1. On the 2d September 1839, M. Arago communicated to the Academy of Sciences of Paris a letter by M. Melloni, containing some very interesting experiments on the transmission of Radiant Heat. M. Melloni finds that rock-salt (which is well known to transmit rays of heat from all sources yet tried with equal facility) acquires, by being smoked, the power of transmitting most easily heat of low temperature, or that kind of heat which is stopped in greatest proportion by glass, alum, and (according to M. Melloni) every other substance.

In 1836, I communicated to this Society the results of an extensive series of observations on Terrestrial Magnetic Intensity, made with the Hansteen Apparatus, which is the property of the Society. Some results with a small Dipping Needle, belonging to myself, were also given, but without great confidence in their accuracy.

I held then, however, the opinion which I still do, and to which the remarkable geometrical researches of Professor Gauss of Göttingen on Terrestrial Magnetism have given additional weight, that the element of horizontal intensity ought to be determined, and its laws of variation, in the first place, ascertained, independent of any other. Even should the deduction of total intensity be the sole ultimate object, I hold that an observer with only portable, and consequently imperfect instruments at his command, would do well to separate completely his investigations as to horizontal intensity from those upon dip, and then, by the skilful grouping of each set, having obtained a law of variation of each element according to the co-ordinates of Latitude and Longitude, the two partial results may be combined into the general one of total intensity , whilst either series may be used to check future observations, or be combined with any single future series in which one of the elements should be better determined.

The present Memoir is, to a certain extent, a continuation of one which the author presented to the Society in December 1838, and which has since been published in the thirteenth volume of the Transactions. Other motives, however, than the desire of completing the subject, have influenced him in producing the following analysis. A very important point in the hypothetical conditions which Fresnel assumed to hold with respect to polarized light, has, of late, been warmly combated in various quarters. Fresnel supposed that light polarized in a given plane consists of vibrations of such a nature that the motion is perpendicular to that plane. Neumann and other writers contend that the very opposite is the fact. We hope to be able to offer evidence of some little weight in favour of the former view; at the same time we do not pretend to shew the actual impossibility of the truth of the latter.

It has been justly observed that the great discovery of the appropriation of the different portions of the Nervous System to the exercise of different functions, would never have been clearly established, but for the fortunate circumstance that, in certain parts of the body, especially on the face, the nerves of sense and of voluntary motion are distinct throughout their whole course. And this consideration may instruct us that, when we have an organ supplied with a variety of nerves, known to be of perfectly different endowments, the study of the peculiarities of these nerves may give us an insight into the purpose or use of some of those pieces of structure in all parts of the Nervous System, in which we must still admit that we see much contrivance, without understanding its intention.

It is well known to those who have paid attention to the progress of Fossil Ichthyology that, until the publication of M. Agassiz, the distinctive characters of the orders, genera, and species of Fossil Fishes were but imperfectly understood. Vague analogies were relied on to connect them with the types of living genera, and the looseness of the received specific characters rendered it difficult for the geologist to determine whether the specimens he collected were previously recognised, or still nondescript. It is obvious that useful characters of fossil species are chiefly to be obtained from those portions of their structure least subject to alteration from decay; and as the exterior scaly envelopes of the primeval fishes are usually the portions best preserved and most easily recognised in their rocky sepulchres, M. Agassiz was naturally led to study these with minute attention. This acute observer speedily discovered that, in the form and connections of the scales, he had a general character which would enable him to connect into very natural groups, species differing from each other in size and form. On this basis he has established his four Orders of Fossil Fishes—the Ganoidei, the Placoidei, the Ctenoidei, and the Cyclodei—divisions named from the appearance of the scales.

Musket-Bullets are occasionally found inclosed in ivory, and every anatomical museum contains specimens of this kind. Why bullets should be so frequently met with in this situation, it is not easy to say; the head of the animal appears to be generally aimed at, and foreign bodies when they enter the tusks, instead of being removed in the usual manner, are retained by the process, an investigation of which is to form the subject of the present paper.

The problems on which we were engaged in the preceding Memoir were the following:—1°, The complete determination of the velocity of transmission of a wave in a fluid of any depth, provided the depth is uniform throughout; 2°, an application of the hypothesis of parallel sections to the problem in its more complicated form, in which the depth is variable in the direction of the breadth of the canal; 3°, The investigation of the motion of a solitary wave. We propose in the following pages to continue the same subjects, and to add the more difficult problem of initial motion.

In 1832 or 1833, a peasant, in felling a tree in the forest about forty miles above Degersfors, laid bare a substance strongly resembling meal, which, tempted by its appearance, he baked with a mixture of rye-flour, and used as bread. “All the world,” says Mr Laing, “of this and the next parish, flocked to the spot to take their part of this extraordinary blessing of meal, produced in the earth at a time when they were reduced to bark bread. The functionaries of the district at last heard of it, and gave orders that it should not be used until they had ascertained that it was safe. Some of it was sent to Stockholm to be analyzed.” Mr Laing has stated, in his Tour, that it was said to consist chiefly of finely pulverised flint and felspar, with a residuum of organised matter; but the proportions, or the regular analysis, he could not learn.

Since my last communication to the Society on this subject, I have continued my experimental investigation of the proposed law which limited the direct action of the voltaic current to the solvent, in solutions of primary combinations of elementary bodies in the more important solvents. All my farther researches have confirmed the rule in regard to aqueous solutions; and I feel now fully convinced of its truth, although, in the mean time, I have had occasion to see a different view advocated by some other experimenters, to whose opinions I shall afterwards advert. Neither have I seen any grounds for altering my views in regard to alcoholic solutions. In regard to ether, some experiments which I shall afterwards mention, have satisfied me that it would be improper at present to include that solvent in any general rule.

The design of the processes described in this memoir was to decompose the bicyanuret of mercury at such a temperature, and under such a degree of pressure, as to secure the simultaneous extrication of the two equivalents of cyanogen, or their elements, in the expectation that they should come off united, and produce the interesting compound of nitrogen and carbon, isomeric with cyanogen, Paracyanogen : And that result was sought in the belief that it would illustrate the chemical theorem of the existence of bodies which, though composed of the same elements in the same proportions, yet differ as widely from each other in chemical properties and mechanical conditions, as one element differs from another.

It is a general belief that Man, in his supposed progress from Savage to Civilized Life, has passed through three distinct stages or periods, each one leading a step forward in the road to social improvement. These stages are asserted to be, 1. The Hunter State; 2. The Pastoral State; and, 3. The Agricultural State. Allusions to these different stages crowd the pages of the historian, the philosopher, and the poet; and arguments are founded on, and deductions drawn from, these states of existence, as if they were ultimate truths, neither to be discussed nor dissented from. It is the object of this paper to question the existence of these separate states, their necessary connection with one another, and the end to which ultimately they are supposed to lead.

Multiplices Solariorum species, genus testaceorum constituentes, ad Turbinacea Lamarck, ad Gasteropoda Cuvier, pertinens, quæ in geologicis Italiæ stratis reperiuntur, monographico modo investigare fortasse præstat. Ratio nec ambigua; variæ enim dubitandi rationes vigebant, tum circa numerum et nomina specierum, tum circa earundem citationes, et auctorum dissensiones, nec non potissimum circa relationes specierum quæ in Italicis divisionibus supracretaceæ formationis adsunt, sive in se spectatis, sive prout cum viventibus conveniunt aut discrepant.

Having been requested to act on a Committee of the British Association, appointed to devise and apply methods for measuring the comparative intensity of earthquake shocks, and having been shewn several ingenious contrivances by Mr David Milne (who suggested the inquiry) Lord Greenock, and other persons, an apparatus occurred to me which should unite the requisites of Simplicity, Compactness, Comparability, and an easy adjustment of Sensibility according to circumstances.

Mr Milne had not failed to distinguish the ends for which instruments (which for obvious reasons were to be self-registering) ought to be devised, such as the measurement of horizontal concussions, of vertical elevation, and of heaving or angular motion of the surface. It is no part of my present object to consider the probable movements of the soil in earthquakes. I limit myself to the description of a single instrument intended to measure lateral shocks, such as are experienced by objects placed upon a table which is abruptly shoved forwards.

In a Memoir on the Preparation of Paracyanogen submitted to the Royal Society some weeks ago, I laid down the proposition, that two equal and similar molecules may enter into the state of chemical union, the combination produced being indissoluble by every known agent of analysis; and I endeavoured to establish this proposition partly on certain abstract physical considerations, and partly by a series of experiments on the production of paracyanogen by the decomposition of the bicyanide of mercury under pressure and at high temperatures.

The genus Amphioxus was instituted by Mr Yarrell for the reception of a singular little animal which he received from Mr Couch. The characters of this genus, as given in the History of British Fishes, are, “Body compressed, the surface without scales, both ends pointed; a single dorsal fin extending the whole length of the back; no pectoral, ventral, anal, or caudal fins; mouth on the under part of the head, narrow, elongated, each lateral margin furnished with a row of slender filaments.”