When the auricula is brought forward, all acute sounds are rendered much more intense, but no sensible difference is [p072] perceived with regard to the grave sounds. The higher tones of glass staccados, or of an octave flute, the ticking of a watch, all kinds of sibilant sounds, &c. are thus greatly augmented: the experiment is easily tried, by whistling very shrill notes. A still greater augmentation of the acute sounds is obtained, by placing the hands formed into a concave behind the ears, and by bending downwards the upper part of the auricula, so as to obtain a more complete cavity.
§ 6.
I will conclude with the following observation: I had, in consequence of a cold, a very slight pain in my left ear; on sounding the regular notes of the piano-forte, C3 and C4 were much louder than the others, and the loudness was much increased, by placing the hand in the manner above described to the left ear. When it was pressed close, or when the Eustachian tube was closed, the intensities of all the notes were equalized. I attribute this affection to the diminished tension of the membrana tympani, which was again increased by the operation described.
[23] Recherches sur les usages de la membrane du tympan et de l’oreille externe; par M. Felix Savart. Annales de Chimie, tom. xxvi. p. 1.
[24] The tuning-fork consists of a four-sided metallic rod, bent so as to form two equal and parallel branches, having a stem connected with the lower curved part of the rod, and contained within the plane of the two branches. The branches are caused to vibrate by striking one end against a hard body, whilst the stem is held in the hand. The sound produced by this instrument when insulated is very weak, and can only be distinctly heard when its branches are brought close to the ear; but instantly its stem is connected with any surface capable of vibrating, a great augmentation of sound ensues from the communicated vibrations. The facility of its insulation and communication renders it a very convenient instrument for a variety of acoustical experiments.
On the Petromyzon Marinus. [◊]
ON entering the harbour of Dublin a few weeks ago, we were becalmed off the Hill of Howth, and to pass the tedious time until a breeze sprung up, we found some lines on board, and began to fish from the quarter-deck. We caught a number of grey gurnet; but our attention was particularly attracted by a pull of uncommon force on one of the lines. Having rendered assistance to the person who held it, we were all astonished to see rise out of the water a large fish, with apparently a double body, which, after floundering on the surface of the water, we pulled on deck. On examining this phenomenon for a short time, we were again surprized to see it separate into two parts; and then found that there were two large fish taken up on the same hook, the head of one having been buried under the throat of the other, to which it had firmly attached itself. When separated by force, it wiggled about on the deck with extraordinary strength and agility, and again darted on its prey, to which [p073] it adhered so firmly, that it required very considerable exertion to detach it; for it suffered itself to be raised up by the tail, and shaken, still holding the other fish suspended from its jaws. When finally separated, it showed great ferocity, darting at every thing near it, and at last seizing the deck, which it held very fast, writhing with its tail and body as if in the act of tearing it to pieces. When detached, its teeth left a deep circular impression on the wood, the fibres of which were drawn into the cavity of its jaws, so as to be raised up in the form of a cone. I now directed, that it should be put into a bucket of sea water, in the hope of preserving it alive until we arrived in Dublin, but it died in a shorter time than could be expected, from the energy and activity it had displayed, long after the other fish was dead. We had handled it very roughly, and so perhaps had mortally hurt an animal otherwise very tenacious of life.
On examining the fishes, I found that which had taken the hook, was the gadus Polachius, or whiting Pollack. It was about two feet long, and it is probable its active enemy had fastened [p074] on it after it had been hooked; if before, it would indicate an extraordinary insensibility to pain in an animal that could attend to the calls of appetite, whilst another was preying on its vitals. The fish which had fastened on the pollack, was the petromyzon marinus, or sea lamprey. It was nearly three feet long, and resembled a large eel in shape. Its general colour was a dull brownish olive variegated with bluish blotches; the back darker, and the belly paler, inclining to yellow. The eyes were small, and the mouth large and oval; but when distended, circular. The inside of the jaws was deeply concave, and studded with circular rows of sharp triangular teeth, that issued from corresponding orange-coloured papular protuberances, which formed the gums; the tongue was short and crescent-shaped, furnished with a row of very small teeth round the edge. On the top of the head was a small orifice, or spout-hole, from whence it discharged the superfluous water taken at the mouth. But the circumstance that more particularly distinguished it, was that which gave rise to the vulgar error that it had sixteen eyes. On either side of the neck, commencing just below the real eyes, was a row of seven equidistant spiracles exactly resembling eyes; they are, however, holes lined with a red membrane, and all opening into the mouth, an apparatus to supply the place of gills, whose functions are to extract oxygen from the water, and so perform the office of lungs in aquatic animals. It had two dorsal fins, one on the lower part of the back, narrow, with a roundish outline; the other commencing where the first terminated. The spine was cartilaginous, without processes. The pericardium, containing a small heart, was a remarkably strong membrane, and the liver was as green as grass.
This fish is not uncommon in the North Seas, though it most abounds in the Mediterranean, where, from earliest times, it was esteemed a luxurious dish. Fish-ponds were purposely constructed to preserve it. On our coast, Pennant observes, that it is found most frequently at the mouth of the Severn, which river it sometimes ascends, where it is occasionally taken, firmly attached to a stone by its mouth, while its tail and body are waving freely to the current. Its adhesion at such times is so strong, that it may be lifted with a stone of twelve pounds weight appended to its mouth. This faculty is owing to its [p075] power of suction; while the circumstance of its circular jaws coming in close contact with the surface of the body excludes the external air within the cavity of the mouth, and so adheres like the hand placed on the cup of an air-pump. It is from this remarkable property, that its scientific name has been imposed[25]. Its vulgar name, lamprey, from lampetra, has a similar derivation. By the Romans it was named muræna. As this fish was well known and highly prized by the ancients, there is none that has been so frequently described and alluded to. Aristotle, Pliny, Tacitus, Columella, Ælian, Seneca, and Oppian, have mentioned its properties and habits, which correspond exactly with those I have described above. Pliny says, in the northern parts of France, and consequently contiguous to the British Isles, the lampreys have seven spots in the jaws, resembling the constellation of the plough, evidently the same as the eyes, which vulgar opinion assigns to the fish[26]. Their extreme voracity was such, that criminals were thrown among them to be devoured. Seneca relates, that Vedius Pollio, a Roman knight, ordered his servant, who had broken a crystal vase, to be thrown into a large pond of lampreys[27]; and Columella writes, that they were sometimes seized with a rabid fury, that resembled canine madness; in the access of which, they seized upon other fish, so that it was impossible to keep them in the same pond[28]; and to account for this extraordinary ferocity, Oppian and others assert, that the lamprey is impregnated by a serpent; the one issuing from the sea, and the other rushing down to the rocks, inflamed with madness, to consummate the impregnation; and adds, that the extraordinary intercourse was effected by the lamprey seizing the serpent’s head in its [p076] mouth[29]. This singular copulation was the reason why the Romans, who were immoderately fond of lampreys, did not wish to eat them, when impregnated by the supposed serpent. Horace, therefore, makes Nasidienus, among the blunders of his supper, serve it in that state[30].