Leslie supposes the effect of the trumpet to be owing to the more condensed and vigorous impulsion given to the air from its lateral flow being checked. He observes, “that the tube, by its length and narrowness, detains the efflux of air, and has the same effect as if it diminished the volubility of that fluid, or increased its density. The organs of articulation strike with concentrated force, and the pulses, so vigorously thus excited, are, from the reflected form of the aperture, finally enabled to escape and to spread themselves along the atmosphere247.”]
FOOTNOTES
224 Goguet. i. p. 326.
225 Plin. lib. xvi. c. 38, p. 32.
226 Septalii Comm. in Aristotelis Problem. Lugd. 1632, fol. p. 206. There is also a passage to the same purpose in Seneca, Epist. 108.
227 See Anciennes Relations des Indes et de la Chine, de deux voyageurs Mahometans, qui y allèrent dans le neuvième siècle. Par Renaudot. Paris, 1718, 8vo, p. 25.
228 Ars magna lucis et umbræ. Amst. 1671, fol. p. 102. Kircher repeats this account with some new circumstances in his Phonurgia, p. 132.
229 Morhofii Diss. de vitro per vocis sonum rupto, in Dissertationibus Academicis. Hamburgi 1669, 4to, p. 381.
230 Morhof quotes the following passage:—“With this brazen horn, constructed with wonderful art, Alexander the Great called together his army at the distance of sixty miles. On account of its inestimable workmanship and monstrous size, it was under the management of sixty men. Many kinds of sonorous metals were combined in the composition of it.”
231 “Among many things which the celebrated D’Alance caused to be made for this purpose, the trumpet ascribed to Alexander, and with which he called together his army, ought not to be omitted. As the figure of it was represented in an old manuscript in the Vatican library, and had been described by Bettini, that learned man was desirous of trying whether it could be proved by experience, and the attempt succeeded; for that kind of trumpet, if it does not excel, seems undoubtedly to equal the other instruments constructed for that end.”
232 Bettini Apiaria univ. Philosophiæ Mathemat. Bonon. 1642, fol. p. 38.
233 Magia Natural. lib. xx. c. 5.
234 “To communicate anything to one’s friends by means of a tube. This can be done with a tube made of earthenware, though one of lead is better, or of any other substance, but very close, that the voice may not be weakened; for whatever you speak at the one end, the words issue perfect and entire as from the mouth of the speaker, and are conveyed to the ears of the other, which, in my opinion, may be done for some miles. The voice, neither broken nor dispersed, is carried entire to the greatest distance. We tried it at the distance of two hundred paces, not having convenience for a greater, and the words were heard as clearly and distinctly as if they had come from the mouth of the speaker.”—Lib. xvi. c. 12.
235 Mathematische Erquickstunden, i. p. 243.
236 An Account of the Speaking-trumpet, as it hath been contrived and published by Sir Samuel Morland, knight and baronet, together with its use both at sea and land. London, 1671. An extract from it may be seen in the Phil. Trans., No. 78, p. 3056.
237 Among the antiquities of Syracuse in Sicily, one beholds with wonder chambers and galleries which are hewn out in the solid rock, and particularly a grotto, from which arises a winding passage, that becomes upwards still narrower. Ancient tradition says that this was a prison, which the celebrated tyrant Dionysius caused to be built for state prisoners, that in an apartment of his palace, which stood over the narrow end of the passage, he might hear everything the prisoners said, or what plots they formed against him. This grotto therefore is called Orechio di Dionysio, or la grotta della favella; auris Dionysii, the ear of Dionysius. Many travellers and others formerly imagined that this passage was an ingenious imitation of that part of the human ear called the helix, which was first remarked by Alcmaon the Pythagorean. This is the account given by Kircher, who was there in the year 1638. See his Phonurgia (published 1673), p. 82, where there is a figure of it. In later times, however, this grotto has been examined with more skill and acuteness by people less subject to prejudice, and since that period the supposed wonder has been lessened. The rock consists of limestone, at least I conclude so from what is said by Brydone, who found it everywhere full of cracks and fissures. The stones of which Syracuse was built were hewn from the rock; and hence have been formed these chambers or openings, like those found in the neighbourhood of other ancient and modern cities, such as Rome, Naples, and Maestricht. Many of these, in the course of time, have been employed as prisons, or used as burying-vaults. The above-mentioned passage, which has excited so much wonder, is not properly spiral, and is of such a figure that it may have been produced either by accident or through the whim of the workmen employed to hew out the stones. The double echo which Kircher assures us he heard in the grotto was not remarked by Schott, who was there in 1646, as he expressly says, in opposition to his brother jesuit, in his Magia Naturalis. In the accounts still remaining of Dionysius we find mention of an astonishing prison, which is well described by Cicero in his fifth oration against Verres: “You have all heard of,” says he, “and most of you know the prison (lautumias) of Syracuse. It is an immense and magnificent work, executed by kings and tyrants; the whole is sunk to a wonderful depth in the rock, and has been entirely cut out by the labour of many hands. No place so secured against an escape; no place so enclosed on all sides; no place so safe for confining prisoners can be either planned out or constructed.” But it cannot be proved, and according to D’Orville’s opinion it is improbable, that this grotto was the work of that tyrant, who, as Plutarch tells us in his Life of Dion, employed very different means to learn the intention of dangerous persons. “The common people attacked the tyrant’s friends, and seized those whom they called his emissaries (προσαγώγιδας), worthless men, detested by the gods. These went about the city, mixed with the citizens, and, prying into everything, gave an account to the tyrant of what they thought and what expressions they made use of.” It was merely for its strength, and the labour employed in building it, and not on account of its ingenious construction, that the ancients admired the prison of the tyrant. At present the upper end of the winding passage is closed up; and it is so narrow, that some years ago the captain of an English vessel found great difficulty to clamber up it. It cannot, however, be denied that this grotto may have been used for the service ascribed