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Royal Institution of Great Britain.

1862.

GENERAL MONTHLY MEETING,

Monday, December 1, 1862.

WILLIAM POLE, Esq. M.A. F.R.S. Treasurer and Vice-President,

in the Chair.

George Berkely, Esq.
Michael Smith, Esq.
John Ware Stephenson, Esq. and

Major Henry Strachey, were elected Members of the Royal Institution.

August F. Andresen, Esq. and

Samuel Scott, Esq. were admitted Members of the Royal Institution.

Sir RODERICK I. MURCHISON, D.C.L. F.R.S., was elected a Manager, in the room of Sir B. C. BRODIE, Bart., deceased.

The PRESENTS received since the last Meeting were laid on the table, and the thanks of the Members returned for the same : viz.

FROM Secretary for War (through Sir H. James, the Editor )—Abstracts of the Meteoro

logical Observations taken at the Stations of the Royal Engineers, 1860-61.

4to. 1862. American Academy of Arts and Sciences-Memoirs, Vol. VIII. Part 1. 4to. 1861.

Proceedings, Vol. V. Nos. 31-48. 8vo. 1861-42. American Philosophical Society-Proceedings, Nos. 62, 64, 65. 8vo. 1859-62. Boston Society of Natural History, U.S. --Proceedings, Vol. VIII. Nos. 5-20;

Vol. IX. Nos. 1-3. 8vo. 1861-2. Brande, William Thomas, Esq. F.R.S.- Chemistry. By W. T. Brande and A. S.

Taylor. 16to. 1863.
Chemical Society--Journal, No. 67. 8vo. 1862.
Cheney, T. A. Esq.- Report on the New York State Cabinet of Natural History

and Antiquities. 8vo. 1960.
Editors - Artizan for November, 1862. 4to.
Athenæum for November, 1862. 4to.
Chemical News for November, 1862. 4to.
Engineer for November, 1862. fol.
Horological Journal, No. 52. 8vo. 1862.

Vol. IV. (No. 37.)

Editors (continued )- Journal of Gas-Lighting for November, 1862. 4to.

Mechanics' Magazine for November, 1862. 8vo. Medical Circalar for November, 1862. 8vo. Practical Mechanics' Journal for Noveniber, 1862. 4to. Technologist for November, 1862. 8vo. Franklin Institute of Pennsylvania-Journal, No. 442. 8vo. 1862. Geographical Society, Royal-Proceedings, Vol. VI. No. 5. 8vo. 1862. Geological Institute, Vienno-Jahrbuch, 1861-2. No. 3. 8vo. 1862. Geological Society-Quarterly Journal, No. 72. 8vo. 1862. Geological Society of Dublin—Journal, Vol. IX. Part 2, 8vo. 1861-2. Graham, Lieut.-Col. J. D. U.S.—Report on Harbours of Lake Michigan, &c.

8vo. 1862. Held, Joseph, Ph.D. LL.D. (the Author)—Staat und Gesellschaft. Band I. 8vo.

Leipzig, 1861. Liverpool Literary and Philosophical Society, Proceedings, No. 16. 8vo. 1862. Medical and Chirurgical Society, Royal-Medico-Chirurgical Transactions. Vol.

XLV. 8vo. 1862. Newton, Messrs.-London Journal (New Series) for November, 1862. 8vo. North of England Institute of Mining Engineers—Transactions, Vols. X. and XI.

8vo. 1861-2. Petermann, A. Esq. (the Editor)-Mittheiluugen aus dem Gesammtgebiete der

Geographie. No. 10. 4to. 1862.
Photographic Society - Journal, No. 127. 8vo. 1862.
Royal Society of Edinburgh-Transactions, Vol. XXIII. Part 1. 4to. 1861–2.

Proceedings, Nos. 56-58. 8vo. 1861-2.
Royal Society of Literature-Transactions, Vol. VII. Part 2. 8vo. 1862.
Smithsonian Institution, Washington, U.S.–Smithsonian Miscellaneous Collections,

Vols. I. II. III. IV. 8vo. 1860-2.
Smithsonian Report, 1860. 8vo.

Results of Meteorological Observations, 1854-9. Vol. I. 4to. 1861. St. Petersburg Imperial Academy of Sciences - Mémoires, Tome IV. Nos. 1-9.

4to. 1861-2. Bulletins, Tome IV. Nos. 11-14. 4to. 1861-2. Tylor, Alfred, Esq. M.R.I.-Tylor, Edward B.: Anahuac; or, Mexico and the

Mexicans. 8vo. 1861. Vereins zur Beförderung des Gewerbsleisses in Preussen-Verhandlungen, Juli und

Aug. 1862. 4to. Wiener, M. Charles, Statuaire et Medalleur de S. M. le Roi des Pays-Bas

Medallion of the Prince Consort.

1863.

SPECIAL MEETING OF THE MEMBERS,

Monday, January 19, 1863. WILLIAM POLE, Esq. M.A. F.R.S. Trseaurer and Vice-President,

in the Chair. The Chairman stated, that the Managers, desirous that His Royal Highness the PRINCE OF WALES should become an Honorary

Member and the Vice - Patron of the Institution, had requested Professor Faraday to communicate with His Royal Highness on the subject, which had been done by him in the following terms :

“ROYAL INSTITUTION, 5th January, 1863. “ To His Royal HIGHNESS THE PRINCE OF WALES. “ May it please Your Royal Highness,

“The President, Secretary, and Managers, remembering the great grace which was done to the body, when the late Vice-Patron, His Royal Highness the Prince Consort, with yourself and the Prince your brother, favoured our Lectures with your presence, have requested me to express the hope they entertain, that Your Royal Highness will allow of your election into the position then filled by your admirable and much-loved Father. It is because I had the honour of speaking at that time in your presence, that the authorities here think I may not be unacceptable as the channel through which their earnest desire may be made known. Our most honoured Queen is our Patron; and that we may have your Royal Highness as Her and our Vice-Patron is the most earnest wish of our hearts. Remembering the past, we hope for this great grace for the future. “ With the deepest feelings of respect, I venture to sign myself,

“Your Royal Highness's faithful servant,

“M. FARADAY.” The Chairman further stated, that the following reply had been received from Lieut.-General Knollys, Comptroller of the Household and Treasurer to the Prince of Wales :“DEAR SIR,

“SANDRINGHAM, 9th January, 1863. “I am directed by the Prince of Wales to acknowledge the receipt of your Letter, conveying the request of the authorities of the Royal Institution that His Royal Highness would allow Himself to be elected as its Vice-Patron, in the room of His lamented Father.

“ His Royal Highness has desired me to say, that it will be a great gratification to Him, to fill so distinguished a post, and to occupy a position filled by that beloved Parent, however unequal His Royal Highness may feel to take His place. It will be no less satisfactory to Him to be in any way associated with the interests of Science. And His Royal Highness has commanded me particularly to assure you of the peculiar pleasure it will give Him to meet you again, where He has listened to you before, and derived so much instruction from your Lectures. “I have the honour to remain, dear Sir, very truly yours,

“W. KNOLLYS. “M. FARADAY, Esq."

Whereupon H.R.H. the PRINCE OF WALES was proposed, and unanimously elected Honorary Member, and then, by acclamation, was elected the Vice-Patron of the Royal Institution.

WEEKLY EVENING MEETING,

Friday, January 23, 1863.

Sir HENRY HOLLAND, Bart. M.D. D.C.L. F.R.S. Vice-President,

in the Chair.

John TYNDALL, Esq. F.R.S.
PROFESSOR OF NATURAL PHILOSOPHY, ROYAL INSTITUTION.

On Radiation through the Earth's Atmosphere.

NOBODY ever obtained the idea of a line from Euclid's definition that it is length without breadth. The idea is obtained from a real physical line drawn by a pen or pencil, and therefore possessing width; the idea being afterwards brought, by a process of abstraction, more nearly into accordance with the conditions of the definition. So also with regard to physical phenomena; we must help ourselves to a conception of the invisible by means of proper images derived from the visible, afterwards purifying our conceptions to the needful extent. Definiteness of conceptions, even though at some expense to delicacy, is of the greatest utility in dealing with physical phenomena. Indeed it may be questioned whether a mind trained in physical research, can at all enjoy peace, without having made clear to itself some possible way of conceiving of those operations which lie beyond the boundaries of sense, and in which sensible phenomena originate.

When we speak of radiation through the atmosphere, we ought to be able to affix definite physical ideas, both to the term atmosphere and the term radiation. It is well known that our atmosphere is mainly composed of the two elements, oxygen and nitrogen. These elementary atoms may be figured as small spheres scattered thickly in the space which immediately surrounds the earth. They constitute about 994 per cent. of the atmosphere. Mixed with these atoms we have others of a totally different character; we have the molecules, or atomic groups, of carbonic acid, of ammonia, and of aqueous vapour. In these substances diverse atoms have coalesced to form little systems of atoms. The molecule of aqueous vapour, for example, consists of two atoms of hydrogen united to one of oxygen ; and they mingle as little triads among the monads of oxygen and nitrogen, which constitute the great mass of the atmosphere.

These atoms and molecules are separate ; but in what sense? They are separate from each other in the sense in which the individual fishes

of a shoal are separate. The shoal of fish is embraced by a common medium, which connects the different members of the shoal, and renders intercommunication between them possible. A medium also embraces our atoms; within our atmosphere exists a second, and a finer atmosphere, in which the atoms of oxygen and nitrogen hang like suspended grains. This finer atmosphere unites not only atom with atom, but star with star ; and the light of all suns, and of all stars, is in reality a kind of music propagated through this interstellar air. This image must be clearly seized, and then we have to advance a step. We must not only figure our atoms suspended in this medium, but we must figure them vibrating in it. In this motion of the atoms consists what we call their heat.“ What is heat in us," as Locke has perfectly expressed it, “is in the body heated nothing but motion.” Well, we must figure this motion communicated to the medium in which the atoms swing, and sent in ripples through it with inconceivable velocity to the bounds of space. Motion in this form, unconnected with ordinary matter, but speeding through the interstellar medium, receives the name of Radiant Heat; and, if competent to excite the nerves of vision, we call it Light.

Aqueous vapour was defined to be an invisible gas. Vapour was permitted to issue horizontally with considerable force from a tube connected with a small boiler. The track of the cloud of condensed steam was vividly illuminated by the electric light. What was seen, however, was not vapour, but vapour condensed to water. Beyond the visible end of the jet the cloud resolved itself into true vapour. A lamp was placed under the jet at various points; the cloud was cut sharply off at that point, and when the flame was placed near the efflux orifice the cloud entirely disappeared. The heat of the lamp completely prevented precipitation. This same vapour was condensed and congealed on the surface of a vessel containing a freezing mixture, from which it was scraped in quantities sufficient to form a small snowball. The beam of the electric lamp, moreover, was sent through a large receiver placed on an air-pump. A single stroke of the pump caused the precipitation of the aqueous vapour within, which became beautifully illuminated by the beam ; while, upon a screen behind, a richly-coloured halo due to diffraction by the little cloud within the receiver flashed forth.

The waves of heat speed from our earth through our atmosphere towards space. These waves dash in their passage against the atoms of oxygen and nitrogen, and against the molecules of aqueous vapour. Thinly scattered as these latter are, we might naturally think meanly of them as barriers to the waves of heat. We might imagine that the wide spaces between the vapour molecules would be an open door for the passage of the undulations ; and that if those waves were at all intercepted, it would be by the substances which form 994 per cent. of the whole atmosphere. Three or four years ago, however, it was found by the speaker that this small modicum of aqueous vapour intercepted fifteen times the quantity of heat stopped by the whole of the air in which

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