Page:Popular Science Monthly Volume 3.djvu/805

Rh interest was recently made at Cervetri, Italy, being a terra-cotta sarcophagus of native Etruscan production. The ancient Etrurians were noted for the honor they bestowed upon their dead, and their custom of paying homage to ancestors by placing their effigies upon their tombs seems to have been peculiar to themselves, and unknown among the Greeks. The recently-discovered sarcophagus is now in the British Museum. It measures internally four feet ten inches in length, and two feet in width. The floor is hollowed out, or rather marked by a raised border, which takes the form of a human figure. It rests upon four claw feet projecting beyond the angles, and terminating above in the head and breasts of a winged siren. The lid of the sarcophagus represents an upholstered couch upon which recline two human figures, male and female. There are inscriptions on the four sides of the couch. The panel at the foot has the figures of two warriors in panoply, and the front panel exhibits the same pair of warriors engaged in mortal combat. Several accessory figures are also to be seen. On the panel at the head of the couch are represented four sitting figures in opposing pairs, plunged in deep sorrow. The monument has no counterpart among those of its kind hitherto discovered, the only one at all resembling it being that of the Campana Collection in the Louvre. The latter is, however, of a much more recent date than the former, nor is it adorned with either reliefs or inscriptions. The Cervetri sarcophagus probably dates from the period of Etruscan ascendency in Italy.

Audible and Inaudible Sounds.—The phenomenon of color-blindness is a familiar fact; but an analogous phenomenon, what might be called pitch-deafness, though not uncommon, is not so generally known. By pitch-deafness is meant insensibility to certain sound-vibrations. Prof. Donaldson, of the University of Edinburgh, used to illustrate the different grades of sensibility to sound by a very simple experiment, namely, by sounding a set of small organ-pipes of great acuteness of tone. The gravest note would be sounded first, and this would be heard by the entire class. Soon some one would remark, "There, 'tis silent," whereas all the rest, perhaps, would distinctly hear the shrill piping continued. As the tone rose, one after another of the students would lose sensation of the acute sounds, until finally they became inaudible to all.

There is reason for supposing that persons whose ear is sensitive to very acute sounds are least able to hear very grave notes, and vice versa. Probably the hearing capacity of the human ear ranges over no more than 12 octaves. The gravest note audible to the human ear is supposed to represent about 15 vibrations per second, and the sharpest 48,000 per second.

The auditory range of animals is doubtless very different from that of man; they hear sounds which are insensible to us, and vice versa. Many persons are insensible to the scream of the bat—it is too acute. But to the bat itself that sound must be in all cases perfectly sensible. If, then, we suppose the bat to have an auditory range of 12 octaves, and its scream or cry to stand midway in that range, the animal would hear tones some six octaves higher than those audible to the human ear—two and a half million vibrations per second.

Scoresby and other arctic voyagers and whale-hunters have observed that whales have some means of communicating with one another at great distances. It is probable that the animals bellow in a tone too grave for the human ear, but quite within the range of the cetacean ear.

The Motions of the Heart.—According to the generally-accepted teachings of physiologists, the heart rests after each pulsation; that is, each complete contraction during which the auricles are emptied into the ventricles, and the ventricles into the vessels, is followed by a moment's repose, when the organ is entirely at rest. Dr. J. Bell Pettigrew, in his recently-published lectures on the "Physiology of the Circulation," takes a different view, affirming that the normal action of the heart is a continuous one, and that as a whole it never ceases to act until it comes to a final stop. He says: "When the heart is beating normally, one or other part of it is always moving. When the veins cease to close, and the auricles to open, the auricles begin to close and the ventricles to open; and so on