Messrs. Dunlop and Sulivan are discussed in this view; and the value of results obtained under circumstances of due precaution is pointed out by their success.

The position of the lines on the land portion of the map is derived from 120 determinations in various parts of Europe, Africa, and America, between the years 1834 and 1839, of which about the half are now first communicated.

The series of Messrs. Dunlop and Sulivan contain also observations of the magnetic intensity made at sea; Mr. Dunlop's by the method of horizontal vibrations, and Lieut. Sulivan's by the instrument and method devised by Mr. Fox. The degree of precision which may be obtained by experiments thus conducted, is shown by the comparison of these observations with each other, and with the isodynamic lines previously derived from observations made on land.

The first section of this paper concludes with discussions on the relative positions of the lines of least intensity and of no dip, and of the secular change which the latter line has undergone in the ten years preceding 1837.

In the second section, the observations of Mr. Dunlop are combined with recent observations on the coasts of Australia, by Captains Fitz Roy, Bethune, and Wickham, of the Royal Navy, to furnish a first approximation to the position and direction of the isodynamic lines over that portion of the Indian ocean which is comprised between the meridian of the Cape of Good Hope and New South Wales.

"

A paper was also in part read, entitled, Experimental Researches in Electricity, seventeenth series. By Michael Faraday, Esq. D.C.L., F.R.S., &c. On the source of power in the Voltaic

Pile."

March 26. The reading of a paper, entitled, "Researches in Electricity, Seventeenth Series: on the source of power in the Voltaic Pile." By Michael Faraday, Esq., D.C.L., F.R.S., &c., was resumed and concluded.

In a postscript, the author states that he has since found a passage in Dr. Roget's treatise on Galvanism, in the Library of Useful Knowledge, published in January 1829, in which the same argument respecting the unphilosophical nature of the contact-theory is strongly urged.

"Were any further reasoning necessary to overthrow it, (namely, the voltaic theory of contact) a forcible argument might be drawn from the following consideration. If there could exist a power, having the property ascribed to it by the hypothesis, namely, that of giving continual impulse to a fluid in one constant direction, without being exhausted by its own action, it would differ essentially from all the other known powers in nature. All the powers and sources of motion with the operation of which we are acquainted, when producing their peculiar effects, are expended in the same proportion as those effects are produced; and hence arises the impossibility of obtaining by their agency a perpetual effect, or, in Phil. Mag. S. 3. Vol. 17. No. 108. Aug. 1840. L

other words, a perpetual motion. But the electro-motive force ascribed by Volta to the metals when in contact, is a force which, as long as a free course is allowed to the electricity it sets in motion, is never expended, and continues to be exerted with undiminished power, in the production of a never-ceasing effect. Against the truth of such a supposition the probabilities are all but infinite." § 113, p. 32.

April 2.-The following papers were read, viz. :

"Additional note to the Eleventh Series of Researches on the Tides." By the Rev. William Whewell, B.D., F.R.S., &c.

As an appendix to his former memoir on tide observations*, the author gives in the present paper the results of observations made at Petropaulofsk, in the bay of Avatcha, in Kamtchatka, lat. 53° 1' N., long. 158° 44' E., by the officers and men of the Seuivine, commanded by the present Russian Admiral Lütke; and which were conducted with great care and perseverance. The height of the surface was noted every ten minutes, both day and night, and when near its maximum every two minutes.

It appears from these observations that the high water is affected in its time by a very large diurnal inequality, reaching the enormous amount of above four hours; while its height is only slightly affected by an inequality of that kind; the greatest alternate inequalities of height were something more than a foot. In the low waters, there appears a much smaller inequality in the times, seldom amounting to more than one hour; but with regard to height, the diurnal inequality is much larger than that for high water, reaching to three, or even four feet; and this in a tide of which the whole rise, from the lowest to the highest, rarely exceeds five feet. The theory of these phænomena is then discussed.

The results of another series of observations made in July 1827, at the port of Novo-Arkhangelsk, in the island of Sitkhe, in Norfolk sound (lat. 57° 2' N., long. 135° 18' W.), are also given, and their theory considered.

A paper was also in part read, entitled, "On the Nervous System." By Sir Charles Bell, F.R.S.

April 9. The reading of a paper, entitled, "On the Nervous System." By Sir Charles Bell, F.R.S., was resumed and concluded. The author adverting to the papers on the nervous system, which he presented to the Royal Society nearly twenty years agot, recapitulates the train of reasoning which originally led him to the inquiries in which he has been so long engaged, on the different functions of different classes of nerves, and adduces various pathological facts in corroboration of the correctness of the views he then entertained. With regard to the spinal nerves, cases are related

* [Abstracts of Mr. Whewell's former Researches on the Tides will be found in the Lond. and Edinb. Phil. Mag., vol. xv. p. 316.]

↑ [See Phil. Mag., first series, vol. lxiv. pp. 41.119.353. 442; and Lond. and Edinb. Phil. Mag., and Annals, 2d series, vol. vi. p. 135; also Lond. and Edinb. Phil. Mag., vol. vii. p. 138.]

where, in consequence of disease of the bodies of the vertebræ, the anterior columns of the spinal chord, and anterior roots of the nerves were affected, and paralysis of the muscles to which those nerves are distributed was produced, while the posterior column of the cord was uninjured, and the sensibility unimpaired. The author next considers the respiratory system of nerves, which he regards as being both muscular and sensitive, and describes as arising from a tract of the spinal cord, on the outside of the corpus olivare, and anterior to the processus ad cerebellum; and which constitute columns having no decussations with one another, as is the case with the other systems. The conclusion he originally formed, that both the phrenic and the spinal accessory nerves are provided for motion, which he had deduced from the anatomical fact of the former taking a direct course to the diaphragm, and the latter a circuitous one for the purpose of associating the muscles of the respiratory organs with those which act on the chest, is, he thinks, amply confirmed by subsequent experiments. He concludes his paper with some remarks on the supply of blood to the respiratory system of nerves, which supply, being derived from branches of the vertebral arteries, affords an explanation of several pathological phenomena.

A paper was also read, entitled, "On the constitution of the Resins. Part IV."* By James F. W. Johnston, Esq., M.A., F.R.S. This paper contains the account of the continuation of the author's previous researches into the constitution of the resins, both as they occur in nature, and as they appear when extracted from the natural products by the agency of alcohol or æther. The great difficulty in this inquiry is to determine when the resin to be analysed is obtained in its normal state; and the author has endeavoured in each case to ascertain this point by repeated analyses of the resins prepared under different conditions. He thus arrives at the conclusion, that the resin of scammony extracted from crude scammony by alcohol, and heated to 260° Fahr., is represented by C40 H33 020, containing the largest amount of oxygen of any resin hitherto analysed. The resin of jalap, obtained by evaporating the alcoholic extract, and afterwards boiling it in water, is represented b C40 H34 018, and in the amount of oxygen it contains is only surpassed by the resin of scammony. It is interesting to remark that these two resins in their effects on the animal economy are as nearly related as these formulæ show them to be in chemical constitution.

The resin of labdanum, extracted by alcohol from the crude labdanum and evaporated, gave the formula C40 H33 09; but this extract, softened in the air and water, took up from it a bitter substance of a brown colour. After boiling in water, the pure resin is represented by C40 H33 07.

The Berengela resin, previously analysed by the author before he was aware of the conditions necessary to be attended to in order to

* [See Lond. and Edinb. Phil. Mag., vol. xv. p. 327, for the former papers.]

148

obtain a resin in its normal state, is expressed by the formula C40 H30 O7; and the resin of Retin asphalt, also previously analysed by the author, by C40 H27 06.

The resin of ammonia, extracted by alcohol from the crude gum resin, is represented by C10 H2; 09; the resin of opoponax by C40 H5 014; and that of assafœtida by C40 H26 Ο 10.

A striking relation appears between the formulæ for the resins of ammonia and assafœtida, the former being C40 H95 O, the latter C40 H26 010, as if the latter were merely a hydrate of the former. The author considers this relation, and concludes that it is only apparent, and that probably in neither of the resins does any of the hydrogen exist in combination with oxygen in the state of water.

This leads the author to inquire into the general action of a slightly elevated temperature on the resins, and he concludes that in all cases when a resin in its normal state is heated a few degrees above its melting point, it begins to suffer partial decomposition, accompanied by the solution of water, and always by more or less of a volatile, generally oily compound, sometimes containing less and sometimes more oxygen than the resin which has been subjected to heat. In the case of some resins, especially such as are agreeably fragrant, and are expressed by the second of the author's general formulæ C40 H94+x O, benzoic acid is one of the products of decomposition at a moderate temperature. Thus the resin of dragon's blood gives only a trace of benzoic acid, with water and a red volatile compound; while the resin of benzoin gives much benzoic acid. Some resins give off volatile matters and diminish in weight long before they reach the fusing point; as is the case with the resin of benzoin, of which the melting point is high. With regard to the special action of such temperatures in altering the atomic constitution of the resins, the author finds that each resin undergoes a change, probably peculiar to itself, and probably depending on the nature of the organic radical it contains. Thus, the formula for the resin of retin asphalt (=C10 H27 O6) by prolonged heating at the melting point becomes C40 Ha O. Ammonia resin (=C40 Hos O2) by heating at 270° Fahr. approaches to C45 HO,; there being, however, a slight excess of oxygen, and water not being the only volatile compound driven off.

5

The resin of opoponax, when thus heated the hydrogen, as in that of retin asphalt, remains nearly constant = C40 H25 014, approaching to C40 H33 012. The same is the case with the resin of assafoetida (=C40 H25 010), which by prolonged heating at about 250° Fahr., becomes C40 H96 O. These observations when multiplied are likely to assist materially in leading to rational formulæ, expressive of the molecular constitution of the resins.

G

In reference to the general questions, with a view to the solution of which the author undertook this investigation, he concludes:

1. That the resins are not to be considered as different compounds of one and the same radical, but rather as analogous groups of compounds of analogous radicals.

2. That as far as our present knowledge extends, all the true resins are capable of being represented by irrational formula, in which C40 is a constant quantity.

3. That the analyses contained in the present paper render necessary a slight modification in the general formulæ previously announced. The formula for the group of which colophony is the type, being C40 H32 + xOy; and that for the group of which gamboge or dragon's blood is the type, being C40 H24 + xOy.

The author announces a further continuation of these researches, in which the constitution of other resins will be given, and the relations of the resins to certain chemical reagents will be explained and illustrated.

The Society then adjourned over the Easter Recess, to meet again on the 30th of April.

GEOLOGICAL SOCIETY.

[Continued from p. 74 of the present volume.]

Dec. 18, 1839.-A paper was first read, entitled "Description of the fossil remains of a mammal, a bird, and a serpent, from the London clay," by Richard Owen, Esq., F.R.S., F.G.S.

The author commences by observing, that only a few months had elapsed since the highest organic animal remains known to exist in the London clay were those of reptiles and fishes; and that the danger of founding conclusions in Palæontology from negative evidence was perhaps never more strikingly illustrated than by the fact, that the first scientifically determined relic of a warm-blooded animal from that formation proved to belong to the highest order of that class, if man be excepted; and that besides those quadrumanous remains, there have since been discovered in the London clay underlying the coralline crag, near Kyson, in Suffolk, teeth of cheiroptera, and of a species probably belonging to the marsupial order*. Mr. Owen then proceeds to describe the fossils, the immediate objects of the communication.