Among the popular superstitions which the almost general illumination of modern times has not been able t o obliterate, the d re ad of the death watch may well be considerud as one of the most predominant; yet it must be allowed to be a very singular circumstance that an animal so common should not be more universally known, and the peculiar noise which it occasionally makes be more universally understood. The insect, an engraving of which we present herewith, in question, is a small beetle belonging to the timber-boring genus, Ano-bium, and the popular superstition alluded to is, that when its beating is heard, it is a sign that some one in the house will die before the end of the year. It is chiefly in the advanced state of spring that this little creature commences its sound, which is no other than the call or signal by which the male and female are led to each other, and which may be considered as analogous to the call of birds; though not owing to the voice of the insect, but to it s beating on, or striking, any hard substance with the shield or forepart of the head. The prevailing number of distinct strokes which it beats is from seven to nine or eleven; and this very circumstance may perhaps still add to the ominous character which it bears among the vulgar. These sounds or beats are given in pretty quick succession, and are repeated at uncertain in Invention of the Spirit Level. He who first filled a glass bottle with a liquid, leaving a small quantity of air therein to form a bubble, then corked the bottle and laid it flat on one side, with the bubble floating against the upper part was the unconscious inventor of the, spirit level, which is a very simple instrument in appearance, but of th e utmost value, when properly made, to the astronomer, the engineer, and the builder; for when the bottle is placed horizontally, the bubble always mounts to, and rests at its most elevated point; and the tangent to that point, when the middle or apex point of the bubble coincides therewith, is a horizontal line ; that is a line at right angles, or perpendicular to the direction of gravity or the plumb line passing through that point. This was first perceived and applied, so far as is known, in France in 1666, by Melchisedec Thevenot, who was a great amateur of science and a writer of books of voyages and travels. In this respect he enriched the literature of France as much as Hakluyt enriched that of England half a century earlier. It was at Thevenots house that the learned men who founded the Academy of Sciences of Paris used to assemble ; and it was at one of their meetings that he propounded the spirit level. A description of the instrument, accompanied with figures, was first published in the Journal des Savants, Paris, November 15, 1666, under this title :Machine nouvelle pour la con-duite des eaux, pour les bdtiments, pour la navigation, tt pour la plupart des autres arts.» The instrument is there called an air level; and is described as a glass tube, hermetically sealed at both ends, containing spirits of wine, which do not freeze, and a small quantity of air forming a bubble. It is stated that the instrument is cap able of giving, with much exactness, the direction of the ho.zon, the^perpendicular to the horizon,and vertical angles; and that it is easier to make,more convenient to use, and indicates a level line more readily and accurately than any other instrument. The Colorado Expedition. The expedition under the command of Col. Powell, the Col orado explorer, has returned to Chicago, having successfully traveled through the entire Grand Canon, from Green River to the point where the Colorado debouches into the open plain in the territory o f Alrizona. From the point where Colonel Powells last letter was writ-len the expedition descended the river about four hundred miles, between walls almost vertical, ranging from five hundred to one thousand five hundred feet high, the exterior of the canon being from two thousand five . hundred to foal thousand feet above the bed of the river. More than two hundred waterfalls and cascades, emptying themselves over the walls of the canon into the main river, were seon in this distance, with almost every variety of natural scenery. The geological formation of the canon consists principally of limestone and sandstone ; granite is only found at three places?-and in a limited amount. No discoveries of precious metals were made, and there were no indications of gold or silver found in the bed of the river. One section of the canon was found to consist of a very fino 1869 SCIENTIFIC AMERICAN, INC. 230 [October 9, 1869. beatifully-polished marble, which at present is entirely inaccessible. The country traversed was barren beyond description, and is pronounced by Colonel Powell as not susceptible of cultivation, even by irrigation.
This article was originally published with the title "Death Watch—Natural Size and Magnified"