinary lightning flashes were thought to consist of inflamed gas, so that an occurrence like the above did not appear particularly striking, but later investigators were unable to make the fireball fit their knowledge and theory of electricity, and declared it to be a myth. A layman stated that such a ball appeared in his room during a storm and slowly made its way to the chimney. The scientific people asserted that it was an illusion of the senses, and that there were no such things as fireballs. But the balls continued to appear, in some instances being simultaneously seen by a number of trustworthy witnesses, so that their existence had to be admitted.
Let us notice a few well-attested recent cases:
Dr. A. Wartmann has given the Physical Society of Geneva