the circuit of the circle ppr, that is, the motion of the superficies contained between the circle ppr and the spheroid, in the direction îp, will be equal to the circumference of this circle drawn into TK2X PM2 TK X HM2 u X ABX d AM: TM :: TK: BK, and TH: HMTP: TK, by writing d for the circumference of the circle BDd, that motion will be = X (TK2 × PM + 2BK' X TM2 × PM2). Then the sum of these motions in the whole circuit of the globe collected, that is, the motion of the whole matter incumbent on the globe BDd, ux AB X d' 3TP2-BK will be = When the planet is in the plane of the TP2 X 32 16 equator, make BK = 0, and then the aforesaid motion is = But the motion of the globe QPR about the same axis, it is easily demonstrated, is * x TP X d1, therefore the motion of the whole earth is u x TP x d2 + ux 3AB X de 32 1 X AB X d 32 3TP2 BK* 16 , which, since it must remain always the same, making v denote the velocity in the superficies of the terrestrial equator when the planet is in the plane of the equator, it will then be % × TP x d' ux 3AB X da u x TP x d' 16 = + 32 AB X BK 16 ; hence, writing 1 for TP since it is the radius to the sine BK of the angle BтK, it will be vu: TP + ARAB X BK': TP + AB; and hence, because the altitude AB is extremely small in respect of the semidiameter TP, u — v :v :: AB × BK2: 2TP, X and uvv x But for v it is evident may be written the mean angular velocity of the earth, because differing from it by a very small quantity and drawn into the small quantity 2TP, and because the times of the earth's revolutions about its centre are reciprocally as the angular motions u, v, then the difference of the earth's revolutions between when the planet is in the equator and when distant from it by the angle BTK, is = 23h 56m × Because then the horary acceleration is to the mean horary motion of the earth about its centre, as AB × BK2 is to 2TP, or (because the sine p of the inclination of the ecliptic to the equator is to radius 1, as the sine BK is to the sine of the planet's distance from the equinox, which sine call ), as AB x p2 x k2 to 2TP; therefore the horary acceleration of the earth's rotation increases in the duplicate ratio of the sine of the planet's distance from the equinoctial point; and the sum of all those accelerations, while the planet passes from the equinox to the solstice, is to the sum of as many mean horary motions, that is, the total acceleration generated in that time, is to that time, as the sum of all the quantities AB × p2 x k2 in a quadrant of the circle, is to the sum of as many 2TP; that is, because the sum of all the k2 in a quadrant of the circle is half the sum of as many squares of the radius, as AB x p2 to 4TP. Therefore, if p denote the 4th part of the planet's periodic time about the earth, the total acceleration of the earth's motion about its axis, generated in the passage of the planet from the equinox to the solstice, will be = ABX PXP2; and the retardation will be the same in the 4TP planet's transit from the solstice to the equinox. Hence naturally arises this theorem: "The square of the diameter is to the square of the sine of ecliptic's obliquity, as the 4th part of the periodic time of the sun or moon, is to another time; then the earth's semidiameter is to the difference of the semiaxis, as the time just found, is to the acceleration sought. The rise AB of the water due to the sun's force is about 2 feet, the earth's mean semidiameter TP being 19615800; hence the theorem produces, for the earth's acceleration turning about its centre, made while the sun passes from the equinox to the solstice, the quantity 1" 55"" in parts of time. And if by the moon's force the waters rise to the height of 8 feet, the acceleration of the earth's rotation hence arising, while the moon moves from the equator to her greatest declination, will be 34""". And the sum of these accelerations, which obtains when these two planets occupy the solstitial points, since it exceeds not 24′′ of time, or 37"" of a degree, will hardly be sensible. Q. E. I. CXI. Observations on the History of the Norfolk Boy. By J. Wall, M.D. p. 836. Dr. W. attributes the evacuation of worms in this boy's case to the oil in the mixture of paint which he swallowed; and mentions that he had afterwards prescribed oil as a vermifuge, with good success. CXII. On the Corona Solis Marina Americana;* The American Sea-Sun-Crown. From the French of J. A. Peyssonel, M. D., F. R. S. p. 843. CXIII. On several Rare Species of Barnacles. By J. Ellis, Esq. F. R. S. p. 845. Some rare and extraordinary new species of barnacles, lately received from abroad, were so different from any of the common species, that Mr. E. was resolved to inquire into the nature of an animal, which, like a Proteus, appears in so many different shapes or coverings in different parts of the world. For this end he consulted that excellent collection in the British Museum, and some others in the cabinets of his friends. This marine animal is called by writers on natural history, balanus, and concha anatifera: but Linneus calls the internal active part, or fish, the animal triton, and the covering or testaceous habitation lepas, which he says is a multivalved shell, composed of unequal valves. The animal triton he describes, as having an oblong body, a mouth with a tongue in it, twisted *This is some species of actinia, but for want of a figure, it is hardly possible to tell what particular species is intended; neither is the description clear, so that it was thought not worth reprinting. about in a spiral manner; 16 tentacula or claws; 6 of the hinder ones on each side cheliferous. This account differing from that given by the ingenious Mr. Needham, in his Microscopical Essays, Mr. E. gives the character of this aniinal, as it appeared from many observations made on it, while alive in salt water; and these he compared not only with many dried specimens of other varieties, but likewise with some that were preserved in spirits; and he found that the parts of the animal agree in all the species. The experiments that he made, were on the common English barnacle, viewed by a microscope, which is very frequently met with, in the winter, on oysters and other shell-fish. This animal has 24 claws, or cirrhi (fig. a, pl. 11) which are disposed in the following manner: the 12 longest stand erect, rising from the back part of the animal; they are all joined in pairs near the bottom, and inserted in one common base. These appear like so many yellow curled feathers: they are clear, horny, and articulated. Every joint is furnished with 2 rows of hairs on the concave side. The animal, in order to catch its prey, is continually extending and contracting these arched hairy claws,, which serve it for a net. The 12 smallest claws are placed next to these, 6 on each side: these are divided into pairs; that is, 2 claws to one stem, like the chelæ or claws of the crab. These are more pliable, and fuller of hairs, than the others, and seem to do the office of hands for the animal. The whole number of claws lessen in size gradually each way, from the tallest in the back, to the last but one of each side in the front; which last 2 are of the middle size. The proboscis or trunk rises from the middle of the base of the larger claws, and is longer than any of them: this the animal moves about in any direction with great agility: it is of a tubular figure, transparent, composed of rings lessening gradually to the extremity, where it is surrounded with a circle of small bristles, which likewise are moveable at the will of the animal. These, with other small hairs on the trunk, disappear when it dies. Along the inside of this transparent proboscis the spiral dark-coloured tongue appears very plain : this the animal contracts and extends at pleasure. The mouth appears like that of a contracted purse, and is placed in front, between the fore claws. In the folds of this membranous substance are 6 or 8 horny laminæ or teeth standing erect, each having a tendon proper to direct its motion. Some of these teeth are serrated, others have tufts of sharp hairs instead of indentations on the convex side, that point down into the mouth; so that no animalcule that becomes their prey can escape back. Under the mouth lie the stomach, intestines, and the tendons by which they adhere to the shell. This then is the general character of the animal of the whole genus, whether with stems or without. Mr. E. next gives a short description of the several kinds he had met with, dividing them into 2 kinds; those that have stems, and those that adhere by their shelly bases. The first and most remarkable of those that have stems, is the barnacle: Fig. 1. This differs from the lepas of Linneus in not having a testaceous, only a cartilaginous or fleshy covering. On the top of it are 2 erect tubular figures like ears: these have a communication with the internal parts of the animal (fig. 1. b). These inner parts agree with the general character already given. The stem, which is here dissected, was full of a soft spongy yellow substance, which appeared, when magnified, to consist of regular oval figures, connected together by many small. fibres, and no doubt are the spawn of the animal. This extraordinary animal (of which there were 7 together) was found sticking to the whale barnacle (See fig. 1 and 7) by Mr. Smith of Stavenger in Norway, who cut both kinds together off a whale's lip, that was thrown upon that coast last year, 1757, and immediately immersed them in spirits of wine; by which means Mr. E. was able more exactly to describe them. Mr. E. called this animal the naked fleshy barnacle with ears; but it appears to claim, he thinks, the name of triton rather than lepas, according to Linneus, as having no shelly habitation. Fig. 2 is the next animal of this class: this is not yet described. Mr. E. found several of them. sticking to the warted Norway sea fan, sent here by Dr. Pontoppidan, the bishop of North Bergen : from its appearance, Mr. E. called it the Norway sea fan penknife. The stem of this is covered with little testaceous scales. The upper part of the animal is inclosed in 13 distinct shells, 6 on each side, besides the hinge-shell at the back, which is common to both sides these are connected together by a membrane that lines the whole inside. One of these is magnified a little at fig. 2, a, the better to express the figure and situation of each shell. Fig. 3 is taken from D'Argentville's Lithologie, pl. 30, fig. H, who says it is found in the British channel sticking to sea-plants; and that these shells consist of 5 pieces. This, from its appearance, Mr. E. called the British channel penknife, to distinguish it from the other. Fig. 4 is a species of barnacle called poussepieds by the French, and described by Rondeletius as commonly found adhering to rocks on the coast of Brittany. He says the people there boil and eat the stem, which is first of a mouse colour, and afterwards becomes red like our prawns. There are many heads, that rise out of one stem, each consisting of 2 shells, in which are the same parts of the animal as in the other species. This Mr. E. called the cornucopia barnacle. Some of the shells of this barnacle were drawn from a specimen in the British Museum. This lepas is the mitella of Linn. Fig. 5 and 6 are the barnacles called concha anatiferæ : these are the sorts so well known to sailors, aud formerly supposed to produce a large species of duck called a barnacle. These consist of 5 shells. The tube, that supports one of these kinds, branches out like some species of corallines, bearing a shelled animal at the end of each branch. They are generally found adhering to pieces of wood in the sea, and most ships have some of them sticking to their bottoms. Those of the southern and warmer climates are generally of a larger kind than those of the colder and more northern. The next division of these animals is, those that adhere by the base of their shells, having no stems. Here he observes, that the bottoms of the several species of this division conform in shape to the substances they adhere to, or grasp them in such a peculiar manner, as to render their situation secure from the violence of the element they live in. Another provision of nature for the security of these animals, are the 4 opercula, which, on their retreating into the great shell, they can draw to so close after them, as to secure themselves from outward danger. Fig. 7, represents the whale barnacle, called pediculus ceti, just as it was cut off the whale's lip, with the 7 naked barnacles with ears, already described. Fig. 7, a, is the bottom of the shell. This has the appearance of the gills of a mushroom. All the spaces between these lamina were filled with the blubber of the whale: by this means they adhere to the gristly skin of the fish. The narrow cavities between the branched lamina are the places where the liganients or tendons, that move the opercula, are inserted. Fig. 8, is the cup barnacle, taken off an East India ship from Sumatra. The testaceous flat bot tom of this was marked with the scams and lines of the sheathing, and with the rust of the nails. In one of these shells the animal is represented protruding his claws through the opercula. Fig. 9, is called the bell-shaped barnacle. This was taken off the bottom of a ship from Jamaica, and had its flat testaceous base marked as the former. Fig. 10, represents part of a most elegant specimen in the curious collection of Dr. John Fothergill. It is called the tulip barnacle, and very properly, as well from the shape of its shell as the beautiful stripes of red mixed with white. It adheres to a piece of the true red coral, and was fished up near Leghorn. It is not improbable, but that these groups of barnacles, growing at the same time with the animals that formed the red coral, may have received an addition to their fine red colour from the coral. Fig. 11, is a group of barnacles of a conical form, composed of purplish tubes like small quills. Fig. 11, a, represents one of the same, with a view of its base, from the collection of Mr. Peter Collinson, F.R.S. This was brought from the East Indies. The insides of these shells have the appearance of the spongy parts of bones. Fig. 12, is called the tortoise-wart barnacle, being often found upon that animal. This shell is of a plano-convex shape, and looks like polished ivory. The divisions between the valves represent a star with 6 points. If these shells are put into soap-lees, they will in a few hours separate into 6 pieces or valves, each shelly valve having 2 ears, like the scallop-shell: so that this species has its valves connected by membranes, instead of testaceous sutures, as most of the others have. Fig. 12, a, represents the under part of the same shell. Fig. 13, is marked with 6 rays like a star, as the former: but is much deeper in proportion to its diameter. Several of this kind were found sticking to a crab, that was lately brought from the island of Nevis; whence Mr. E. called it the American crab's-wart. Fig. 14, is called the side-mouth barnacle. This was found on the southern coast of Africa, near the Cape of Good Hope, where it adheres to a particular species of striated purple muscle. Fig. 14, a, represents 2 of the opercula of this barnacle remarkably horned. The shell of this is very thin; but its obliquity may probably be owing to its situation. Fig. 15. This egg-shaped barnacle with a small mouth is found in clusters sticking to the buccinum tribe of shells in the West Indies. Fig. 16, is the Cornish barnacle, shaped like a cone, and with a small mouth. This is described and figured by the Rev. Wm. Borlase, . R. s. in his Natural History of Cornwall. Fig. 17, is the common English barnacle, found in such plenty on all rocks and shells round this island. From the animal of this, examined in the microscope, Mr. E. took the character of the fish of the barnacle genus. Fig. 18, Mr. E. called the limpet-shaped barnacle, from its likeness to some species of that shell. It was brought from Greenland, and with several more was found sticking to a very large species of muscle. Fig. 19, a. This sea-fan, with the barnacles inclosed in it, was brought from Gibraltar. Mr. E. called it the slipper barnacle from its shape. See fig. 19. These shell-fish adhere, while they are young, to the slender branches, which are produced by the animals that compose this species of seafan; and as the next succession of young animals of this sea-fan creep up its sides, to increase the bulk and extension of these first-formed ramifications, they inclose the shells all round, leaving only their mouths or apertures open, for the barnacles to procure their food. But it frequently happens that the animals of the sea-fans destroy these barnacles, by overrunning and involving them in the very centre of their stems. These small barnacles, interspersed here and there on the branches, have |
