every alternate sector polarized in an opposite manner. 7. When the crystal restores the vanished image, but allows it to vanish again during the revolution of the calcareous spar. Every body which possesses this kind of depolarization forms either a bright and a nebulous image, or a single image, the light of which is all polarized in the same manner. 4. On an Ebbing and Flowing Stream, discovered by boring in the Harbour of Bridlington. By John Storer, M.D.-In the year 1811 a boring was made in the harbour of Bridlington, in order to ascertain the thickness of the bed of clay which constitutes its bottom. The workmen having bored through 28 feet of very solid clay, and afterwards through 15 feet of a cretaceous flinty gravel of a very concrete texture, the auger was perceived to strike against the solid rock. As they were unable to make any impression upon this rock, the work was given up for that tide, without any appearance of water. But the pit gradually filled with fresh water; and when the tide rose within 49 or 50 inches of the mouth of the bore, this water overflowed, and continued to do so till the tide had ebbed so as to be 49 or 50 inches below the mouth of the bore. This pit was afterwards converted into a well, and it continues to overflow with the same regularity as at first. Mr. Milne, Collector of the Customs at Bridlington, has formed the following theory to account for this curious phenomenon. The bed of clay, he conceives, extends to Smithwick sand, which forms a bar across the opening of the bay, about four miles from the quay in a south-easterly direc tion. The rain water which flows below this clay cannot be discharged till it arrives at the ledge of rocks where the clay terminates. Its issue will meet with more or less resistance according to the depth of the sea water. Hence the reason why the well overflows every tide. There is a circumstance which Dr. Storer thinks militates against this hypothesis. After great rains, the column of spring water is elevated, and the discharge prolonged during each tide. He thinks the subject might be elucidated by a more perfect acquaintance with the peculiarities of the springs on this part of the coast which are called gipsies. 5. On the Effects of simple Pressure in producing that Species of Crystallization which forms two oppositely Polarized Images, and exhibits the complimentary Colours by Polarized Light. By Dr. Brewster. The author found that calf's-foot jelly and isinglass, when first gelatinized, did not possess the property of depolarizing light; but they gradually acquired it by keeping, and immediately by pressure between two plates of glass. 6. Experiments made with a view to ascertain the Principle on which the Action of the Heart depends, and the Relation which subsists between that Organ and the Nervous System. By A. P. Wilson Philip, Physician in Worcester.-From these experiments it appears that the brain or spinal mar be removed from the body, or destroy the action of the heart, provided art both of them, may hout impeding be kept up; that when stimuli (alcohol, opium, tobacco,) are applied to the brain or spinal marrow, the action of the heart is greatly increased; and that when the brain or spinal marrow is destroyed at once by crushing them, the action of the heart is destroyed or impeded. 7. Experiments to ascertain the Influence of the Spinal Marrow on the Action of the Heart in Fishes. By Mr. William Clift.From these experiments it appears that the heart of a carp continues to beat for several hours after the pericardium is laid open; that if the fish be left in the water, this action ceases much sooner than if the fish be allowed to remain quiet in the open air; that the spinal marrow may be destroyed, and the brain removed, without injuring the action of the heart; but that this action is somewhat injured by suddenly destroying the brain. 8. Some Experiments and Observations on the Colours used in Painting by the Ancients. By Sir Humphry Davy, LL.D. F.R. S. -The author, while in Italy, had an opportunity of examining some pigments found in the baths of Titus, and some dug up from Pompeii. He made experiments also upon the fresco paintings in the baths of Titus. The following are the facts which he ascertained: 1. The red colours employed in these paintings were red lead, vermilion, and iron ochre. 2. The yellows were yellow ochre, in some cases mixed with chalk, in others with red lead. The ancients likewise employed orpiment and massicot as yellow paints. 3. The blue was a pounded glass, composed of soda, silica, lime, and oxide of copper. Indigo was likewise employed by the ancients, and they employed cobalt to make blue glass. 4. The greens were compounds containing copper; sometimes the carbonate mixed with chalk, sometimes with the blue glass. In some cases they consisted of the green earth of Verona. Verdigris was likewise used by the ancients. 5. The purple colour found in the baths of Titus was either an animal or vegetable substance, perhaps the colouring matter of the murex combined with alumina. 6. The blacks were carbonaceous matter; the browns, ochres often containing manganese. 7. The whites were chalk or clay. White lead was known likewise to the ancient painters. 9. On the Laws which regulate the Polarization of Light by Reflection from Transparent Bodies. By Dr. Brewster.-This paper may be considered as a treatise on the subject. The author ascertained by experiment that the index of refraction is the tangent of the angle of polarization. From this law he shows how all the phenomena may be deduced, and the result of all the experiments determined beforehand. But from the great conciseness of the paper, and the mathematical dress in which it has been put, it is out of our power to convey to our readers an intelligent abridgment of it. II. A Treatise on the Economy of Fuel and Management of Heat, especially as it relates to Heating and Drying by means of Steam: in four Parts. 1. On the Effects of Heat, the Means of measuring it, the comparative Quantity of Heat produced by different Kinds of Fuel, Gas Light, &c. 2. On heating Mills, Dwelling-houses, Baths, and Public Buildings. 3. On drying and heating by Steam. 4. Miscellaneous Observations. With many useful Tables. Illustrated by Plates. With an Appendix: containing Observations on Chimney Fire-places, particularly those used in Ireland-on Stoves-on Gas Lights-on Lime-Kilns-on Furnaces and Chimneys used for rapid Distillation in the Distilleries of Scolland-on improved Boilers for evaporating Liquids. By Robertson Buchanan, Civil Engineer.-Glasgow, 1815. This ample title-page is sufficient to inform the reader what he may expect to find in this useful little work, which is of too miscellaneous a nature to admit of an analysis within any reasonable compass. The most valuable part of it consists in the details with which it furnishes us respecting the modes of warming buildings by steam employed by manufacturers in different parts of Great Britain. III. A Practical Treatise on Gas Light: exhibiting a summary Description of the Apparatus and Machinery best calculated for Illuminating Streets, Houses, and Manufactories, with Carbureted Hydrogen or Coal Gas: with Remarks on the Utility, Safety, and General Nature of this new Branch of Civil Economy. By Frederick Accum, Operative Chemist, Lecturer on Practical Chemistry, on Mineralogy, and on Chemistry applied to the Arts and Manufactures, Member of the Royal Irish Academy, Fellow of the Linnæan Society, Member of the Royal Academy of Sciences at Berlin, &c. &c.-London, 1815. This contains a perspicuous and popular view of the subject, and may be of considerable utility to those who, without being acquainted with chemistry, wish to have some general notion of the nature of gas lights. ARTICLE XII. Proceedings of Philosophical Societies. ROYAL INSTITUTE OF FRANCE. Account of the Labours of the Class of Mathematical and Physical Sciences of the Royal Institute of France during the Year 1814. (Continued from p. 149.) M. Auguste de St. Hilaire, several considerable botanical dissertations by whom we have formerly mentioned, has given us one this year on different families of plants, in which the placenta, that is to say, the part of the fruit to which the grains adhere, is simple, and placed in the middle of the fruit, like a column or an axis. When the summit of this column is free, the way by which the influence of the pollen is transmitted from the pistil to the seeds, appears to be very complicated, and to be by means of vessels which run along the fruit itself to penetrate the placenta at its base, and go to the seeds side by side of the nourishing vessels. Such, in fact, is the direction of these vessels in the amarantacea, according to M. de St. Hilaire. But this observer has remarked that in most plants of the category which he studies, and particularly in the primulaceae, the portulaceae, the caryophyllea, fecundation takes place in a more direct way. For this purpose there exists at first very fine vessels, proceeding from the base of the style to the summit of the placenta. These filaments are destroyed after fecundation, and then only the summit of the placenta becomes free. M. de St. Hilaire conceives also that there always exists a point or a pore different from the umbilicus, by which the fecundating vessels arrive at the grain, and to which M. Turpin, as we have mentioned in one of our preceding reports, has given the name of micropile. The part of M. de St. Hilaire's memoir which is purely botanical presents many detailed observations (unfortunately scarcely susceptible of analysis) on the particular characters of certain plants of the families that he examined, some of which, in his opinion, ought to serve as types for new genera, and others ought to pass into families different from those in which incomplete observations have hitherto placed them.. The pisang plantain, or fig-tree of Adam, is an herbaceous plant of the height of a tree, very remarkable for the enormous size of its leaves, and celebrated for the utility of its fruits, which furnishes to the inhabitants of the torrid zone one of the principal articles of their food. The cultivation of it has multiplied the varieties to such à degree, that there are probably as many sorts as we possess of apples or pears; and it is equally difficult to distinguish among them the primitive species. Accordingly botanists differ very much in their enumeration of the species, and in the characters which they assign to them. M. Desvaux, who has collected all that observers say of the dif ferent plantains, of the difference of their fruits and of their uses, thinks that there are 44 varieties in the common species, or musa paradisiaca of Linnæus; and three distinct species of this plant, namely, the musa sapientum, Lin. the musa occinea, pretty common at present in our green-houses, and the ensete, described by. Bruce in his Journey to the Sources of the Nile. The fig is a tree, the fruit of which has undergone still greater modifications by culture than the plantain. M. le Marquis de Suffren, who lives in Provence, a country anciently celebrated for the goodness of its figs, perceiving that the cultivators and proprietors are far from knowing all the good varieties, which are suit able to each soil and each exposure, and that they do not draw from that precious tree all the advantages which might be obtained, has undertaken to examine and describe with attention the different figs cultivated on the coasts of the Mediterranean, from Genoa to Perpignan. He has already collected coloured figures, and made an exact description, of 172 varieties; and his general_review is not yet terminated, as he has not exhausted the whole of Provence, and has not yet visited the coast of Languedoc. The part of this undertaking which has been communicated to the Class announces a work which will be very useful to our southern departments, especially if the author add the requisite details respecting the leaves and buds, and if he complete the characters by accurate comparisons of the different varieties with each other. M. Thiebaut de Berneaux, who proposes to give a French translation of the works of Theophrastus, and who, in order to know more accurately the plants of which that celebrated successor of Aristotle has spoken, has planned, and partly executed, journeys into the countries where these vegetables grow, has presented to the Class some of the results which he has already obtained, not only respecting the species indicated by Theophrastus, but likewise respecting those about which there is question in the other Greek and Latin authors. Thus the chara, which the soldiers of Cæsar discovered so hap pily under the walls of Dyrrachium, and the roots of which preserved them from famine, deserves to be ascertained. At present this name is given to a small aquatic plant, which certainly is not capable of nourishing any person: and respecting the chara of Cæsar, there are almost as many opinions as there are botanists who have attended to the subject. M. de Berneaux, after having examined and eliminated successively all these opinions, suggests one, of which Cluvius alone had some suspicion. He shows that the chara must be a species of cabbage, and thinks that it was the plant known at present by the name of crambe tartaria. This plant grows abundantly in the environs of Dyrrachium, and in all Hungary and Turkey. Its roots are very long and large, firin, and of a good taste, which are eaten both raw and boiled in all the countries of which we have spoken, and which are of great importance in times of scarcity. Several Latin authors distinguish by the name of ulva different marshy plants; but they distinguish particularly by that name one plant, which furnishes, they say, excellent food for sheep. As among aquatic plants there is scarcely any other than the festuca fluitans, which is sought after by sheep; and as this grass covers a great part of the marshes in Italy, M. de Berneaux conceives that it constitutes that peculiar species of ulva. He shows that all the passages in which it is mentioned apply very well to the festuca. He shows also that this is the grass which Theophrastus and the Greeks distinguished by the name of typha. The ancients boast much of the useful properties of the cytis |