Mr Guthrie modifies Amici's microscope, by removing altogether the plane speculum, and placing the object to be viewed in the axis of the tube. This arrangement is to the microscope what Sir W. Herschel's is to the reflecting telescope. In order that the object may be properly illuminated, the part of the tube next the mirror is wholly removed, and three pillars substituted for it, to one of which the stage for the object is attached, and regulated by an adjusting screw.

The object of the author in this paper is to state certain observations and experiments by which he considers it to be clearly established, that the periosteal membrane, covering the bones, has the power of secreting osseous substance and of forming new bony matter.

Duhamel, founding on a false analogy, which he supposed to exist between the periosteum and the bone on the one hand, and the bark and wood of trees on the other, was the first to lay down distinctly the theory that bony matter is formed by the investing membrane of the bones. The experiments and observations of Haller and others on the progress of ossification in young animals were believed, however, to militate against this idea, and tended rather to establish the doctrine, that new bony matter is formed by the pre-existing or old bone. Between these two theories, the opinions of physiologists and surgeons are still pretty equally divided.

These observations have reference chiefly to the intensity of the earth's magnetism, and were made for the most part with Hansteen's apparatus, in the possession of the society.

The first section of the paper refers to the method of making the observations, which is nearly that of Professor Hansteen.

The second refers to the corrections applied. These are—1. for the rate of the chronometer; 2. for reduction of the vibrations of the intensity needles to infinitely small arcs; 3. for the effect of temperature in diminishing the magnetism of the needles, which was determined for each by direct experiment; 4. for changes in the earth's magnetism; 5. for progressive changes in the needle's magnetism, which were considerable for one of the Hansteen needles, but for the other very small.

The introduction only of this communication was read. The abstract will be given after the paper is concluded.

A species of fixed oil, familiarly used in China for the same economical purposes for which olive oil is employed in Europe, has been ascertained by recent travellers in China to be produced in all probability by the tea-plant, or another species of the same natural family. The author assigns reasons for believing that it either is, or may be, obtained from the seeds of various species of the two genera Thea and Camellia. It has been hitherto almost unknown in Europe. It is when fresh quite free of smell, of a pale yellow tint, without any sediment when long kept. It resists a cold of 40° F., but at 39° becomes like an emulsion. Its density is 927. It is insoluble in alcohol, sparingly soluble in ether. It burns with a remarkably clear white flame.

The author has found a perfect resemblance to exist between the appearances presented by pyroxylic spirit (Bihydrate of Methyline of Dumas and Peligot) under voltaic agency, and those which he had previously observed in regard to alcohol; a coincidence which was to be expected, from the interesting analogy existing between these two liquids in other respects.

The pyroxylic spirit, after three distillations from quicklime, had a specific gravity of 801 at 62° F., and boiled in contact with mercury at 140° F., under a pressure of 29.5 inches. The leading facts observed were the following:—

Minute quantities of acid, alkaline, and saline bodies, when dissolved with rectified pyroxylic spirit, favoured the voltaic action, by increasing the conducting power of the liquid. When it held in solution of pure potash, and was submitted to the agency of thirty-six pairs of four-inch plates in a tube with parallel platinum foil poles, hydrogen was given off from the negative pole, while no gas proceeded from the positive pole. A ten thousandth part of potash had a marked effect in promoting this action.

The author obtained, in the early part of last September, at Brixham, in Devonshire, seven specimens of a species of Gurnard, which has been known for thirty years past to the fishermen there under the name of Finned Captains. This he ascertained to be the Trigla lucerna of Brunner. The species is known as an inhabitant of the Mediterranean, where it was first noticed by Rondeletius, but mistaken by him for the T. cuculus of Linnæus. Since then, Brunner noticed it at Marseilles, Risso at Nice, Leach at Malta, and Cuvier at Naples; but it had not been previously observed by any naturalist on the British coasts. The largest specimen obtained by the author is 10½ inches long. The back is light red, the pectoral fins dark blue, the sides marked by a silvery band from the gill-cover to the tail; the lateral line smooth, and formed by numerous semicircular plates, beautifully radiated at their free margin ; the scales thin, large, and entire; the second ray of the first dorsal fin very long, so as to reach, when folded down, beyond the sixth ray of the second dorsal fin. (See Plate.)

In this paper a new fluid composition is proposed for correcting chromatic aberration, free from the corrosive properties of those used by the author's father Dr Blair, the inventor of the fluid object-glass. The composition proposed is:—

The secondary spectrum formed by the nitrate, combined with crown-glass, is similar to that when flint and crown glass are combined. The combination of crown-glass with the muriate is the opposite. Hence, by properly combining these, Mr Blair states that the secondary spectrum may be wholly destroyed.

In this paper, the author confined his attention principally to those words of the original, which, in the received translation, are rendered “without form and void.” He considered that, in a philological point of view, the most correct translation is “vastness and emptiness,” or, in the adjective form, “immeasurable and imponderable.”

The bearing of the most recent philosophical discoveries, and of the opinions of natural philosophers and geologists, upon the interpretation of this passage, formed the next subject of inquiry. It was stated that there are three prevailing opinions in regard to the Mosaic account of creation, arising out of three different views with respect to the period when those strata were formed which contain organic remains.

Binny Crag in West Lothian is of compact greenstone, about half a mile in length, and from twenty to one hundred and forty feet in breadth. It extends south and north, and has a small ravine on its west side, above which the highest part of the crag rises about two hundred feet. Three phenomena connected with this crag are worthy of observation. 1. It has the character of a trap vein which has ruptured the strata in a fluid state. The dip of the sedimentary rocks on its west side is to west-south-west, on the east side to the east, and in both cases at a pretty high angle. We have here, therefore, evidence of the strata having been ruptured, and a fissure formed; and we have the trap, the rupturing agent, placed on the fissure, and occupying the anticlinal line, or axis of the upheaving movement. According to the received hypothesis respecting the origin of trap, we might expect this appearance to be common, and yet it is rather rare.

These experiments were made upon students in the University of Edinburgh, chiefly between the ages of 14 and 25, and, were intended to illustrate the general inquiry as to the law of physical development with age, but more particularly to afford data for instituting comparisons between different nations. For this purpose, throughout these experiments, natives of Scotland, England, and Ireland, were distinguished; and though the numbers belonging to the two latter countries were comparatively small, still the general coincidence of results, as to the three elements of weight, height, and strength, gives some confidence even in that part of the inquiry.

The author observes that, “in combining the surfaces of an achromatic eye-piece, a very limited question is resolved. The condition is, that pencils of light falling upon the first surface in directions parallel [approximately] to the axis of the instrument, emerge from the last surface in such a way, that the different rays into which each is decomposed may be parallel among themselves. On account of this restriction, achromatism can be obtained by the use of only one medium, and it is unnecessary to combine substances acting differently on the light of various colours.”

The author then proceeds to show that, since the only required conditions are that two refractions shall take place of a certain amount and at certain distances, these conditions may be fulfilled by two refracting surfaces, or by a single lens of a certain thickness.

This Paper contained the results of researches in hydrodynamics extending over a period of two years, and which the author is continuing to prosecute under the auspices of the British Association in conjunction with Mr Robison, the Secretary of this Society. The present paper contained the development of two new laws in hydrodynamics, which appeared of sufficient importance to form a paper by themselves.

These two laws are,

1. The Law of Emergence—as an Element of Resistance.

2. The Law of the Wave—as an Element of Resistance.

This is the first paper of a promised series on the subject here announced. In the present paper the author endeavours to shew, that in remote epochs the atmosphere was more extensive and heavier than it is now, that it contained a greater absolute quantity of oxygen, and that this quantity has gradually diminished up to our own era, and is probably still undergoing a sensible diminution. His views are founded partly on speculative considerations, of which it is not possible to give a sufficiently circumstantial abridgment, and partly on the evidence of various operations going on at or near the surface of the earth, the tendency of which must, on the whole, apparently be to diminish the quantity and proportion of the oxygen in the atmosphere. In addition to the ordinary and well known causes of deterioration, the author points out a new source of diminution to which his attention has been lately drawn. From experiments made upon the aeriform fluid discharged from the earth during an inundation, and obviously expelled by the water penetrating to a considerable depth, and displacing the gases contained in the soil, he found that this gaseous matter consists of 2.5 per cent, carbonic acid, 12.764 oxygen, and 84.736 nitrogen. Taking this observation in conjunction with many others previously made on the composition of the gaseous discharges in volcanic districts, and the gaseous contents of mineral waters, he infers that a process of oxidation is constantly going on at various depths below the earth's surface, the oxygen for which is in all probability derived by absorption of the atmospheric gases at the surface.

The author stated that, in July last, he obtained from the Frith of Forth a species of Bream, which he believes to be the Pagellus acarne of Cuvier. Length 13 inches; depth 4 inches; head one-third the length of the body not including the tail-fin. General form resembling that of the Sea Bream, but not so deep in proportion to its length. Scales large; 70 forming the lateral line, 6½ in an oblique row between it and the first ray of the dorsal-fin. Anterior-teeth small and numerous, disposed in many rows; outer row composed of 30 teeth, longer and more bent than those within; molars large, disposed in three rows in each jaw.

D 12–12, P 16, V8, A 3–11, C. 20. Body pale silvery red. Dorsal and caudal fins rose-red; ventral and anal fins paler. Between the eyes reddish-brown; in front of the eyes and on the lower half of the preoperculum, metallic grey; on the upper part of the base of each pectoral fin, a deep violet-coloured spot, very conspicuous even in the dried state.

This mineral, as described by the author about two years ago in the London and Edinburgh Philosophical Journal, presents a new and very interesting example of the principle known to crystallographers by the name of dimorphism; having the same chemical constitution as the well known Baryto Calcite of Brooke, but having a form belonging to an entirely different system of crystallization. In Dr Thomson's System of Mineralogy lately published, however, it is described as a mineral species before unknown, having a composition different from that of every known mineral, and is therefore distinguished by the name of the Bicalcareo carbonate of Baryta.