in one case being derived from the placenta, in the other from the mamma of the mother kangaroo. "From the foregoing facts certain conclusions may be drawn. "1. With regard to the placenta. "Since the organs of the fœtal bird are in the same condition as in the human fœtus, the nature of the blood supplied to them is probably the same. If so, the umbilical vein of the human foetus contains blood highly nutritious and arterial in character, and therefore the function of the placenta corresponds to that of the chorion membrane, yelk, and white combined; it is in fact the means of absorption, as the veins absorb the yelk and white, and the substitute of the lung in adult life. There is no need of lymphatic vessels in the placenta. "2. With regard to the liver. "That the function of this organ is to separate a highly nutritious substance from the blood of the portal vein; and this is true both of the liver of the foetal bird and of the human foetus. "3. That this albuminous substance is not in a condition to be directly absorbed from the umbilical vein, but is elaborated and separated for absorption by the lacteal vessels. "4. That there is reason to believe that this function of the liver continues to a great extent during adult life; for the portal vein in that state receives veins which correspond to the umbilical vein in the fact that they proceed from the source of nutrition. That the liver must be actively engaged after the introduction of food into the intestinal canal, and its secretion then more plentiful than at other times." II. "Completion of the Preliminary Survey of Spitzbergen, undertaken by the Swedish Government with the view of ascertaining the practicability of the Measurement of an Arc of the Meridian." In a letter addressed to Major-General SABINE by Captain C. SKOGMAN, of the Royal Swedish Navy: dated Stockholm, Nov. 21, 1864. Communicated by the President. Received December 15, 1864. "On the receipt of your letter of the 12th of November, I started immediately in quest of Professor Nordenskjöld, to obtain from him the materials for the fulfilment of your wishes in respect to the Spitzbergen Expedition. The Professor, with his usual obliging frankness, at once complied with my request, and communicated to me the Minutes from which I have compiled the subjoined brief Report of his proceedings. You must excuse the hasty manner in which the Report itself, as well as the accompanying map, has been put together, as time presses if my letter has to reach you before your Anniversary on the 30th. The map has no pretensions to exactness, but must be viewed merely in the light of a dia VOL. XIII, 2 T gram to show the extent and shape of the triangles, which may also have to undergo future minor modifications. "Report on the Swedish Expedition to Spitzbergen in 1864. "During the expedition of 1861 several attempts were made to penetrate into the Storfjord, or Wide Jaws Water; but from ice and calms (the Expedition not being provided with a steamer) they all proved ineffectual. As it was evident, however, that the firth in question is, beyond comparison, the best locality in the island for carrying on the measurement of an arc of the meridian, provided only that it is accessible to vessels, it was resolved that a fresh attempt should be made; and the Estates of the Kingdom having liberally granted the necessary means, another Expedi tion was fitted out, though on a smaller scale than that of 1861. Mr. Chydenius, who in 1861 had been particularly occupied in selecting and determining the stations for the Survey, unfortunately died in the beginning of 1864. His place has been supplied by Professor Nordenskjöld of the Academy of Sciences at Stockholm, and Mr. Dunér, Professor of Astronomy in the University of Lund, both having been in the Expedi tion of 1861. "A small vessel having been chartered at Tromsoe in Norway, they started in the first days of June, and made Bear Island on the 17th, having been detained by gales and adverse winds. Shortly afterwards they reached the opening of the Storfjord; and there appeared to be a good chance of getting in; but the ice soon packed, and, after several ineffectual attempts to force the vessel through, they had to bear up to the western side of Spitzbergen. On June 23rd they were off Bell Sound, but ice and calms prevented their getting in. On June the 25th they anchored at Safe Haven in Ice Sound. Here they remained shut in by the ice until July 16th, making the best use they could of their time by examining the greater part of the Sound, which was found to be considerably larger in extent than is laid down in the charts. Having got out, and returning to the southward, they were met by a heavy southerly gale, which obliged them to run for Bell Sound, where they were detained until July 27th, meanwhile completing the survey of the coasts of that Sound. Being again delayed by head-winds and calms, they did not reach South Cape until August the 7th, and on the 9th had succeeded in getting past the Thousand Islands to Whalers' Point, close to which is one of the southernmost stations within the firth* [marked v on the Map, from which, at a height of 1200 feet, the summits of the three stations, w, 7, and p, were seen against the sky]. On the 10th they reached Foul Point, on the opposite land [where a mountain, 1600 feet high (7), was ascended, from which the summits v, p, §, and o were seen projected against the sky, with the exception of o, which was backed by land]. On the 16th the third * The sentences within brackets are supplied from a letter of a still more recent date, from Dr. Otto Torell and Professor Dunér, written from Lund. station, p, was visited [and, from a height of 1100 feet, the summits v, t, ,, and were observed projected against the sky, and against other mountains]. On the 21st, after having ridden out a heavy gale, they succeeded in climbing Mount Walrus [marked #], a mountain 1100 feet high, surrounded by glaciers, and laid down as an island on the existing charts. [From this mountain the station marked λ in Mr. Chydenius's map (Royal Society Proceedings, vol. xii. Plate IV.) was seen.] "Proceeding in the boats they reached, on the 22nd, and ascended a mountain 2500 feet high, situated near the channel which joins the Storfjord with the southern opening of Hinlopen Straits. This was named White Mountain [and is marked on the Map]. From this summit they saw on a clear bright day the South Cape of North-east Land (u), Mount Löven about the middle of Hinlopen Straits on the west shore, and the station marked on the eastern shore. Having thus ascertained satisfactory points in the Storfjord, they proceeded again to the west coast of Spitzbergen, with the intention of pushing to the northward as far as possible, but had not proceeded far when they fell in with several boats with the crews of wrecked sealing vessels. Of course they were obliged to take these men on board; and being short of provisions for the increased number of hands, and the season drawing towards its close, they put back to Tromsoe. The sealing vessels had been wrecked on the east side of North-East Land, having got there by the north of the island. The men had afterwards made their way in the boats through Hinlopen Straits, having thus circumnavigated North-East Land-a feat said never to have been accomplished before. "The shores of the Storfjord are mountainous. The glens and valleys between the ridges are for the most part filled by glaciers, especially on the western shore. The mountains average from 1000 to 1500 feet in height, and belong in general to the Jura formation, which is here and there broken through by basaltic rocks (hyperite). In the Jura have been found skeletons, though not complete, of an Ichthyosaurus, closely resembling the species found in Arctic America by Sir Edward Belcher's Expedition. Mr. Malmgren, of the University of Helsingfors in Finland, accompanied the Expedition in the capacity of zoologist." III. "On the Sextactic Points of a Plane Curve." By A. CAYLEY, F.R.S., Sadlerian Professor of Mathematics, Cambridge. Received November 5, 1864. (Abstract.) It is, in my memoir "On the Conic of Five-pointic Contact at any Point of a Plane Curve" (Phil. Trans. vol. exlix. (1859) pp. 371-400), remarked that as in a plane curve there are certain singular points, viz. the points of inflexion, where three consecutive points lie in a line, so there are singular points where six consecutive points of the curve lie in a conic; and such a singular point is there termed a "sextactic point." The memoir in question (here cited as "former memoir ") contains the theory of the sextactic points of a cubic curve; but it is only recently that I have succeeded in establishing the theory for a curve of the order m. The result arrived at is that the number of sextactic points is =m(12m-27), the points in question being the intersections of the curve m with a curve of the order 12m—27, the equation of which is (12m2-54m+57) H Jac. (U, H, Qμ) +(m-2) (12m-27) H Jac. (U, H, QF) where U=0 is the equation of the given curve m, H is the Hessian or determinant formed with the second differential coefficients (a, b, c, f, g, h) of U, and, (A, B, C, F, G, H) being the inverse coefficients (A-be-f3, &c.), then Q=(A, B, C, F, G, HXdx, dy, dz)3 H, = ¥=(A, B, C, F, G, HXd, H, d, н, d, H)2; and Jac. denotes the Jacobian or functional determinant, viz. and Jac. (U, H, 2) would of course denote the like derivative of (U, H, &); *the subscripts (H, U) of denote restrictions in regard to the differentiation of this function, viz. treating as a function of U and H, Q=(A, B, C, F, G, Ha', b', c', 2f", 2g', 2h' ); if (a', b', c',ƒ', g', h') are the second differential coefficients of H, then we have viz. in d. we consider as exempt from differentiation (a', b', e', f, g, h) which depend upon H, and in dã Nʊ we consider as exempt from differentiation (A, B, C, F, G, H) which depend upon U. We have similarly dyQ=dy N+λy NJ, and d2 =d, N+d; and in like manner Jac. (U, H, )=Jac. (U, H, Qμ)+Jac. (U, H, Qμ), which explains the signification of the notations Jac. (U, H, Nμ), Jac. (U, H, NJ). The condition for a sextactic point is in the first instance obtained in a form involving the arbitrary coefficients (λ, μ, v); viz. we have an equation of the order 5 in (λ, μ, v) and of the order 12m-22 in the coordinates (x, y, e). But writing 9=x+y+vz, by successive transformations we throw out the factors 9, 9, 9, 9, thus arriving at a result independent of (A, μ, ); viz. this is the before-mentioned equation of the order 12m-27. The difficulty of the investigation consists in obtaining the transformations by means of which the equation in its original form is thus divested of these irrelevant factors. IV. "On a Method of Meteorological Registration of the Chemical Action of Total Daylight." By IIENRY E. ROSCOE, B.A., F.R.S. Received November 8, 1864. (Abstract.) The aim of the present communication is to describe a simple mode of measuring the chemical action of total daylight, adapted to the purpose of regular meteorological registration. This method is founded upon that described by Prof. Bunsen and the author in their last Memoir* on Photochemical Measurements, depending upon the law that equal products of the intensity of the acting light into the times of insolation correspond within very wide limits to equal shades of tints produced upon chloride-of-silver paper of uniform sensitiveness-light of the intensity 50, acting for the time 1, thus producing the same blackening effect as light of the intensity 1 acting for the time 50. For the purpose of exposing this paper to light for a known but very short length of time, a pendulum photometer was constructed; and by means of this instrument a strip of paper is so exposed that the different times of insolation for all points along the length of the strip can be calculated to within small fractions of a second, when the duration and amplitude of vibration of the pendulum are known. The strip of sensitive paper insolated during the oscillation of the pendulum exhibits throughout its length a regularly diminishing shade from dark to white; and by reference to a Table, the time needed to produce any one of these shades can be ascertained. The unit of photo-chemical action is assumed to be that intensity of light which produces in the unit of time (one second) a given but arbitrary degree of shade termed the standard tint. The reciprocals of the times during which the points on the strip have to be exposed in order to attain the standard tint, give the intensities of the acting light expressed in terms of the above unit. By means of this method a regular series of daily observations can be kept up without difficulty; the whole apparatus needed can be packed up into small space; the observations can be carried on without regard to wind or weather; and no less than forty-five separate determinations can be made upon 36 square centimetres of sensitive paper. Strips of the standard chloride-of-silver paper tinted in the pendulum photometer remain as the basis of the new mode of measurement. Two strips of this paper are exposed as usual in the pendulum photometer: one of these strips is fixed * Phil. Trans. 1863, p. 139. |