Mr. YATES exhibited the rare "Museum Tradescantianum," by John Tradescant, 1656; and entered into an explanation of the collection enumerated, noticing many curious things in it. He also referred to the recent renovation of the monument erected in the churchyard of Lambeth.

Mr. GRAY exhibited several drawings illustrating punishments in China.

Mr. HUNTER drew attention to Seechi's Observations on Terrestrial Magnetism, and gave a short sketch of the laws laid down by that celebrated astronomer.

Dr. THOMSON referred to the late observations of Struve on the contracting of Saturn's rings upon the body of the planet, and to observations made about a century ago; also to Seechi's reference to the drawing made by Campani in 1664.

A communication was made to the Society by Dr. INMAN, "On Spontaneous Combustion, and Suggestions for Extinguishing Fire." This paper was subsequently published by the author.

SEVENTH ORDINARY MEETING.

ROYAL INSTITUTION.-January 22nd, 1855.

JOSEPH BROOKS YATES, Esq., SEN. V.P., in the Chair.

The Council was requested to revise the list of Corresponding Members, and submit a corrected list to the Society.

The following gentlemen were balloted for, and duly elected Ordinary Members:-GEORGE ATKIN, Esq., JAMES HAKES, Esq., and A. FINLAYSON, Esq.

The CHAIRMAN read several extracts from "broad sheets" printed in 1702, entitled, "Characters of the Royal Family, Ministers of State, &c., in the French Court, written by a French nobleman to his friend in England."

Mr. J. JONES exhibited a curious specimen of Chinese paper bearing coloured designs, apparently woven like cloth, suitable for walls.

The following paper was then read:

OBSERVATIONS ON THE PHENOMENON OF ODOUR, BY THOMAS C. ARCHER, Esq.

Ir is, I believe, generally supposed that all odoriferous bodies give off particles, which, coming in contact with the olfactory organs, communicate the sense of smell to the brain. This probably is the case in some instances, but I have been led to doubt it as a general fact. If the sensation of smell resulted from the absolute contact of atoms given off by the odorous substance, it would follow as a matter of course that such circumstances as would be likely to increase the evaporation or elimination of those particles would increase their power of producing the sensation of odour; but I think I can prove that this is not always the case. For instance, many flowers are very much more fragrant when the atmosphere is moist, especially after rain, and thunder showers more particularly, circumstances which cannot be so favourable to the evolution of essential or volatile oils as hot sunshine would prove to be.

There are, too,

and

Flowers which wake when others sleep,"

“Timid jasmine buds that keep

Their odours to themselves all day;
But when the sunlight dies away,

Let the delicious secret out,

To every wind that roams about."

The words of the poet express the truth, for the fact of many flowers being odorous by night only is well known. The jessamine mentioned by the poet only posseses this quality partially, but the beautiful Enothera biennis is scentless by day, and has an exquisite odour of primroses at night. No flower, however, is so remarkable in this respect as the night-flowering stock, Matthiola trista, which, previous to the dusk of evening, is perfectly inodorous, but afterwards becomes so powerfully fragrant, that a plant carried into a room becomes oppres sively sweet. Many others might be cited, but these are sufficient to show that the odour of some plants increases when the temperature is lowered, and the fact that most plants are most fragrant after rain is too well known to require examples. Hence it follows that some plants are most fragrant upon a decrease of temperature, a condition always opposed to volatilization; and others are most fragrant when the

atmosphere is charged with moisture, a condition hostile to the ordinary hypothesis that the fragrance of plants is dependent upon the evolution of certain volatile oils, upon which the perfume depends, for the presence of water in the air is certainly calculated to prevent rather than accelerate the transmission of particles of oil. Again, if the perfume of plants depended upon the evolution of volatile atoms, that perfume would only exist as long as the life of the plant cells continued, or at all events its effect would be much diminished upon the death of the plant; such however, is not always the case,-the delicate rose, the pungent labiate plants, and a hundred others, retain their power of perfume after the death of the tissue which yields it; and strange to say, in some instances, as in the woodruff, (Asperula odorata), the perfume is only eliminated after death.

From these, and a multitude of instances of a similar kind, I am led to this conclusion:-That the combination of oxygen with certain secretions of plants, leads, both in life and death, to a peculiar variety of eremacausis or oxidation, the effects of which are transmitted to the brain through the conducting medium of the air; and that a certain quantity of moisture in the air renders it a better conductor of this chemical action.

But it will be said, we know that in some cases the result is solely attributable to the volatilization of essential oils. Witness the rinds of the various Aurantiacia, the Menthas, and other labiates, and a great variety of plants, the essential or volatile oils of which are procured in consequence of their odour. It is true that a substance may be smelled at a distance in consequence of its volatile particles being brought in contact with the olfactory organs, but this does not prove the absolute necessity of a constant elimination of atoms from odorous substances; it simply proves that some subtsances require to be nearer to the nose than others, in order that the sensation may be experienced. Perhaps I am not sufficiently clear upon this point, but let me compare the sense of taste with that of smell; it is not contended that any substance taken into the mouth is brought into absolute contact with the nerves of taste, but the sensation is communicated or conducted through the skin of the tongue, as that of feeling is also conducted by the skin of the fingers.

My theory is, that this power of conduction may also be extended to that portion of the atmosphere which intervenes between the plant cell and the olfactory membrane; or else that the intervening atmosphere itself undergoes an absolute chemical change by its contact with the active oxygenization going on in the plant cell; and this chemical change may be extended for a considerable space. In support of this

view I may also mention that many flowers and fruits, and especially also some animal products, have a totally different smell at different distances from the nose. Musk and civet are remarkable instances of this; they are very agreeable to some persons when in very slight quantities or at a distance, but to the same persons these perfumes are positively nauseous when too near, or in too large quantities. Another reason I may perhaps be allowed to advance is, that in the case of some plants it is absolutely necessary that the surrounding air must be perfectly still, or they become scentless, even though the only motion of the air be a current made by endeavouring to draw the perfume up the nose. This is particularly exemplified by the musk plant Mimulus moschatus, which it is well known has a beautifully delicate odour of musk, but if we attempt to smell it a second time we find it less perfumed, and after the third time we can perceive no odour whatever. I am of course supposing that this proceeding only occupied two or three minutes. I have still another argument to offer, and that is the remarkable fact that all the perfumes at present known may be referred to a very few types; thus the heliotrope may be taken as one type, and we find the meadow-sweet (Spiraa ulmaria), the hawthorn, the sweet scented coltsfoot, and many others closely resemble it. The violet may be taken as another type, and we find the root of the Iris florentina and a few other plants, especially some of the turpentine-producing conifers, also yield a similar odour. This would seem to imply a greater regularity of the action producing the sense of smell, than we can suppose would be caused by the radiation of atoms from so many different species.

In conclusion, I beg to remark that the most careful microscopic examination with the highest powers fail to detect the elimination of particles, although we can detect the motion of the contents of cells, and changes produced by oxygenization.

I am at present engaged in endeavouring to classify vegetable odours under well known types, and if I have the privilege at some future time of returning to this subject, I shall hope to have a large and satisfactory list of perfumes so arranged.

EIGHTH ORDINARY MEETING.

ROYAL INSTITUTION.-5th February, 1855.

ROBERT MCANDREW, Esq., F.R.S., F.L.S., V.P., in the Chair.

The following Gentlemen were balloted for, and duly elected members: JOHN WYBERGH, Jun. Esq., and F. POTTS, Esq., Chester. Mr. MARRAT exhibited several rare mosses, one of them being new, from this neighbourhood.

A communication was made to the Society by J. T. Towson, Esq.,

ON THE SOLAR RAY.

AFTER explaining the two theories of propulsion and undulation, he assumed, without adopting, the former. The solar ray had been divided into seven colours, but it was now believed there were only three primary ones-red, yellow, and blue. He explained the respective properties of the several colours, and their possession of light, heat, and actinism, which could be taken separately or collectively. He noticed the experiments which had been made to shew the varying effects of the several rays with reference to their means of imparting heat, as also with regard to their chemical properties. The latter he distinguished as positive, neutral, and negative; comparing their relative effects on each other to acid, water, and alkali; the middle ray being capable of diluting, but not of neutralising, either of the extremes, which, however, would neutralise each other. He applied these observations to photography, and explained the difference in photographic effects to arise from differences in the atmosphere, according to the time of day, the time of year, or the climate; the solar ray differing in its proportions of blue and red. He proceeded to show the influence of these several rays on the processes of vegetation, the blossoming of flowers, the ripening of fruits, &c., and concluded by remarking that such investigations tended to prove the infinite wisdom and goodness of the Almighty.