Prof. Troost published this profound solution in the forty-first volume of Silliman’s Journal; but in the forty-fourth of the same magazine a much more satisfactory one is given, for it is there stated “that the whole affair was a hoax devised by the negroes, who pretended to have seen the shower for the sake of practicing on the credulity of their masters. They had scattered the decaying flesh of a dead hog over the tobacco leaves.”[767] Another phenomenon to be particularly noticed in the history of the Butterflies, is their appearance at certain times in countless numbers migrating from place to place. H. Kapp, a writer in the _Naturforsch_, observed on a calm sunny day a prodigious flight of the Cabbage-Butterfly, _Pontia brassicæ_, which passed from northeast to southwest, and lasted two hours.[768] Kalm, the Swedish traveler, saw these last insects midway in the British Channel.[769] Lindley tells us that in Brazil, in the beginning of March, 1803, for many days successively there was an immense flight of white and yellow Butterflies, probably of the same tribe as the _Pontia brassicæ_. They were observed never to settle, but proceeded in a direction from northwest to southeast. No buildings seemed to stop them from steadily pursuing their course; which being to the ocean, at only a small distance, they must all have inevitably perished. It is to be remarked that at this time no other kind of Butterfly was to be seen, though the country usually abounds in such a variety.[770]