prepared a silicious fluid for the purpose of crystallisation. He heated a flint to a white heat, and then plunged it in water to pulverise it. The silex, thus reduced, was saturated to excess with muriatic acid. The mixture was placed in a jar-a piece of flannel was suspended in it, one end of which extended over the side, and thus, by capillary attraction, the liquor was slowly filtered, fell into a funnel, and thenee dropped on a piece of iron-stone from Mount Vesuvius, upon which were laid the two wires connected with either pole of the battery. We should state that the ironstone had been previously heated to a white heat, so that no germs of life could have existed upon it. Mr. Crosse made his daily observations of the wires to discover the beginning of the process of crystallisation. On the 14th day he saw some small white specks upon the stone. Four days afterwards they had elongated, and assumed an oval form. He concluded that they were incipient erystals. Great was his surprise on the 22d day to find eight legs projecting from each of these white bodies; still he could not believe that they were living beings. But on the 26th day his surprise was complete; there could be no doubt they moved, they fed, they were perfect insects. 18 or 20 of them have since appeared. Many persons have seen them, but there is no record of such an insect.

It is in form something like a mite. It has eight legs, four bristles at the tail, and the edges of the body are very bristly. Its motions are visible to the naked eye-its colour is gray-its substance is pulpy. It appears to feed upon the silicious particles in the fluid.

The most extraordinary circumstance in this phenomenon is the nature of the fluid in which this insect lives and thrives. The acid instantly destroys every other living being.

But a second trial has confirmed the fact beyond a doubt. Another portion of silex was prepared in the same manner, and reduced to a gelatinous form, but without the acid. A coil of silver wire was suspended in it from one of the poles of the battery, and the other pole was also immersed, so as to send through the mass an incessant stream of the electric fluid. About three weeks afterwards Mr. Crosse examined the poles to search for crystals, and in one of the coils of wire he found one of these strange insects. This proves that it is produced from the silex and not from the acid.

Mr. Crosse, with his usual modesty, has contented himself with stating the fact, without attempting to account for it. He is in correspondence with Professor Buckland upon the subject, and the learned professor has suggested an explanation, which it will be for future observers, by repeated experiments, to confirm. We should state, that the in

sects were principally found at the negative pole of the battery.

A German naturalist has recently discovered that silicious and other rocks are chiefly composed of the remains of insects. May not the germs of some of them, released from their prison-house, and placed in a position favourable to the development of vitality, have sprung to life after a sleep of thousands of years?

NOTES AND NOTICES.

Gratuitous Lecturing.-In a series of Resolutions just adopted by the Gresham Lecturers to express their very resolute resolution not to move, it is stated, that during the past year the number of their auditors has amounted to 1900, and that the average number of persons who have attended the most popular series, the Astronomical, has been 64, which leaves 18 for each of the rest. This number appears any thing but satisfactory, 'in a capital where five or six hundred persons are often found willing to purchase the privilege of hearing a lecture on the very subjects in which the Gresham establishment proffers instruction gratis. But strange as it may seem, in Paris itself, the very metropolis of accommodation of this kind, where the most eminent scientific characters of the country deliver lectures with the doors open to all who choose to enter, the results do not present a very striking contrast. An intelligent German traveller, Benzenberg, who visited Paris in 1804, and published an account of his observations next year, at Dortmund, resumed, on his arrival there, his "University Life," which is, he tells us in his opinion, "always and every where the happiest form into which life can shape itself," attended the most attracting lectures then delivering in the French capital. He was not only astonished at the military aspect of the lecture-rooms, in which a couple of soldiers always appeared, immoveable as a couple of statues, one on each side of the lecturer, but at the small number of persons gathered together to share a treat which was so attractive to himself. At a lecture of Lalande's, at the college of France, he found only six auditors. Those of Hauy and Fourcroy were the most popular by far, and at Hauy's he made the hundredth who attended; while at Fourcroy's he never on any occasion counted more than 112. Yet he is confirmed by Meyer (another German writer whose letters were, we believe, translated into English), in esti mating Fourcroy as a consummately eloquent and interesting speaker, as well as a man of genuine science. The Swedish traveller, Suedenstjerna, who visited Paris much about the same time, is also loud in his praise of Fourcroy, whose talents in lecturing he considered it impossible to surpass, till a few months after he heard Sir Humphrey Davy, who had just then burst into the full blaze of his fame, at the Royal Institution. It is well known that these lectures of Sir Humphrey's, to which access was difficult, were attended by eager crowds.

The assertion of Sir Humphrey Davy, that no species of plant will vegetate downwards, has lately been contradicted by an experiment made by Messrs. Lockhart and Co., florists, Cheapside, in a Narcissus, the bulb of which is placed in a large glass vase filled with water, The Narcissus is now on the point of coming into flower downwards, a large pod of bloom and several long leaves being already visible in the water.

Lighting Houses by Electricity.-Professor Meinecke, of Halle, proposes to light houses and streets by means of an electric spark, and he thinks that

this system may supersede that of gas, as giving a better light, and being more economical. His plan is to construct luminous tubes, having at intervals inetallic plates, ou which might be formed, by means of a machine, a rapid succession of electric sparks. The Professor has obtained by an operation of this kind, and from a two-feet machine, a constant light in his apartment resen bling a bright moonlight. By confining the sparks in a tube filled with rarefied hydrogen-gas, the Professor thinks it will be easy to obtain the same result on a large scale.

Analysis of Woods. Two Gerinan chemists, Messrs. Petersen and Schodler, have made elaborate experiments in order to ascertain the quantities of carbon, hydrogen, and oxygen contained in each species of wood. They have analysed 24 different kinds, and after having dried them and reduced them to powder, have taken 100 parts of each in weight, and found that the quantity of carbon in each does not vary more than from 48 to 50 per eent, the hydrogen from 5 and 1-3d to nearly 6 per cent., and the oxygen from 43 and 1-3d to 45% per cent. The proportions would be different in relation to volume; for instance, a cubic metre of oak weighs 479 lbs., while the same body of poplar weighs only 221 lbs.

French Mechanics' Institute.-A Society has been formed at Paris (says the Literary Gazette) on the plan of the London Mechanics' Institution. It was first suggested by the celebrated geometrician, Monge, and the labour of instruction is principally confided to the students of the Polytechnic School. Classes are organised to teach the prin ciples of mathematics, optics, and all the branches of natural philosophy; as also the fine arts, grammar, and languages; each class is presided over by an advanced member; and the plan is so successful, that the Society musters at the present time upwards of 1500 members. We hope the Parisian mechanics will be more fortunate in their Institution than have been the London. The tutorship of the Polytechnic scholars seems to be the most objectionable part of this scheme; we do not say this in order to detract from the merits of these youths-but from our often-expressed opinion, that such Institutions can never answer the desired end unless the members proceed upon the independent principle of themselves paying for the benefits they receive. Government direction will, no doubt, be thrust upon the Society-in France this cannot be avoided-but of individual patronage or aid we warn the Parisian Mechanics to beware-keeping the example of the London Institution before their eyes, which, from one of the most promising schemes for bettering the condition of the working mechanic, has degenerated into a mongrel concern, without any definite aim or character.

Institution for Disabled Colliers and Miners.-A correspondent of the Staffordshire Advertiser suggests the formation of a fund for the relief of disabled colliers and miners. The following is his plan:-"1. Let an In-titution (suppose we name it The Miners' Friend') be formed for the whole kingdom, with a general hospital, in some mining district, attached, for the permanent reception of a certain number and kind of disabled and destitute colliers or miners, who are members.-2. Let it be supported by the benefactions of the wealthy and charitable, and the annual subscriptions of mine owners and their workman.-3. Let tempo. rary or permanent relief be given to those members only who receive bodily injury, or are disabled, in mining concerns, with life-annuities to the families or dependents on such as lose their lives in the pursuit of their callings in mines.-4. Let all owners, masters, and workmen, of mining concerns in the United Kingdom, be invited to become members; the workmen to pay a small sum each quar

terly, and the proprietors and public to pay collectively as much, or perhaps twice as much, as the workmen pay collectively; thus laying the burden on the public, the proprietary, and the party to be benefited. I deem it impolitic to free the workmen altogether from charge, as it is imprudent to help those who will not help themselves; and a few shillings a year from each man (judging from the casualties in my own concerns for twenty years past) added to other resources would, I think, suffi ciently support the Institution. If we look nar rowly into the present importance of collieries and mining concerns, with a view to the protection and prosperity they afford to Old England, we shall find them on the one hand, what brave seamen and wooden walls are on the other; and as the sailors have their refuge at Greenwich, let not the colliers be without retreat when disabled in such laudable and beneficial service."

Trial of the New Fire-proof Dress.-At a fire (not a serious one) which occurred lately at Mr. Knight's, stationer, Basing-lane, Watling-street, the Parisian smoke-proof fire-dress was, for the first time, brought into actual service. Mr. Braidwood himself put it on, and, descending into the cellar, there remained till the fire was completely extinguished, passing through the parts where the smoke was most dense without experiencing any inconvenience. The firemen who were not so equipped were not able to remain in any part of the cellar more than ten minutes, and experienced a difficulty of breathing, and their eyes were red and 'swollen, as if they had been crying. There were two engines brought to the spot, one of which was employed in, supplying Mr. Braidwood with a continuous current of fresh air. The flames never mounted above three feet from the floor, nor was the smoke particularly dense, so that the apparatus cannot be said to have been fully tested on this occasion; but enough was done to confirm Mr. Braidwood in the opinion fo mer experiments had induced him to form of its great utility in the case of fires in cellars.

The Supplement to Vol. XXV., containing Ti tie, Table of Contents, Index, and Plate of Specimens of English Medallic Engraving by Mr. Bate was published on the 1st of December, price 6d.

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YA

MR. CURTIS'S ACOUSTIC INVENTIONS.

The application of acoustics to the purposes of civilisation has been very culpably neglected-even to the loss of what was known and practised centuries ago. Dr. Reid has had the merit of calling public attention to the subject, in as far as relates to the construction of buildings, in his public lectures and his evidence before the Commons' Committee on the New Houses of Parliament.* We have now to call the attention of our readers to another branch of the science, namely, the conveyance of sound to great distances by acoustic tunnels.

What the telescope is to the eye, acoustic tunnels would be to the ear. It appears no more wonderful that we should be able to hear at the distance of five or six miles, than that we should be enabled to see objects at that distance by the telescope, as distinctly as if we were within a few yards of them."+ Acting on this intelligent view of the subject, Mr. Curtis, one of the most skilful aurists of the day, has been led to the invention of an acoustic chair, of which an engraving appears on our front page, and which is thus described in his "Treatise on the Ear."+

"The acoustic chair is intended for the benefit and use of the incurable deaf. A somewhat similar chair was constructed in 1706 by M. Duguet, who likewise invented some 'acoustic tubes. But one of the great advantages possessed by my chair over Lis consists in this, that the person sitting in it hears at the opposite side from that at which he is addressed; thus avoiding the unpleasant and injurious practice of the speaker coming so close as to render his breath offensive, and, at the same time, detrimental to the organ of hearing, by causing a relaxation of the membrane of the tympanum. This is an effect commonly produced by the use of short flexible tubes,§ no less than by hearing

+

See Mechanics' Magazine, vol. xxv. p. 69.
"Dick's Christian Philosopher."

A Treatise on the Physiology and Pathology of the Ear. By John Harrison Curtis, Esq., Aurist to his Majesty, &c. Sixth Edition. London: Longman and Co.

Instances are on record in which very baneful and injurious effects have resulted from the practice of speaking into the ear, more especially where the breath of the person is tainted. One case I may mention, which is related by Lord Herbert. Cardinal Wolsey, he tells us, towards the latter part of his life, was in the habit of whispering into the ear of his sovereign, Henry VIII.; and the serious indisposition of the king has been many times attributed to this cause, and certainly not without reason.

trumpets, which latter are as often, perhaps, employed for speaking through, as for the purpose for which they were designed; and it is a certain fact, that many persons, after having used a trumpet for half an hour, are quite deaf, from the action of the breath impelled against the membrana tympani.

"My acoustic chair is se constructed, that, by means of additional tubes, &c., the person seated in it may hear distinctly, while sitting perfectly at ease, whatever transpires in any apartment from which the pipes are carried to the chair; being an improved application of the principles of the speaking-pipes now in general use. This invention is further valuable, and superior to all other similar contrivances, as it requires no trouble or skill in the use of it; and is so perfectly simple in its application, that a child may employ it with as much facility, and as effectually, as an adult. It is, moreover, a very comfortable and elegant piece of furniture.

"This chair is of the size of a large library one, and has a high back, to which are affixed two barrels for sound, so constructed as not to appear unsightly, and at the extremity of each barrel is a perforated plate, which collects sound into a paraboloid vase from any part of the room. The instrument

thus contrived gathers sound, and impresses it more sensibly by giving to it a small quantity of air. The convex end of the vase serves to reflect the voice, and renders it more distinct. Further, the air enclosed in the tube being also excited by the voice, communicates its action to the ear, which thus receives a stronger impression from the articulated voice, or indeed from any other sound. What first induced me to invent this chair was the fatigue I sometimes experienced in talking to deaf persons.

"By means of sufficient tubes, this chair might be made to convey intelligence from St. James's to the Houses of Lords and Commons, and even from London to the King at Windsor. Marvellous as this may seem, the idea is not a novelty; it is but another confirmation of the saying of Solomon, that there is nothing new under the sun. M. Itard, in his excellent work on the ear, tells us that Aristotle (who was physician to Alexander the Great) invented a trumpet for his master, which was capable of conveying orders to his generals at the distance of 100 stadia, equal to rather more than 12 miles. And I may remark, bearing in mind, too,

"This is mentioned in a MS. found some time since in the Vatican, entitled Secreta Aristotelis ad Alexandrum Magnum, and is stated to have been five cubits in diameter. Sir John Morland's speaking-trumpet only conveyed sound on the open sea for a distance of two miles, even when the wind was favourable.

that both Alèmeon and Hippocrates are said to have invented ear-trumpets, that the ancients do not seem to have been so ignorant of acoustics as some in our day have represented them."

In the engraving, A is the acoustic barrel, B the acoustic conductor, C the tube to be applied to the ear, and D the tunnel by which the sound is to be conveyed. This chair is only shown adapted for hearing; to convey sound from it to a distance, there should be another conductor, and a mouth-piece to speak through.

We understand that Mr. Curtis has at present before the Lords of the Treasury a plan for conveying messages from one Government-office to another, upon the same principle as the chair; as, for instance, between the various official departments in Whitehall, from the Horse Guards to the Mansion House, &c.

In the work which we before quoted (the "Christian Philosopher,") are some very interesting remarks upon the subject, which we subjoin :

"Some experiments have lately (1828) been made by M. Biot,' on the transmission of sound through solid bodies, and through air, in very long tubes.' These experiments were made by means of long cylindrical pipes, which were constructed for conduits and aqueducts, to embellish the city of Paris. The pipes by which he wished to ascertain at what distance sounds are audible, were 1,039 yards, or nearly five furlongs, in length. M. Biot was stationed at the one end of this series of pipes, and Mr. Martin, a gentleman who assisted in the experiments, at the other. They heard the lowest voice, so as perfectly to distinguish the words, and to keep up a conversation on all the subjects of the experiments. I wished,' says M. Biot, to determine the point at which the human voice ceases to be audible, but could not accomplish it: words spoken as low as when we whisper a secret in another's ear, were heard and understood; so that not to be heard, there was but one resource, that of not speaking at all. This mode of conversing with an invisible neighbour, is so singular, that we cannot help being surprised, even though acquainted with the cause. Between a question and answer, the interval was not greater than was necessary for the transmission of sound. For Mr. Martin and me, at the distance of 1,039 yards, this time, was about 5 seconds.' Reports of a pistol fired at one end, occasioned a considerable explosion at the other. The air was driven out of the pipe with sufficient force to give

the hand a smart blow, to drive light sustances out of it to the distance of half a yard, and to extinguish a candle, though it was 1,039 yards distant from the place where the pistol was fired. A detailed account of these experiments may be seen in Nicholson's Phil. Jour., for October, 1811. Don Gautier, the inventor of the Telegraph, suggested also the method of conveying articulate sounds to a great distance. He proposed to build horizontal tunnels, widening at the remoter extremity, and found that at the distance of 400 fathoms, or nearly half a mile, the ticking of a watch could be heard far better than close to the ear. He calculated that a series of such tunnels would convey a message 900 miles in an hour.

"From the experiments now stated, it appears highly probable, that sounds may be conveyed to an indefinite distance. If one man can converse with another at the distance of nearly three quarters of a mile, by means of the softest whisper, there is every reason to believe, that they could hold a conversation at the distance of thirty or forty miles, provided the requisite tunnels were constructed for this purpose. The latter case does not appear more wonderful than the former. Were this point fully determined, by experiments conducted on a more extensive scale, a variety of interesting effects would follow, from a practical application of the results. A person at one end of a large city, at an appointed hour, might communicate a message, or hold a conversation with his friend, at another; friends in neighbouring, or even in distant towns, might hold an occasional correspondence by articulate sounds, and recognise each other's identity by their tones of voice. In the case of sickness, accident, or death, intelligence could thus be instantly communicated, and the tender sympathy of friends immediately exchanged. A clergyman sitting in his own room in Edinburgh, were it at any time expedient, might address a congregation in Musselburgh or Dalkeith, or even in Glasgow. He might preach the same sermon to his own church, and the next hour to an assembly at forty miles distant. And surely there could be no valid objection to trying the effect of an invisible preacher on a Christian audience. On similar principles, an apparatus might be constructed for augmenting the strength of the human voice, so as to make it extend its force to an assembled multitude composed of fifty or a hundred thousand individuals. In short, intelligence respecting every important discovery, occurrence, and event, might thus be communicated, through the extent of a whole kingdom, within the space of an hour after it had taken place."

Mr. Curtis has also invented various