that the molecules of mineral substances should possess this power, can only be admitted upon the most rigorous scrutiny.

I have made repeated observations on several mineral substances, which Mr. Brown says are chiefly composed of these active molecules; and though in some instances I was at first persuaded that I had seen the motions of the molecules similar to those of the smallest species of Infusòria, a more careful examination proved that I was mistaken, and that the motions were derived from causes that had not been properly appreciated. In these experiments it is absolutely requisite to employ fresh-distilled or fresh-boiled water. The Thames water and water in cisterns generally contain numerous animalcules. I chiefly made use of single lenses from to of an inch focal length, varying in magnifying power, from 100 to 220 times in linear dimensions: the use of the compound microscope is, I think, inadmissible in such delicate observations. With the lowest of the above-mentioned powers, a particle less than, part of an inch in diameter is distinctly perceptible, and the form of a particle of twice that diameter may be observed. To make use of higher powers than what are absolutely required, renders the examinations more difficult, and the result more uncertain.

To obtain glass in a highly comminuted state, I took the powder-blue used by laundresses, which I still farther triturated. The small portion of the oxide of cobalt which enters into the composition of this glass, could not be supposed to paralyse the action of the molecules, as all the metals that can be reduced to powder are said to contain these active molecules.

By making use of powder-blue, I had the advantage of seeing when all the larger particles were deposited. Among other substances which I more particularly examined, were finely powdered adhesive slate, mountain cork, quartz, flint, and kaolin, from a specimen of the best kind used in the manufacture at Sevres, given me by M. A. Brongniart. When a drop of water containing any of these substances was placed under the microscope, I perceived particles in motion, which continued for some time, and then was scarcely discernible, but on laying my hand upon the table the motion recommenced, and was evidently produced by a current in the drop; although many particles appeared to be more influenced by it than others, which occasioned a change in their relative positions. Hence I became convinced, that in order to make the experiment

According to Sir William Herschell, though an object which subtends a visual angle less than a minute may be perceived, yet, to ascertain the form of it, it should subtend two minutes and a half.

properly, the microscope should be placed on a support not liable to be affected by vibrations of any kind, and I therefore placed the instrument on a support made for a telescope stand, so constructed as to prevent vibration when examining the more delicate double stars. I found that even the pulsation of my body occasioned an oscillatory motion of the particles, when the microscope was placed upon a table. After repeated trials, I became satisfied that whatever motions may appear to take place among the particles, for some time after the drop of water is first placed under the microscope, they will soon subside, if not kept up by agitation from external 'causes. In London, as an excellent practical philosopher, the late William Nicholson, justly observed, it is scarcely possible to avoid the effects of vibration; this may be seen by the continual tremours visible on the surface of mercury placed in a basin. Now, if the particles of dust that fall on the surface of the mercury could be brought under a powerful microscope, they would appear in constant motion. Let us suppose the mercury to be changed for water, a similar effect will take place, and the particles that may sink under the surface will represent the particles of dust in a single drop; and Mr. Brown informs us that the whole of the London dust is composed of active molecules. I am fully convinced, however, that their activity in a drop of water, as well as when dancing in the sunbeam, is derived from external agitation. The very force of gravity constantly drawing the particles downwards must not be overlooked, for it is not contended that the vitality of inorganic particles is sufficient to keep them permanently suspended in water. The observer's breath, and the constant evaporation of the drop, have also a tendency to produce counter-currents. A drop of water placed under the microscope, may be regarded as equal, in apparent magnitude, to a quart of the same fluid in a water-glass, and will be subject to the various currents that may be produced by agitation in the larger quantity; but the slightest movement which occasions a displacement of the particles, even the one-thousandth part of an inch will, under a high magnifying power, make them appear to perform a long voyage. Some of the animalcules discovered by Loewenhoeck, the motions of which excited so much surprise, he informs us, never travelled farther than a hair's breadth.*

It is highly improbable that we shall ever be able to reduce mineral substances to their ultimate molecules by pulverisation.

* Hicce progressus non majus habebat spatium quam quod capilli' diametrum æquaret.

Their essential qualities remain the same after pounding as before; and, could we construct microscopes that would magnify twenty thousand times in linear dimensions, we should see in pounded quartz, flint, &c., fragments and pebbles, the size of walnuts, exactly resembling those of the same minerals at the foot of a mountain, and it is difficult to believe that they would gain active moving powers by simple immersion in water. Still the philosophical world is greatly indebted to Mr. Brown, for having directed the attention of naturalists to this curious subject. About ten years ago, I was informed that Mr. Bywater, an ingenious optician, now residing in Liverpool, had discovered moving animalcules in coal-ashes, pounded marble, and other mineral substances. Little interest was then excited by the supposed discovery, it required an eminent naturalist like Mr. Brown, whose merits are well known, and highly appreciated in his own country and on the Continent, to direct public attention to statements so much at variance with our preconceived notions of matter. If, contrary to my expectation, after all due caution in the observations, it should be finally esta blished that mineral substances are composed of active molecules, what new views of nature will the discovery unfold! Beds of siliceous sand, like those on our Hampstead Heath, are only awaiting a further process of trituration, to be awakened into life by the torrent that shall bear them into the ocean; and the geologist, while he contemplates the organic remains of a former world embedded in solid rocks, must regard the rocks themselves as the parents of future living beings. But who shall presume to say that we have at present discovered all the properties which the Creator has communicated to material substances? It should be borne in mind, that, less than a century since, latent heat, electric and galvanic energy, and crystalline polarity were unknown as important agents in nature; and that philosophers attempted to explain the phenomena of thunder-storms, and even of vital action, on mechanical principles. It will not be denied that many important processes take place in the mineral kingdom, which cannot now be explained by the agency of known causes, but await the discovery of other principles for their satisfactory elucidation.

As it is probable that many persons may be desirous of entering this new field of enquiry, it will materially assist them in forming an accurate judgment of what they observe, to provide pepper water, and other vegetable or animal infusions, that they may from time to time compare the motions of the real Animalcula infusòria with those of the supposed active molecules; and, if modern philosophy did not disdain to profit by the illustrations which common life frequently offers, I would re

commend them to look attentively at the bubbles, or the crumbs that float on the surface of a basin of tea, and they will soon be convinced, that change of relative position is not a sufficient proof of spontaneous motion or vitality. I am, Sir, yours, &c.

Hampstead, Feb. 29. 1829.

ROBT. BAKEWELL.

PS. Since the above was written, I have most carefully re-examined various mineral and inorganic substances, without discovering any proper motion of the molecules if the water was recently boiled. When I used unboiled water, I was once or twice deceived by an apparent motion which, I am convinced, was caused by animalcules previously existing in the water. R. B., Feb. 20.

ART. II. Anecdotes of a Diana Monkey. By Mrs. BOWDICH. Sir,

ALTHOUGH anecdotes of monkeys are as numerous as the beings to whom they owe their origin, although they are brought forward to all ages, and at all times, still I have observed that no one gets tired of them, that their histories or portraits create an interest common to all human beings, of whatever race, or in whatever situation. The negro delights in relating the wonders or rogueries they perform, and the saying, "that monkeys could talk if they liked, only they are afraid white men would make them work if they did," is every where to be heard among the more indolent inhabitants of the tropics. English men, women, and children resemble their black brethren: and there is yet another feeling in which the most savage and the most refined seem to agree, it is the dislike, or mortification, call it what you will, which we feel in seeing how nearly they resemble ourselves. There was a

restless, tormenting, and agile creature on board a vessel in which I sailed up an African river, who was incessantly teasing and hovering about me. If I called another, he was sure to leap across the deck, and come to perform that which the other would have done much better. I never thought myself quite alone, but this fellow's head was sure to start from some unexpected corner; and one day, wearied with his officiousness, I pointed to a black monkey sitting opposite to us, and said to him," Rapoynda, that is your brother." Kind words, presents, nought availed me afterwards, for I was never forgiven. The same feeling might be traced in a very different form, when a friend of mine pulled me away from the contem

plation of Landseer's admirable picture*, exclaiming, "How can you look at that so long? Such things ought never to have been made, and I am sure ought never to have been painted." I obeyed, but the recollection of Rapoynda flashed across me. After this I will not apologise for intruding an old ship companion of mine on your notice, although he belongs to the never failing theme of monkeys. He was a native of the Gold Coast, and was of the Diana species (Símia Diàna). (fig. 3.) He had been

purchased by the cook of the vessel in which I sailed from Africa, and was considered his exclusive property. Jack's place then was close to the cabooce; but as his education progressed, he was gradually allowed an increase of liberty, till at last he enjoyed the range of the whole ship, except) the cabin. I had embarked with more than a mere womanly aversion to monkeys, it was absolute antipathy; and although I often laughed at Jack's freaks, still I kept out of his way, till a circumstance brought with it a

3

closer acquaintance, and cured me of my dislike. Our latitude was three degrees south, and we only proceeded by occasional tornadoes, the intervals of which were filled up by dead calms and bright weather. When these occurred during the day, the helm was frequently lashed, and all the watch went below. On one of these occasions I was sitting alone on the deck, and reading intently, when, in an instant, something jumped upon my shoulders, twisted its tail round my neck, and screamed close to my ears. My immediate conviction that it was Jack scarcely relieved me but there was no help; I dared not cry for assistance, because I was afraid of him, and dared not obey the next impulse, which was to thump him off, for the same reason, I therefore became civil from necessity, and from that moment Jack and I entered into an alliance. He gradually loosened his hold, looked at my face, examined my hands and

*"The Monkey who had seen the World."