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iron, with less difficulty; I conceive it to be a very difficult thing to make & wrought iron boiler so strong as we can have it cast; we have some of our boilers made two inches thick; and to make a wrought iron boiler equally strong as that, would be very difficult to be accomplished by work

men.

Supposing the only object to be safety to the lives or limbs of the persons who should be surrounding the engine, would you in that case prefer having the boiler of a high pressure engine of wrought or of cast iron? -I would have cast iron, because it can certainly be made stronger than wrought iron for the same expence."

Mr Thomas Lean." Have you any choice, in point of safety only, between a boiler constructed of cast iron or of wrought iron ?-Were I to have a boiler where I wished to have the greatest strength, I would certainly have it made of cast iron; I have not one doubt that a cast iron boiler can be made much stronger than it is possible to make a wrought iron one; in fact, the explosions that we have had in Cornwall have all been in wrought iron boilers, but I never had one in cast iron boilers, nor have we had an accident from high pressure steam; all the accidents have been from low pressure steam in Corn

wall."

Having thus extracted the substance of the examination, so far as relates to these two leading questions, I shall now beg leave to make a few observations.

The Committee report, that the persons examined "generally agree, though with some exceptions, that those called high pressure engines may be safely used, with the precaution of well constructed boilers, and properly adapted safety valves." Now, I cannot exactly agree with the Committee in this general inference. A great majority, I think fully twothirds, are decidedly against the high pressure engines. It is farther to be observed, that these persons include almost all who have had any observation of, or concern with steam-boats; while the advocates of high pressure are almost all persons connected with the application of steam to machinery used in manufactures. They are, indeed, almost exclusively the persons

VOL. I.

appears

who construct engines for the use of the Cornish miners. When employed for that purpose, there to be a great saving, in point of economy, in the use of high pressure engines. Without, however, supposing any bias from this cause, the two cases are different, and different rules may apply to them. It would seem, by the testimony of those concerned in steamboats, that the low pressure boilers burst almost as often as the high pressure; but, in bursting, they do no injury; the fragments never explode. The only danger is from the scalding of the steam; but this seems never to have been experienced in boats, probably from the covered state of the engine; it occurred only in mines or manufactures, where the workmen were exposed to the steam. It appears to follow, therefore, that his Majesty's subjects may travel in boats using low pressure engines, with perfect safety to life and limb. Moreover, these boats seem, in all common cases, capable of sailing with every degree of rapidity which can be wished for. The steamboats on the Clyde go, I believe, at the rate of seven or eight miles an hour, which is as rapid sailing as any There one could desire or choose. seems no motive, therefore, for encountering the hazard of explosion, which probably can never be entirely prevented in high pressure engines, I am not prepared to say, that the Legislature ought absolutely to prohibit the use of boats with such engines; because I share the feeling of the Committee, that as little restraint as possible ought to be placed on the natural course of human industry. I only conceive, that, unless in very pe culiar and special cases, the use of high pressure engines in boats can serve no purpose, and ought to be entirely discouraged. The Committee also appear to me to be departing from their own principle, when they load all steamboats indiscriminately with troublesome and expensive regulations, which seem to be necessary or applicable only in the case of those using high pressure engines. If the bursting of low pressure engines never produces any damage, why require, before every voyage, an examination by an engineer, whose presence it may be difficult and expensive to procure?why also demand, that the boiler should be made capable of bearing six

D

times the pressure which it is intend ́ed to sustain ?

The Committee also report, that a great majority of opinions lean to boilers of wrought iron or metal, in preference to cast iron;" and they therefore recommend as a regulation, "that all boilers belonging to the engines by which such vessels shall be worked, should be composed of wrought iron or copper." Generally speaking, the same persons who recommend low pressure engines, recommend wrought iron; and those who advise high pressure engines, advise cast iron. We do not exactly know why the Committee has adhered to the former in the one case, and to the latter in the other. The general result seems to be, that cast iron boilers may be made stronger than wrought iron, and consequently less liable to explode; but, when they do explode, they occasion more damage. On these grounds, the preference between the two appears somewhat of a dubious point. But, at all events, as the only object in the use of wrought iron is to diminish the injury produced by an explosion, I can see no possible motive for compelling the adoption of it in low pressure engines, which never explode. The hardship of such a regulation would also be very considerable, as it would render useless all the low pressure engines at present composed of cast iron, and oblige the proprietors to incur the expence of a new machine. Upon the whole, the result of the evidence here collected appears to be, that there is no ground for giving any encouragement to the use of high pressure engines in steam-boats. But, if any proprietors choose to set such on foot, it is very proper that they should be made liable to the regulations proposed by the Committee. To impose, however, the same regulations upon all steam-boats, appears to be both unnecessary and vexatious.

MISCELLANEOUS OBSERVATIONS ON SOME FACTS IN NATURAL HISTORY.

MR EDITOR,

THE following observations, though unconnected by any other relation than that of having been made in the same situation, may probably afford an amusement to such of your readers as delight to wander, at this fine season, by the sea side, and to remark the

varieties of organized life, or the diversified appearances of the laws of nature, which are there presented. The facts which I have to notice, are not, besides, very generally known, and seem, on both these accounts, to be deserving of a place in your useful miscellany.

1. My first observation relates to that species of marine animal which is known to naturalists by the name of Medusa Capillata. It is a frequent inhabitant of most of the shores of this island, and may easily be distinguished from the other species of the same animal, by the remarkable transparency of its whole mass; and more particularly by some beautiful spots of bright purple, which are placed near the centre of its disk. I ought, perhaps, to remark, for the sake of some of your readers, that the class of animals, of which that alluded to in the following observation is a species, is commonly known in this country by the name of the sea-blubber, and is remarkable for several striking properties, which characterize some of its species, such as that of occasioning a feeling of irritation in the skin when touched, and of being phosphorescent in the dark. To a common observer, all the varieties of this animal appear to be merely masses of a transparent jelly, scarcely worthy of being ranked among the class of animals, and apparently driven, without the power of directing their course, by the varying direction of the winds or the waves. If, however, on a fine day, when the sea is calm, and when one of the species to which I now allude is swimming near the shore, an attentive eye be kept upon its movements, within a yard or two of the place of the animal, the following very beautiful and amusing appearance will be observed. As the animal moves forward, it is constantly employed in forming its disk into a greater or less degree of convexity, while at every such change in the form of its mass, a fringe of most beautiful and apparently silky filaments, all around the circumference of the disk, is protruded into the water, and again withdrawn into the body of the animal, as it resumes its ordinary and more flattened appearance. These filaments proceed from the circumference of a circular space, which is placed near the centre of the animal, and may be distinctly seen

passing from thence, in the form of rays, to the extremity of the disk. The progress of this animal is there fore performed, as the reader will understand from the foregoing remarks, by a species of spinning; and the kind of organization by which this is effected, has always appeared to myself to be one of the most pleasing instances of the wisdom of nature with which I am acquainted, and adapted most happily to illustrate the remark, that some of the finest specimens of what is exquisite in structure, may be discovered in animals of the very lowest order.

I am not certain whether any other of the species of this class possess the same organ to which I have now alluded. Indeed I think we have reason to believe, that most of the species possess a power of locomotion, though not apparently of so fine a construction, yet certainly capable of accelerating their progress to a much greater degree. I remember, indeed, to have been once remarkably struck with this, fact, while bathing with a companion in one of those arms of the sea which intersect the western shores of Argyllshire. We had been in use, during the greater part of the summer, to bathe in the same spot. One day, however, we were astonished on advancing farther into the water, to perceive myriads of the Medusa in rapid progress from the head of the loch, apparently towards the open sea. They continued to float by us in countless numbers, during the whole of the time we continued in the water; and though I was aware of the effect which some of the species are said to produce upon the skin when handled, we yet ventured, in youthful wantonness, and, I dare say, to the no small annoyance of the "emigrants," to pelt one another with them for a very considerable time, without afterwards experiencing any disagreeable sensations. Next day, no appearance of the Medusa could be seen; and I inferred at the time, that the animal was accustomed, at certain seasons, to make long and rapid migrations, probably from the quiet and shelter of the inland bays, towards the open sea. Those who are acquainted with the late voyage of Humboldt across the Atlantic, will indeed recollect, that one part of that vast sea is completely covered by many species of this animal, for the

existence of which, in that situation, the naturalist was very much puzzled to account. A collection of observations like the foregoing, would probably enable us to solve this difficulty.

I have only further to remark on this article, that, as the substance of the Medusa is gelatinous, and as this matter is soluble in common water, any person may procure the filaments I before noticed, by placing one of the animals possessing them in a bason of river water during forty-eight hours. At the end of that time, the substance of the animal will be found to have become entirely dissolved, and the filaments will be obtained floating on the surface.

2. My next observation relates to a remarkable appearance produced by the refraction of the rays of light. If an observer is seated on a ledge of rock which has a gentle declivity towards the sea, and it the tide is in such a state that the wave, after having advanced upon the rock, rests precisely at its margin when the water is at its utmost retreat, the following amusing appearance will be remarked. As the wave alternately advances and retires, that part of the rock which is subject to the inundation, will appear to be alternately lifted and depressed with something resembling "a living motion." The solid stone, in short, will appear as if transformed into something either endued with spontaneous activity, or at least so light and moveable in its texture, as to be agitated with the same facility, and very much in the same way as the floating fuci which may happen to be attached to it.

There are few of your readers, I dare say, of those at least who shall actually observe the appearance, who will find any difficulty in assigning the cause of it. Every person knows, that if a shilling be put into a bason, so as to be covered from the view of an observer by its margin, and if water be then poured into the bason, the piece of money is seen gradually to rise in the water, so as to become completely visible to the eye of the spectator. It is evidently in precisely the same way that the alternate appearance of elevation and depression in the margin of the rock is produced. When the advancing wave gradually makes its way up the sloping surface, that part of the stone

which is covered by the water, of course, appears to be affected with a gradual elevation; as the wave retires, the rock necessarily sinks to its proper level; and if the ebb of the wave does not go beyond the boundary of the rock, the appearance of motion is of course uninterrupted; and when it has once attracted the notice of the observer, will be found to present a phenomenon which it is both amusing and instructive to contemplate.

3. I have now to direct the attention of your readers to some particulars respecting the production and diffusion of fogs. It has been stated as being now decisively proved, that fogs are not to be regarded merely as vapour suspended in the air by the simple circumstance of the inferior specific gravity of their particles, but as moisture so combined with electricity, as to assume that inferior gravity by which its suspension is affected; and, as a proof of this, it is said, that, on one occasion, a fog having been carried very near a tree, the electricity of the fog was attracted by the tree, and the moisture thus deprived of its electricity was so immediately converted into snow, as actually to tear up, by its overwhelming impulse, the roots of the tree upon whose branches it had rested. Now, although the fact, when thus stated, certainly possesses no slight

resemblance to some of those which the renowned Munchausen observed in the course of his journeyings, I have yet long been convinced that the theory which it supposes is perfectly correct. Indeed, considering how far our knowledge of the properties of electricity has been extended, and how certainly we are now informed of its universal diffusion, it is not a little astonishing that philosophers should persist, with such obstinacy, in excluding it from their explanations of those ordinary appearances, with which it cannot be doubted that it has the most intimate connection. Who, for instance, can doubt that snow, and rain, and dew, in all their varieties, are not merely dependent, according to the prevailing theory, upon the meeting and intermixture of currents of air of different temperatures,-but, far more, upon changes taking place in that active fluid, which seems to pervade and communicate their most important properties to every thing upon and around this globe. That

the production of mist is chiefly de pendent upon the agency of this fluid, I am satisfied, among other considerations, from a fact which I have fre quently noticed upon the sandy shores of the Firth of Forth. When the air is in that state which is productive of mist, that is, when an east or northeast wind has been blowing for some time, I have frequently remarked, that the water which was left upon the sands of the beach, and in every basin and pool which was near the shore, is carried off by evaporation, with a celerity and power which gives to the whole coast the appearance of a vast smoking furnace. And that this is not merely the effect of the temperature of the air at the time, must be evident from this consideration, that, on many of our most splendid and sultry days, when the wind happens to blow from any of the south or west points, no trace of evaporation can be perceived, and the atmosphere is indeed remarkable for a very peculiar degree of transparency.

An east wind, in this climate, therefore, I apprehend, is to be considered as connected with important changes in the electrical state of the atmosphere, as might indeed have been long ago suspected from the known increase of pressure in this fluid when the wind blows from any of the eastern points. These electrical changes, which probably take place at the same time in the atmosphere and in the earth, appear to be peculiarly favourable to the elevation and suspension of vapour; and hence it happens, that, when the wind blows from the east,

we

are immediately plunged in a cloud of haze or fog, while those genial breezes, which have traversed the Atlantic, and which might have been expected to come to us with wings profusely bedewed with the moisture of their way, pour only around us that beautiful transparency, through which all the hues of nature are seen to advantage.

4. I have one further remark to make. It often happens, in very calm weather, that the sea has the appearance of being very beautifully varied, from portions of its surface being gently agitated, while other portions are in a state of perfect repose; and these alternations are commonly so gracefully disposed, as rather to resemble the effect of some moving body

you in the attainment of this object,
so far as my ability may extend, I am,
Mr Editor, yours very respectfully,
P.

ACCOUNT OF A REMARKABLE AU-
DIENCE OF A POLISH AMBASSADOR
AT THE COURT OF QUEEN ELIZA-
BETH IN 1597.

THE arrival in 1597 of an ambas

*

which had passed in a winding direction over its surface, than of any cause existing in nature itself. Nothing is more common, indeed, than to hear this appearance ascribed to a variety of causes,-to the oily matter deposited by vessels which had sailed in the direction of the more placid portions, to something in the bottom of the sea which rendered the surface more easily agitated in some parts than in others,-to the influence of clouds exerting a composing energy on those tracts of water which lie beneath them, or to the effect of promontories and other partial irregularities in interrupting the natural direction of the wind. The simple account, however, of these appearances, seems to be, that, besides those greater and more extensive agitations to which the atmosphere around us is constantly liable, its lowest stratum is also occasionally subject, especially where it is in contact with the surface of the sea, to a tremulous agitation of a far less perceptible character; which seems to originate in causes somewhat different from that by which wind is produced; and the existence of which could only be discovered by its effect upon a surface so easily agitated as that which a very placid sea presents. It is to this slight tremulous agitation in the lower surface of the air, a motion, I may remark, which is probably not very easily propagated, which seems, as I have already said, to depend upon causes of a peculiar nature, and not necessarily to be carried forward like wind, in a continued stream, that I am disposed to attribute those variations of the surface, by which even the calmest sea is commonly marked; and I am persuaded, that any person who will take the trouble of remarking the manner in which these agitated and calmer portions of the water are gradually varied and intermingled with each other, will readily acquiesce in this solution of the phe-ceived of the beauty and elegance of his

nomenon.

Whatever, Sir, may be the truth of these explanations, I apprehend, how ever, that your miscellany can seldom be better employed than in giving currency to such views of the appearances of Nature as may lead your readers to a more intelligent observation of the beauteous order which prevails around us; and, with assurances of my being always ready to assist

sador from Sigismund the Third, King of Poland, at the Court of Eliza beth, is mentioned by all the historians of her reign. This ambassador, whose name was Paul Dzialenski, was sent to complain of some interruption of the Polish commerce by the English cruizers; a measure to which, according to Carte, his master was instigated by certain Jesuits at his Court in the interest of the King of Spain. Elizabeth granted him a public audience, at which he addressed her in a harangue of uncommon boldness and vehemence, to which she immediately made a suitable reply in Latin, in which tongue the Pole had spoken. The substance of both their speeches is given in Camden's Annals, and in Carte's History; but we have procured an extract from the Burghley Manuscripts, preserved in the British Museum, of a letter from Sir Robert Cecil to the Earl of Essex, which, as it contains much more minute details of the circumstances attending this remarkable audience than are to be found in these histories, cannot fail, we should think, to prove interesting to our readers.

The letter is not a little curious in several respects. Elizabeth's partiality for handsome men is well known to all who are acquainted with her history and character; and it appears from this letter, that she was induced to grant the Polish ambassador a public and splendid audience, from the very favourable accounts she had re

person and manners. She seems to have been prepared to hear an address from him, couched in those romantic terms of love and admiration in which she was sometimes accosted by her courtiers; who, when they wished to ingratiate themselves, always contrived to mingle

* Carte's History of England, Vol. III. p. 665.

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