In deducing the mean of observations for June, the variation of the morning observation of the 18th is rejected, on account of its uncommon greatness. Between noon of the 1st June 1.927 inch, Rain fallen Between noon of the 1st July Evaporation during the same period.... .2.9 ARTICLE IX. ANALYSES OF BOOKS, Philosophical Transactions of the Royal Society of London, for the Year 1814, Part II. This part contains the following papers. I. On a new Principle of constructing his Majesty's Ships of War. By Robert Seppings, Esq, one of the Surveyors of his Majesty's Navy. This method, which appears to be the greatest improvement introduced into ship-building for many years, consists in substituting triangular or oblique beams for the parallel ribs which have hitherto constituted a ship's frame. This adds prodigiously to the stiffness and strength. The intervals between these beams are filled by solid pieces of wood driven in and calked and pitched, so that the ship would swim even if the external coating of planks were removed. This method renders the internal coating of planks unnecessary, and this adds considerably to the size of the hold. The decks are not loose as was the case in the old system; but systematically connected with the sides of the ship, so as materially to increase the strength of the whole. II. Remarks on the employment of oblique Riders, and on other Alterations in the Construction of Ships. Being the Substance of a Report presented to the Board of Admiralty, with additional Demonstrations and Illustrations. By Thomas Young, M.D. For. Sec. R. S.-In this paper Dr. Young considers in the first place the different forces which act upon a ship when sailing, and the effects apt to be produced by these forces. He then examines the different arrangements of Mr. Seppings, and shows that they are all improvements; though, if we understand him right, he seems to state that several of them are not new. III. Some further Observations on Atmospherical Refraction. By Stephen Groombridge, Esq.; F.R.S.-In a preceding volume of the Transactions Mr. Groombridge published a paper on this important subject, giving a formula for the mean refraction down to 80° from the zenith, deduced from his own observations. He has since continued his observations and determined the refraction as low down as 87°, the trees in Greenwich Park preventing him from observing stars any nearer the horison. He has made some alterations in his preceding formula. The paper concludes with a table of the mean refraction from the zenith to the horizon. IV. Propositions containing some Properties of Tangents to Circles; and of Trapeziums inscribed in Circles, and non-inscribed. Together with Propositions on the Elliptic Representations of Circles upon a Plane Surface by Perspective. By Richard Hey, LL. D. late Fellow of Sidney Sussex, and Magdalen Colleges in the University of Cambridge.-It is not in our power to give any intelligible account of this curious paper to our readers without the assistance of figures, and without introducing demonstrations not quite consistent with the nature of a review. We must therefore refer those who wish to study the subject to the paper itself. V. On the new Properties of Light exhibited in the Optical Phenomena of Mother-of-Pearl and other Bodies, to which the superficial Structure of that Substance can be communicated. By David Brewster, LL.D. F.R.S. Edin. and F.S.A. Edin.-The beautiful play of colours exhibited by mother-of-pearl, has been always ascribed to its laminated structure. Dr. Brewster, however, observed that the same property was communicated to wax, gum, tin, lead, &c., merely by pressing them against the surface of mother-of-pearl. Hence it is obvious, that the property is owing to the configuration of the surface. Dr Brewster found by means of the microscope, that the surface of mother-of-pearl was composed of waving lines, something like the skin at the point of an infant's finger. These lines could not be obliterated by grinding or polishing. They vary considerably in fineness in different specimens. Sometimes they may be seen with the naked eye, while at others more than 3000 may be reckoned within the space of an inch. To this configuration of the surface Dr. Brewster ascribes the property of mother-of-pearl to reflect various tints of splendid colours. Dr. Brewster found likewise, that when a ray of light falls obliquely upon mother-of-pearl, both the portion reflected and the portion transmitted are polarized, and both in the same manner. This is different from what happens either in crystallized or uncrystallized bodies. . VI. An improved Method of dividing Astronomical Circles and gra other Instruments. By Captain Henry Kater.-It is not possible to convey an adequate idea to the reader of the method of duating contrived by Captain Kater, without the assistance of figures. We must therefore refer those who wish to understand this important subject to the paper itself. VII. Results of some Experiments on the Properties impressed upon Light, by the Action of Glass raised to different Temperatures, and cooled under different Circumstances. By Dr. Brewster.-The author found that a ray of light passed through hot glass was depolarized; but when the glass cooled the original polarization was restored. Prince Rupert's drops exhibited the same phenomenon, together with the coloured rings, which characterise doubly refracting crystals. VIII. Considerations of various Points of Analysis. By John F. W. Herschel, Esq. F.R.S. The subjects treated of in this paper preclude the possibility of abridging it. IX. Observations on the Functions of the Brain. By Sir Everard Home, Bart. F. R.S.-The author conceives that it would greatly tend to promote our knowledge of the uses of the particular parts of the brain, if anatomical surgeons would collect all the observations which they have an opportunity of making in cases of injury of that organ. The present paper contains an arranged collection of his own observations in the course of his practise. 1. A certain degree of pressure is requisite to keep up the functions of the brain. A diminution of it produces faintness, an increase insensibility. The water in the ventricles may increase indefinitely without injuring the functions of the brain, if the skull expands in the same proportion. A curious example of this is detailed. 2. Concussion of the brain produces delirium and coma. 3. Sudden dilatation of the blood vessels of the cerebrum, in consequence of exposure to the sun, is sometimes accompanied by delirium, loss of speech and the power of swallowing. 4. Blood extravasated in the lateral and third ventricles was attended by repeated fits of vomiting and coma. In other parts of the brain it produced stupor, paralysis, idiotism. 5. The formation of pus is attended with delirium. 6. Depression and thickening of different portions of the skull was attended with heaviness, torpor, head-ache, &c. 7. Tumors in different parts of the brain produced violent head-aches, apoplexy, loss of sight, epileptic fits, &c. 8. Wounds in the anterior lobes of the brain produced no sensible effect. Loss of a portion of one of the hemispheres was attended with difficulty of swallowing for 24 hours, and slight delirium of short duration. 9. In a boy in whom the tuberculum annulare had become indurated, the effects were, that the boy had been an idiot from his birth, never walked, spoke, or understood what was said. 10. Pressure upon the medulla spinalis produces paralysis. X. Further Experiments and Observations on Iodine. By Sir H. Davy, LL.D. F.R.S. V.P.R.I.-This paper is divided into five sections. 1. On the triple compounds containing iodine and oxygen. When iodine is dissolved in potash or soda, two compounds are formed; one composed of oxygen, iodine, and potassium or sodium; the other of iodine and potassium or sodium. Our author calls the first oxiode of potassium, &c. the second iode of potassium, &c. When the alkali is saturated with iodine crystals are deposited. These are to be digested in alcohol of 8.6, or 9.2. The undissolved portion is the triple compound. Oxiode of potassium is almost tasteless, has no action on vegetable colours, is scarcely soluble in cold water; but more so in hot water. By heat it may be dissolved in sulphuric, nitric, and phosphoric acids. The saturated solutions congeal and form crystalline masses of an intensely acid taste. When strongly heated the triple compound is' decomposed at the temperature at which the acids are driven off, and oxygen and iodine exhales. Oxiode of potassium dissolves readily in phosphorous acid. When the solution is heated the acid is converted into the phosphoric, and iodine appears. When thrown into muriatic acid, an effervescence is perceived, the smell of chlorine becomes sensible, and the fluid, when evaporated, yields chlorionic acid. Similar appearances take place with the vegetable acids and the oxiode; all easily explained by the transfer of oxygen to the solvent. Sir H. Davy conceives oxiode of potassium to be composed of one atom iodine, one atom potassium, and six atoms oxygen; but his experiments scarcely seem sufficient to warrant any such conclusion. He formed likewise by a similar process, oxiodes of barytes, lime, and magnesia. His attempts to obtain a compound of oxygen and iodine were not attended with success. 2. On hydrionic acid and the compounds obtained by means of it. This acid is obtained pure by heating iode of potassium and hydro-phosphoric acid together. It is slowly decomposed by heat, and rapidly when heated along with oxygen gas. When condensed in water it is instantly decomposed by nitric acid and iodine precipitated. It rapidly absorbs oxygen from the air, and becomes yellow, and at last a deep tawny orange. It will probably answer well as a eudiometrical substance. It was decomposed by all the metals tried, except gold and platinum. With the alkalies and common earths it forms compounds very similar to those formed with the same bases by muriatic acid. 3. On other acid compounds of iodine. Iodine absorbs nearly one third of its weight of chlorine gas, and forms a very volatile compound, which acts upon mercury, and is dissolved by water. Sir H. Davy supposes that this compound is composed of an atom of iodine and an atom of chlorine. He calls it chlorionic acid. Its colour is yellow, and it readily dissolves iodine becoming deeper coloured. When agitated in chlorine gas it becomes colourless. In this state, when poured into alkaline or earthy solutions, oxiodes are precipitated. If it be coloured a quantity of iodine appears at the same time. When |