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Bidrag til rigtigere Opfattelse af Flyndernes Bygning. Svo vol.
Compte-Rendu Annuel adressé a S. Exc. M. de Reutern, Min. des Finances par le Directeur de l'Observatoire Physique Central .... pour l'année 1861 – 1863. 3 påmph. 4to. St. Peters
burg. 1862-1864. Ferdinand Müller.
Considérations sur la prévision des tempêtes et spécialement sur celles du 1 au 4 Décembre 1863. Par Ferdinand Müller, Assist. à l'Obs. Phys. Centr. (Suppl. aux Ann. pour 1861.) 4 pamph. St.
Bericht über eine Reise durch Schweden und Norwegen im Sommer 1863. 8vo pamph. Vienna.
Vorläufige Aufzählung der Arten der Gattungen Hydrobia Htm. und Amnicola Gld Hldm in der kaiserlichen und in Cuming's Sammlung. .. .. 8vo pamph. Vienna. 1863.
Ueber eine merkwürdige Verfarbung eines Gimpels. . . . . 8vo pamph. Vienna. 1863.
Beitrag zur Metamorphosengeschichte aus dem Jahre 1862. 4 Feb. 1862, und 11 Nov. 1863. 2 pamph. 8vo. Vienna. 1863.
Ueber gallenbildende Insekten in Australien. Briefliche Mittheilung von H. L. Schrader in Sidney. .... 8vo pamph. Vienna. 1863.
Bemerkungen über Strigops habroptilus, eingesendet aus Canterbury auf Neuseeland, von Dr. Julius Haast — Uebersetzt aus dem Englischen, von Georg Ritter von Frauenfeld. 8vo pamph. Vi
enna. 1863. Dr. F. P. Liharz ik.
The Law of Increase and the Structure of Man — Prospectus, with the fac-simile of Alexander de Humboldt's Letter to the Author,
and Three Tables. 4to pamph. Vienna. 1862. M. Hoek et A. C. Oudemans.
Sur les Contractions dans les Mélanges de Liquides. 4to pamph. The Hague. 1864. H. de Saussure.
Recherches sur les Fonctions du Système Nerveux dans les Animaux Articulés. Par M. Yersin, Prof. 8vo pamph. Lausanne.
Mémoire sur Quelques Faits relatifs à la Stridulation des Orthoptères et à leur distribution Géographique en Europe. Par M. Yer
sin, Prof. 8vo pamph. Lausanne. Giambattista Dattino.
Arringhe Officiose dell' Avocato Giambattista Dattino gia Assessore Demaniale della Provincia di Chieti Socio di diversi Accade
mie. Svo vol. Naples. 1863. Prof. Giovanni Capellini.
Studi Stratigrafici e Paleontologici sull' Infralias nelle Montagne dell Golfo della Spezia, con due Tavole. 4to pamph. Bologna. 1862.
Carta Geologica dei dintorni dell Golfo della Spezia e Val di Magra Inferiore. Bologna. 1863.
Five hundred and fifty-sixth Meeting.
The PRESIDENT in the chair.
The President called the attention of the Academy to the recent decease of Dr. Francis Wayland of Providence, of the Associate Fellows; also among the Foreign Honorary Members, of Sir John William Lubbock, Sir William Rowan Hamilton, the astronomer Encke, Admiral William H. Smyth, and Admiral Lois Isidore Duperrey.
Mr. John C. Lee was elected Treasurer of the Academy to fill the vacancy left by the declination of Mr. Bowditch, who was elected at the previous meeting.
Mr. Ferrel presented the following paper :
On an Annual Variation in the Daily Mean Level of the
Ocean, and its Cause.
In discussing a large number of tidal observations, made at Brest, one of the results obtained is an annual variation of the mean level of the ocean which cannot be explained by the hitherto recognized changes of mean level. The mean height obtained for each month of the year is given in the following table, in which each monthly mean
is the result of ahont 800 obsortations nf high water and as many of low water. The only (auzes which have been supposed to wrici the mean level are a small astronomical term depending upon the sun's declination, the variation of atmospheric pressure, and the winds. The effect of the astronomical term is equal to a cos 2 l, in which a is a function of the latitude of the port, and I is the sun's longitude. The effect of the variation of atmospheric pressure is equal to 13".568 (P-p), in which p is the observed barometric pressure of the atmosphere in meters, and P the annual mean pressure. The coefficient 13m.568 is assumed upon the hypothesis that the variation of the mean level of the ocean at any place is to the variation of the barometric column as the specific gravity of mercury is to that of water. M. Dausy obtained 15m.5 for this coefficient from 150 observations of the tides and of atmospheric pressure, made at Lorient, but Mr. Lubbock from observations at Liverpool obtained only 11.1 for that port. The theoretical value is perhaps more nearly correct than either of the other two. In the second numerical column of the following table is given the atmospheric pressure at Paris in millimetres for each month of the year, taken from Kaemtz's Meteorology, which is assumed to vary but little from the pressure at Brest, so that it may be used in computing the effect of the variation of pressure upon the mean level of the sea at that port. The following variations of mean level corrected for the astronomical term and variation of atmospheric pressure must be the effect of the winds, and other causes. The value of a in the astronomical term for the latitude of Brest is — .007. The corrections and the corrected monthly mean heigths of the ocean are also given in the following table.
In connection with these results are given in the following table those obtained by Dr. Bache from the discussion of the tides at Key West, Florida, and published in the Coast Survey Reports, and also in Silliman's Journal (Second Series, Vol. XVIII. p. 305). They have been reduced from English feet to meters for convenience of comparison with the preceding results. The second numerical column contains the variations of atmospheric pressure at Havana, which is used for computing the corrections at Key West due to that cause. The coefficient of the astronomical term for Key West is +.005. The corrections and the corrected results are also given in the following table:
For the convenience of comparison the following graphic representation of the results for the two ports is given, the first and third curves representing the annual variation of mean level at Brest and Key West respectively, uncorrected for the effects of the astronomical term and the variation of atmospheric pressure, and the second and fourth the corrected results. The curves are somewhat irregular, because the number of both tidal and barometric observations is not great enough to eliminate all the accidental and other irregularities; but the dotted curves, cutting off small irregularities, although somewhat arbitrary, must very nearly represent the true results.
With regard to the effect of the winds in changing the mean level of the sea, either at Brest or Key West, little is known, but it is evident from various researches at other ports, that they can have but little effect, except for very short periods during heavy gales, and therefore cannot cause much change in the monthly means, or the means of the different seasons. M. Dausy concluded from his researches that the mean level of the sea was not sensibly altered at Lorient by breezes
or fresh winds, but that it fell om.080 by violent winds from the north to northeast, and rose the same quantity by those from the southwest, the south, or the southeast. (Comptes Rendus de l'Académie des Sciences, Tom. III. p. 136.) We have, therefore, reason to suppose that the variations in the prevailing winds in the different seasons of the year, since their averages or resultants cannot amount to more than a very gentle wind, can have but a small effect upon the mean level at Brest. Moreover, the winds from the south and southwest, which tend to cause a rise in the mean level, prevail the most, and with the greatest force, during the winter and spring, and hence cannot cause the preceding corrected variation of mean level, which is at its minimum during that time. There must, therefore, be yet some other cause affecting the mean level of the sea at Brest.
With regard to the effect of the winds on the mean level of the sea at Key West, Dr. Bache remarks, that “winds tending to elevate the water in the harbor prevail for six months, from March to August