Dr. Patterson read a paper by Professor Charles Bonnycastle, of the University of Virginia, containing "Notes of Experiments, made August 22d to 25th, 1838, with the view of determining the Depth of the Sea by the Echo." This paper, which was not offered for publication in the Society's Transactions, states that the generally received notions in regard to the intensity of sound in water, and the distance to which it is conveyed, had suggested to Mr. Bonnycastle, some years ago, the idea that an audible echo might be returned from the bottom of the sea, and the depth be thus ascertained from the known velocity of sound in water. The probability of this view was deemed at least sufficient to justify an experiment; and accordingly the Navy Commissioners authorized the construction of the necessary apparatus, and Captain Gedney, of the U. S. Brig Washington, attached to the coast survey, volunteered his services and the use of his vessel, and authority to this effect was liberally granted by the Secretary of the Treasury, Mr. Woodbury. The apparatus, which is fully described in Mr. Bonnycastle's paper, consisted, first, of a petard or chamber of cast iron, 24 inches in diameter and 54 inches long, with suitable arrangements for firing gunpowder in it under water; secondly, of a tin tube, 8 feet long and 14 inches in diameter, terminated at one end by a conical trumpetmouth, of which the diameter of the base was 20 inches, and the height of the axis 10 inches; thirdly, of a very sensible instrument for measuring small intervals of time, made by J. Montandon of Washington, and which was capable of indicating the sixtieth part of a second. Besides these, an apparatus for hearing was roughly made on board the vessel, in imitation of that used by Colladon in the Lake of Geneva, and consisted of a stove-pipe, 41⁄2 inches in diameter, closed at one end, and capable of being plunged four feet in the water. The ship's bell was also unhung, and an arrangement made for ringing it under water. On the 22d of August, the brig left New York, and in the evening the experiments were commenced. In these, Mr. Bonnycastle was assisted by the commander and officers of the vessel, and by Dr. Robert M. Patterson, who had been invited to make one of the party. In the first experiments, the bell was plunged about a fathom under water and kept ringing, while the operation of the two hearing instruments was tested at the distance of about a quarter of a mile. Both instruments performed less perfectly than was expected; the noise of the waves greatly interfering, in both, with the powers of hearing. In the trumpet-shaped apparatus, the ringing of the metal, from the blow of the waves, was partly guarded against by a wooden casing; but, as it was open at both ends, the oscillation of the water in the tube was found to be a still greater inconvenience, so that the sound of the bell was better heard with the cylindrical tube. At the distance of a quarter of a mile this sound was a sharp tap, about the loudness of that occasioned by striking the back of a penknife against an iron wire: at the distance of a mile the sound was no longer audible. In the second experiments, the mouth of the cone, in the trumpet apparatus, was closed with a plate of thick tin, and both instruments were protected by a parcelling of old canvas and rope-yarn, at the part in contact with the surface of the water. In these experiments the cone was placed at right angles to the stem, and the mouth directed toward the sound. The distances were measured by the interval elapsed between the observed flash and report of a pistol. At the distance of 1400 feet, the conical instrument was found considerably superior to the cylindrical, and at greater distances the superiority became so decided, that the latter was abandoned in all subsequent experiments. At the distance of 5270 feet, the bell was heard with such distinctness as left no doubt that it could have been heard half a mile further. The sounds are stated in the paper to have been less intense than those in air, and seemed to be conveyed to less distances. The character of the sound was also wholly changed, and, from other experiments, it appeared that the blow of a watchmaker's hammer against a small bar of iron gave the same sharp tick as a heavy blow against the large ship's bell. It is well known that Franklin heard the sound of two stones struck together under water at half a mile distance; yet two of the boat's crew, who plunged their heads below the water, when at a somewhat less distance from the bell, were unable to hear its sound. On the 24th of August, the vessel having proceeded to the Gulf Stream, experiments were made with the view for which the voyage was undertaken; that is, to ascertain whether an echo would be returned, through water, from the bottom of the sea. Some difficulties were at first presented in exploding the gun under water, but these were at length overcome. The hearing-tube was ballasted so as to sink vertically in the water. The observers then went, with this in strument, to a distance of about 150 yards from the vessel, and the petard was lowered over the stern, about three fathoms under water, and fired. The sound of the explosion, as heard by Mr. Bonnycastle, was two sharp distinct taps, at an interval of about one-third of a second. Two sounds, with the same interval, were also clearly heard on board the brig; but the character of the sounds was different, and each was accompanied by a slight shock. Supposing the second sound to be the echo of the first from the bottom of the sea, the depth should have been about 160 fathoms. To ascertain the real depth, the sounding was made by the ordinary method, but with a lead of 75 pounds weight, and bottom was distinctly felt at 550 fathoms, or five furlongs. The second sound could not, therefore, have been the echo of the first; and this was proved, on the following day, by repeating the experiment in four fathom water, when the double sound was heard as before, and with the same interval. The conclusion from these experiments is, either that an echo cannot be heard from the bottom of the sea, or that some more effectual means of producing it must be employed. Dr. Hare suggested the expediency of employing the Galvanic fluid to fire gunpowder below the surface of water, in experiments similar to those of Professor Bonnycastle. The President laid on the table for the inspection of the members, an English and Japanese, and Japanese and English Vocabulary, by the Rev. W. H. Medhurst, late of Batavia, now in London, and a "Translation of a comparative Vocabulary of the Chinese, Corean, and Japanese Languages, to which are added the thousand Characters classic, in Chinese and Corean; the whole accompanied by copious Indexes of all the Chinese and English Words occurring in the Work," by the same author, under the name of Philo-Sinensis. These two books, the President said, throw considerable light on the various graphic systems of the Indo-Chinese nations; they had been communicated to him by our associate, Mr. Pickering, of Boston, to whom they must be returned: he, therefore, recommended to the society to take measures to procure them for the library. The recommendation of the President was then adopted, and the books referred to, ordered by the society. Dr. Hare laid before the society a specimen of platinum, weighing between twenty-two and twenty-three ounces, being part of a mass of twenty-five ounces, fused by him in May last, by means of his compound blowpipe. Dr. Hare also mentioned that he had observed, during a recent tornado at Somerset, Mass. various circumstances, which he detailed, all leading to the conclusion that a hiatus or place of rest exists at the centre of motion of the tornado. Stated Meeting, October 5. Present, twenty-nine members. MR. DU PONCEAU, President, in the Chair. The following donations were received: FOR THE LIBRARY. Inquisitionum in Officio Rotulorum Cancellariæ Hiberniæ asserva- Rotulorum Patentium et Clausorum Cancellariæ Hiberniæ Calenda- Proceedings and Ordinances of the Privy Council of England. Lon don. Vol. V., 1835; Vol. VI. & VII., 1837.-From the same. Excerpta è Rotulis Finium in Turri Londinensi asservatis, Henrico Tertio Rege. Vol. II. London, 1836.-From the same. The Ancient Kalendars and Inventories of his Majesty's Exchequer. Three Vols. London, 1836.-From the same. Documents and Records illustrating the History of Scotland. Vol. I. London, 1837.—From the same. Rotuli Chartarum in Turri Londinensi asservati. Vol. I. Part. I. London, 1837.-From the same. General Report to the King in Council from the Honourable Board of Commissioners on the Public Records. London, 1837.From the same. Registrum vulgariter nuncupatum "The Record of Caernarvon;” è Codice Msto. Harleiano 696. descriptum. London, 1838.—From the same. The American Almanac and Repository of Useful Knowledge, for the year 1839. Boston, 1838.-From Mr. J. E. Worcester. Collections of the Massachusetts Historical Society. Vol. VII. of the third Series. Boston, 1838.-From the Society. History of the Reign of Ferdinand and Isabella, the Catholic. By William H. Prescott. Three Vols. Third Edition. Boston, 1838.-From the Author. Human Physiology; illustrated by Engravings. By Robley Dunglison, M. D. Two Vols. Third Edition. Philadelphia, 1838.From the Author. The Magazine of Natural History. New Series. Conducted by Edward Charlesworth, F. G. S. &c. Vol. II. Nos. 19 & 20, for July and August. London, 1838.-From the Conductor. The Transactions of the Linnean Society of London.. Vol. XVIII. Part the First. London, 1838.-From the Society. New Testament in the Chippewa Language. Albany, 1833. From the Hon. William C. Frazer. North American Herpetology; or, a Description of the Reptiles inhabiting the United States. By John Edwards Holbrook, M. D. Vol. II. Philadelphia, 1838.-From the Author. Proceedings of the Royal Irish Academy, for the year 1837-8. Part II. Dublin, 1838.-From the Academy. Note on the Solar Eclipse of May, 15, 1836. By Sears C. Walker. (From the Journal of the Franklin Institute.) Philadelphia, 1836.— From the Author. Note sur le Magnétisme Terrestre, suivie des Résultats des Observations Horaires, faites à l'Equinoxe du Printemps de 1838, par A. Quetelet. Brussels, 1838.-From the Author. Note sur le Magnétisme Terrestre, par A. Quetelet. Suivie des Résultats des Observations Horaires, faites a l'E'poque du dernier Solstice d'E'té, en 1838. Brussels, 1838.-From the Author. A Collection of Interesting French Pamphlets.—From D. B. Warden, Esq. Catalogue of the Hungarian Academy of Sciences, with a Calendar prefixed. (In Hungarian.) Buda, 1838.-From Mr. Charles Nagy. FOR THE CABINET. Three hundred copper coins, medals, and tokens, and other articles of interest. From Mr. James Linah, of Charleston, S. C. The Committee on Mr. Nulty's paper, read at the last meeting, recommended that it be printed in the Society's Transactions; and its publication was ordered accordingly. |