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No. 242. —VOL.· V.

LETTERS

ON THE REVOLUTIONS OF THE GLOBE.

BY M. ALEX. B.

La legère couche de vie, qui fleurit à la surface du globe, ne wwere que des ruines.-Paris: printed, 1824.

TUESDAY, FEBRUARY 15, 1825.

Translated expressly for the Kaleidoscope from a recent French work. mile.

LETTER VL-CONTINUATION OF VOLCANOES. NEW ISLAND, WHICH ROSE FROM THE SEA NEAR TERCERA, IN 1720.

[Account given by Mr. Th. Forster.]

John Robinson, Captain of a small New England snow, a rived at Tercera, on the 10th of December, 1720. He a fire issuing from the sea, near that island. The goernor prevailed on him to approach it with his vessel, ad sent on board sixteen sailors, and two priests. The Lllowing is his own relation of what he saw :

ples, and more than four distant from the sea. The foot
of the mountain borders the coast, and its inclination is
so gradual as far as the first plain, that it may easily be
ascended on horseback up to that point. This plain is
nearly circular, and is about six miles in diameter; its
perpendicular height above the level of the sea is half a
Thence rises another mountain, called, in the
country, Monte-Vecchio, of an irregular shape, and about
four hundred paces in perpendicular height. Its summit
is hardly two miles in circumference, and was, before the
year 1631, hollowed out in the form of a basin; it was
surrounded by old oaks, and enormous chesnut-trees,
whose fruits afforded nourishment to a large number of
cattle; there was, at the bottom of it, a cavern, into which
it was possible to descend more than two hundred paces,
although with some difficulty. This aperture was consi-
dered as the ancient crater, which, during a long time,
had ejected a prodigious quantity of bituminous matter,
and laid waste a considerable part of the surrounding

On Sunday, the 18th of December, we set sail at mid-country. ight, and stood to the south-east of Angra; the follow

ig day, at two o'clock in the afternoon, we approached island, entirely composed of fire and smoke. We consued our course towards it, until the ashes fell upon our ek, like hail or snow, which they continued to do all ight. We then stood out to sea; noises like thunder, or eals of cannon, proceeded from the fire and smoke. At sy-break we again sailed towards the island, and at noon ere sufficiently within view of it to observe it, being only o leagues to the south of it. We sailed round it, and proached so near, that we narrowly escaped being inred by the fire and matter ejected from it. We were apprehensive lest we should be thrown upon the ast; but a south-east wind, which rose whilst we were at prayers, delivered us from danger. The breeze was companied by a slight shower, which caused a great al of dust to fall upon our deck. We took advantage the wind to return to Tercera.

The governor informed us that the fire had exploded on e 20th of November, 1720, in the night-time, and that se frightful noise which it occasioned caused the earth to emble, and overturned several houses in the town of ngra, and its neighbourhood, to the great consternation the inhabitants. Prodigious quantities of pumice stones ere found at the distance of several leagues round the land, and fishes, half broiled, were seen floating on the ea, with flocks of birds, gathered round them, to feed apon them. This new island is nearly round, and is bout two leagues in diameter. Its latitude is 38 degrees 9 minutes, and its longitude 26 degrees 33 minutes (meidian of London.)

A person of my acquaintance, passing from Cadiz to London towards the end of April 1721, told me that he jad found the sea covered with pumice stones, from Cape Finister nearly to the entrance of the Channel; he gave me some, which he had gathered.

ERUPTION OF MOUNT VESUVIUS IN 1737. Particulars given by the Prince Cassano, a member of the Royal Society in London; extracted from the Philosophical Transactions.)

Mount Vesuvius is about seven miles distant from Na

PRICE 3o4

twenty-nine years, it again began to burn in 1660, and entirely filled with lava the immense cavity formed in 1631, within which, after several smaller eruptions, a new mountain arose in 1685.

In 1707, all the inhabitants of the country around, and of the city of Naples, were thrown into alarm by frequent explosions and concussions, and by the fire which again burst forth from the summit of the mountain. An enormous quantity of ashes, violently ejected from the crater, filled all the atmosphere, and darkened the sun, during a whole day. Fortunately, these frightful appearances were followed by no fatal effects, and the mountain again became tranquil.

In 1724 the quantity of ashes and stones thrown from the mountain was so great, that it filled all the space between the old and the new mountain.

though inconsiderable, compared with the last, gave rise In 1730 there was a new eruption of Vesuvius, which, to much apprehension.

On the 19th, the summit of the mountain was involved in thick black clouds, and fire was seen to issue from it. on the same day, noises, like the roaring of thunder, were heard to proceed from it, which continued to become more frequent towards evening, and in the course of the night. The mountain then discharged a very thick smoke, intermixed with ashes and stones, and the adjacent country was agitated by some slight concussions.

The eruptions which have taken place before the pre-tain was never tranquil: sometimes it ejected smoke, at During the month of May of this year, 173, the mounsent time, may be divided into ancient and modern. Be- others, burning stones, which fell upon its surface: From rosus, Polybius, Strabo, Diodorus, and Vitruvius, have the 16th to the 19th, hollow, subterranean sounds were mentioned some of the first. Vesuvius, under the reign is of Trajan, became famous by the death of Pliny: there continually heard. no doubt that eruptions were less frequent from that memorable period till the year 1139, when, after a consider able eruption, Vesuvius became tranquil, and remained so during nearly five centuries. This long interval of repose effaced the remembrance of former disasters: the inhabitants of the neighbourhood flattered themselves that the inflammable matter was exhausted, and cultivated all the surrounding land, which, by its fertility, became the garden of the country. But, in the course of time, they were deceived in their hopes. In 1631, during six months, continual roarings were heard to proceed from the mountain, and several earthquakes were experienced. In December there was a terrible eruption of fire, which, at first, caused to explode a part of the mountain. Water, cinders, stones, and fire, were afterwards ejected from the crater, and the lava overflowed a space of country, extending nearly to the sea side, of more than seven miles in breadth, and caused to perish above four thousand persons."

The mountain, after this eruption, was much less elevated than before. Having remained undisturbed during

• The reader may judge of the violence of this eruption by the following account, which I have taken from No. 21 of the Philosophical Transactions, for the year 1666. It was communicated by Captain William Badily. The 6th of December, 1631, being at anchor in the gulf of Valo, in the Archipelago, towards six o'clock in the evening, a shower of sand and ashes began to descend upon us, and continued to do so till two o'clock in the morning. The deck was then covered with layer two inches thick; we scraped it away with shovels, the way in which we had, the day before, removed the snow; there was no wind at the time that these ashes fell. A shower of the same description was also poured down upon some vessels, then at ye leagues' distance from us, which were coming from Saint 'ean d'Acre to our port. We compared the ashes that fell in these different places, and they were of the same nature.

a

N. B. This rain of ashes "proceeded from the eruption of
Vesuvius, mentioned above

On Monday the 20th, at nine o'clock in the morning, the mountain experienced so violent an explosion, that the shock was perceptible to the distance of more than twelve miles round. A black smoke, accompanied with eshes, rose suddenly into the air, and assumed the form of several vast undulating globes, which dilated in proportion as they became more distant from the crater. The explosions continued to be very violent and frequent all day, and stones of an enormous size were thrown to the height of e mile, in the midst of clouds of smoke and ashes.

At eight o'clock in the evening, whilst the concussions and dreadful roarings continued, a new chasm was opened in the mountain, upon the first plain, at a mile's distance from the summit, and there issued from it a vast torrent of fire; from that moment, all the southern part of the mountain appeared to be involved in flames. The torrent flowed into the plain below, which is more than a mile long, and nearly four miles broad. Soon afterwards. it extended nearly a mile further, and at four o'clock in the morning reached the extremity of the plain, and the foot of the small elevation on the southern declivity of the mountain. But, as these eminences are composed of steep rocks, the greatest part of the torrent flowed into the spaces between them, traversed two small valleys, and fell, in two streams, into the other plain which forms the base of the mountain. After having been again united here, it divided itself into four branches, one of which stopped in the middle of the road leading to Torre del Greco, at the distance of a mile and a half from that village; the second

flowed into a large valley; the third continued its course and the fourth to a place at a short distance from the new

as far as Torre del Greco, which stands near the sea coast;

crater.

human observation; and I am satisfied that the day will
come when the punishment of death will be generally
deemed an unwarrantable and presumptuous interference
with the prerogative of the Creator.

The consideration of the leading features of human

on the Rock of Ages, whose unerring wisdom is surely a better guide than our own understandings! Expedierer: is it not a distrust of Providence? a paltry subteries in place of truth? a doing of evil that good may come Small indeed must be the faith of those who uphold the doctrine of expediency.

cogn

The torrent, which flowed through the valley, arrived at the space of ground between the church of the Carmel-policy, the institutions or customs of a country, must be If in a school, where many children are gathered tog ites and that of the Souls in Purgatory, at four o'clock in pressed upon us; for what inducement could we have to ther, and they, being under the control of the master, the morning. The matter composing fit had the consist- call in question the propriety of those things which have laws amongst themselves, and go so far as to expel ar ency of melted lead, and its progress was at the rate of been sanctioned by the whole world, backed by the weight master? or can they plead expediency on their behalf offender, do they not trench upon the prerogative of the four miles an hour. This degree of velocity was extraor- of antiquity, and consolidated by the lapse of ages? it A master is supposed to have undoubted rule and dinary, since it was thought surprising, that in the erup- may seem a bold speculation to set aside those circum-zance of all within his school, and never delegates the tion of 1618, the lava had advanced sixty paces in an hour. stances, but it is necessary, and will be advantageous to power of expulsion to the hands or the judgment of bis The torrent, which flowed behind the convent of the seek the naked truth; for truth, ultimately, is always con- pupils. But, oh! how immeasurable is the distance be Carmelites, entered the church, after having set fire to the sistent with the happiness and well-being of society. It He, more than master, seeing all that ever passes amergat tween man and his Creator!-we are less than chilera; small door; it also penetrated through the windows of the will be acknowledged, that in a Christian community, the us, and as no crime can be hidden, so none can escape vestry, and of two other apartments: it burned the win- | foundation of all law ought to be the will of God, as ma- punishment. dows of the refectory; and the glass vessels upon the ta- nifested in the institutions of the gospel. Had Christian bles were reduced to paste, by the violence of the fire. legislators sufficiently considered this, and disregarded the Sixteen days afterwards, the lava was still warm and very miserable doctrine of expediency, laws, and with them, hard; it was, however, found possible to break it. the people, would have been greatly exalted, and different A bit of glass, fixed at the end of a stick, and placed in many respects from what we find them; but what near this matter, was reduced to paste in four minutes; could be expected when the mental darkness in which the under the mass of the torrent, frequent rumblings were world was involved was such, that Christians could not heard, which made the church tremble. There were, upon agree which was that course wherein "the wayfaring man, its surface, several small crevices, through which issued a though a fool, should not err ?" As knowledge, begun in smoke, that diffused an odour like that of sulphur mixed early life by education, and enlarged afterwards by cultiwith sea water, and the stones around were covered withvation and literature, gains a more extended footing, it saline sublimations. Pieces of iron, introduced in these clefts, were drawn out damp; but paper, placed there, seemed to become hard and dry.

At the same time that the new crater was opened, that at the summit emitted a vast quantity of burning matter, which, dividing itself into several torrents and currents, directed its course, partly towards Salvadora, and partly towards Ottajano. Burning stones, involved in clouds of thick smoke, were also ejected from the top of the mountain; this phenomenon was accompanied by frequent peals of thunder, and flashes of lightning.

The eruption of burning matter lasted till the following Tuesday; upon that day it was discontinued, and the thunder and lightning ceased; but a south-west wind began to blow with violence, and transported the ashes in great quantities to the extremites of the kingdom. In some places they were very fine, in others, as coarse as gravel. Showers, not only of ashes, but of pumice stones, and stones of other kinds, were experienced in the neigh

bourhood of Vesuvius.

The fury of the volcano was somewhat appeased on Tuesday evening; on the following Sunday, the flames were hardly visible at the upper crater, and on Monday there was nothing to be seen there but smoke and ashes. It began to rain abundantly on that day, and continued to do so during Tuesday, and several days following. The eruptions have always been succeeded by rains.

The damage occasioned in the neighbourhood by this eruption of fire and ashes is incredible. At Ottajano, situated at four or five miles' distance from Vesuvius, the ground was covered with a layer of ashes, four palms in thickness. All the trees were burnt, the inhabitants were thrown into the utmost terror and consternation, and many houses fell under the weight of ashes and stones.

The Philanthropist.

LETTERS OF A LITERARY DEVOTEE.

No. II.-ON CAPITAL PUNISHMENT. "Vengeance is mine; I will repay, saith the Lord." After a long interval, I again find opportunity to volunteer a few thoughts on this momentous topic. The casual, the slight, but serious communications of individuals, and the agitation in converse, may at length lead to the recognition by governments of a great moral truth, long hidden under the mass of ignorance and prejudice, a truth among the many which time more and more unfolds to

a

I have not attempted to extenuate the deep strocity of murder, nor do I even say that a murderer is serving of an ignominious death; but his offence is two-fold, against God and against society; and while the latest may justly confine and punish with bonds, it is of eternal in portance that that time, wherein his peace with God way be made, should not be shortened by his fellow man. Al ment of death is too awful to be lodged in the bands of that I have laboured to show is this,-that the pati man, and that the extinction of life belongs exclusid Him who gave it.

Scientific Records.

NEWLY-DISCOVERED ISLAND.

New island in the Southern Ocean, from the last an We copy the following account of the discovery of received from New South Wales. The merit of th covery rests with Captain Hunter, of the Donna Cala and from the logbook of that ship we copy the fi interesting account:

At 11, so close in shore, armed and manned the c and our friend the chief, keeping another on beard as and despatched her on shore in charge of the first hostage.

chases the darkness, the superstition, the ignorance, the
prejudices of past ages, progressively away: imbued with
knowledge, the mind comes to the search of hidden truths
with the best of all concomitants-light. This light, we
have reason to believe, is steadily advancing among the
whole human race: in our own government it is exempli-
fied by those liberal views which have lately obtained, and
have given such satisfaction, perhaps, in degree, as an
earnest of better things; nor is it less apparent else- At 11h. 30m. p. m. saw the land bearing S. W. by
July 29.-Fine clear weather, carrying all possible val
where; but this is digressive. Our inquiry is into the distance six miles; up courses and shortened sail
propriety of capital punishment among a Christian people, top-sails, and stood towards it at daylight; fresh brees
and to grapple effectually with the matter, let us suppose the land discovered proved to be an island. At thre
a case, whose bearings shall comprise the question.
p. m. close in under the lee of it, observed a number of f
If, in wandering through some solitary path, I meet with all possible despatch: bore down and intercepted
ing canoes to leeward, which were flying for the sh
man who is a robber and a murderer, no matter whether he of them; with a great deal of persuasion got one of t
be the most ignorant and brutal character, or whether he people to come on board, when I presented him with a
moves in a more respectable rank; immaterial is it whe-hatchet and a piece of white cloth, which pleased
ther his motives be revengeful or mercenary, my death much, as he showed it to all the canoes about the ship,
is inevitable, unless, in this dilemma, by anticipating his chief came on board, and on my making signs the
after that we did not want for visitors. About this tit
design, I inflict on him the fate he had intended for me. wanted refreshments, he sent all the canoes on shore,
Now, I confess, I dare not preserve life by this alter-staid himself on board with a few others.
native. There are many, no doubt, who would urge, that
self-preservation is the first law of nature; that necessity
has no law, and so forth; good reasons, so far as they go,
but not sufficient. Be it remembered, that among Chris-
tians, the preservation of the soul is a superior object to
the preservation of self, and the disobedience of one does
not suspend the obligation of another to the Divine com-
mand-" Thou shalt not kill." He who looketh on all
with an equal eye, hath taught that it is better to suffer than
to inflict evil; and surely the untimely death of a mur-
derer must be a sore evil. Does the reader believe, then,
that any thing could justify him in taking the life of a
fellow-creature, short of a Divine command or permis-pical fruits of all kinds.
sion? which he will find difficult to produce from the
words or tenor of the gospel: if not, it must follow, that
in our religion there is no such thing as justifiable homi-
cide, nor any authority from the great Author of life for
capital punishment. It will not avail to say that the exe-
cution of one criminal may possibly save the life not only
but the lives of an indefinite number of innocent
persons, which, if ever it does, though very doubtful, does
not touch on the propriety of the thing itself; other means,
less sanguinary, might be quite as efficacious: nor do I
see how the present penal system can be prevented from
grounding on the doctrine of expedienc; Oh, the shift-
ing sands of expediency! how abhorent to the unchange-
able spirit of truth! how alien to nat humble dependence

of one,

* See Paley.

At one, p. m. the canoes returned from shore, number of thirty, laden with hogs, yams, plantains, and traded with the greatest honesty for iron hoops, often got their canoes overturned, but it never inom &c. They seemed to be very expert swimmers, the them, for they soon put them to rights. They s the colour of Malays, but have more of the features. The canoes are very handsome, not m of Ceylon, and ornamented with shells.

At four p. m. the cutter returned from the shore, b on board twelve hogs, a great quantity of yams and

The following is the chief officer's report of the of Onacuse, or Hunter's Island:

At one p. m. got close in shore; the native desire of people assembled on a bluff point of land. The not to pull in shore, when we observed a great conc being pretty high, we landed opposite the people. The native in the cutter pointed out the King (Fuuafoa) the monarch, with his attendants, came round, and s himself close to the boat, when the native desired walk towards the King. I thought it best to go unar as it would make them have more confidence in us of them were armed with clubs, with short round b and some with spears, from twenty-four to forty feet and a few were much longer. A great many won numbers of whom carried two spears, were present was desired to sit down close to the King, and after ma my obeisance, presented him with a white shirt, purti on him. I likewise gave the same to his brother;

MECHANICAL PARADOX.

TO THE EDITOR.

of the rail, QML a line

seemed highly pleased, and in return made a present of a si l'on vient à augmenter l'une de ces deux forces, Imaginons
hog, a basket of yams, and bananahs and cocoa nuts. qu'on augmente la puissance; le mouvement naitra peu à
After sitting some time, I made the King a present of a peu, et s'accélérera par degrés, Cette accélération durera
looking-glass, which seemed to surprise them greatly: tant que la puissance sera plus forte que la resistance. Mais
SIR, I now
it went from the King to the Queen, and from her all si, par quelque cause que ce soit, la puissance vient à dimi-
round, every one taking a look at it, and then touching nuer, ou que la puissance, demeurant la même, la resistance promise of giving a more
proceed to redeem my
the crown of their heads with it; and the same ceremony vienne à augmenter, l'accélération diminuera; et lorsque la
general demonstration
was performed with every little present made them. The puissance et la resistance auront les valeurs simplement
of the principles by which
King took a shell from his neck, and gave it me; I then requises pour l'équilibre, le mouvement deviendra uniforme;
locomotive engines are
made signs if there was any water to be had; they said il demeurera tel en vertu de l'inertie de la matière; la puis-
governed. Let C be the
Howtow, and pointed among the hills. I expressed a
sance ne fera plus à chaque instant que combattre les coups
common centre of the
wish to go and see the watering-place; the King got up sans cesse renaissans de la resistance."-See Considerations
wheel and crank, CQ the
and desired me to follow, with our friend the native. I mathematiques et physiques sur les Machines en mouvement.
crank, CF a radius of
took the carpenter and four men armed, in case of acci- The following is from Art. 907, Maclaurin's Fluxions:-
lent. The King had gone by a shorter route over the
"In any engine, the proportion of the power to the weight,
the wheel, FL a portion
ill; however, I soon found it was not the watering-place when the balance each other, is found by supposing the en-perpendicular to the rail
hey were taking us to, for we found ourselves on the gine to move, and reducing their velocities to the respective then QCF may be con-
each, not far from the boat, in a kind or cone, with a directions in which they act; for the inverse ratio of those sidered as a lever kept at
mooth beach, where we saw his Majesty seated with all velocities is that of the power to the weight, according to rest by three forces, viz.
is attendants, and I was requested to sit down opposite the general principles of mechanics. But it is of use to de-
him on the ground, which I accordingly did. The beach termine likewise the proportion they ought to bear to each
was marked out into apartments by rows of stones. The other, that, when the power prevails, and the engine is in
women were ordered on one side, but only for a short motion, it may produce the greatest effect in a given time.
time, when they all crowded round us, and were particu-When the power prevails, the weight moves at first with an
lar in looking at our shoes and buttons, but were very invariable, its action upon the weight decreases, while the
accelerated motion; and, when the velocity of the power is
ivil Shortly after the King's mother came down, an
lderly woman, about fifty, the King himself seemed velocity of the weight increases.
Thus the action of a
hout thirty, his Queen about twenty, stout and good from the excess of the velocity of the fluid above the velocity
stream of water or air upon a wheel is to be estimated
oking, and was the only one that had part of her bosom of the part of the engine which its strikes, or their relative
vered. She was a very fine figure, her teeth perfectly velocity only. The motion of the engine ceases to be acce-
en, and very clean. All the women and men had their lerated when the relative velocity is so fur diminished, that
tle fingers cut off by the second joint on the left hand, the action of the power becomes equal to the resistance of
ad the women had their cheek bones perforated, and the the engine, arising from the gravity of the matter that is
god smeared round about an inch. Some of them were elevated by it, and from friction; for when these balance
tooed with a red colour, especially in their arms, mostly each other, the engine proceeds with the uniform motion
circles about an inch round; they were uncommonly it has acquired."
il, and did not seem at all bashful. The signal being
de from the ship for us, I expressed a wish to go on
rd, and his Majesty expressed a wish to golalso, which,
e would not take canoes to bring him back, I declined.
taram and an ewe with the King, for the benefit of
are navigators, and made signs to the natives not to kill
The women were all naked, excepting a small
ering round the body; and the men mostly wore a kind
mat round their bodies, with leaves of trees woven into
, like a Highlander's kilt. The island was entirely
Eposed of lava, in some places almost a metal. It lies
the lat. of 15. 31. S. and long. 176. 11. E. by sun and
on, brought up by chronometer for four days previous.

E

MECHANICAL PARADOX.

TO THE EDITOR.

prehensible by me; his reasoning is a little too fine. My
What 4. B. T. has advanced about the crank is not com-
opinion is, that the theorems and tables, in Mr. Silvester's
report, are TRUE; that they are founded on scientific princi-
ples; and that they will ultimately be found to agree with
experiment, which is the true test of every theory, that ever
has, or ever will be, advanced.-Yours, very respectfully,

TO THE EDITOR.

A B C.

SIR. Your correspondent, C. C. E. has accounted for the origin of the singular mistakes, into which the author of the report has fallen, in a manner, which, however specious it may be, altogether fails to remove them. A stronger instance could hardly be produced of the truth of the observation, that it is unwise even in the most skilful mathematician riment and analogy. The consideration, that the results are to rely wholly upon calculations without a reference to expetotally repugnant to the known laws of mechanics, ought to have induced a suspicion that the reasoning was incorrect. The notion of the sum of the sines appears to have been borrowed from the theory of the overshot water-wheel, which is in no way applicable to the crank; the power is there equally and constantly diffused over the semi-circumference of the wheel; whereas in the steam-engine, the expenditure of power is in proportion to the verse sine of the are described by the crank. The manner in which the lever is supposed to act is equally erroneous, though the true explanation is not quite obvious, and will require some illustration.

The demonstration formerly given was adopted on account

by the pressure of the steam acting in the direction Q M L, friction of the rail at F; hence the lever C F L may be subthe power of traction acting in the direction C M, and the stituted for it; and, since the forces are in equilibrium, CF is to F L as the pressure to the power of traction. The same tuting the lever M C F for QC F; in which case, the power proportion may be obtained in another manner, by substiat Q will be to its effect upon the rail at F round as C F to by the friction on the rail, the power of traction will be equal CM; but, since the carriage is entirely drawn or impelled to the force exerted on the rail. A third mode of considering drawn by a rope wound round the wheel, when it is evident the question is, to suppose C fixed, and the weight to be that the forces are in the proportion above determined; but, since action and re-action are equal, and in opposite directions, it must be the same thing whether C or F be fixed. Now, CM and F L are equal to the sine of A a. Let V-the velocity, S-the space described, c=3,14159; then CQ-a, CF b, P=the power of the piston, R=the resistance, x=A C Q, W=the weight of the engine and waggons, the power of traction P. a. sin. x. the moving force P. a. sin x and, since P and R are without inertia, the accelerating forceP. a. sin x bw

b

b -R

R
W

also the fluxion of the space described-bx flux.; but the fuxion of V V the force into the fluxion of the space

P. a. sin x. x fl
W

W

Rbxfl
W

P. a. vers. X
W

2nRbc
W

Rbx
W

taking the fluents V V
which taken between the limits of x=0 and x2 ne, be-
If there be another piston, with a crank acting at right angles
comes V V4 Pa
to the former, its force-P. cos x, the fluent of which, be
tween the same limits, will be of the same value; and, there-
fore, if P be now put for the pressure on both pistons, the
expression need not be altered.

sistance and power of traction are equal,
When there is no acceleration of velocity, or when the re-

Your correspondent 4. B. T. still contends the force of steam, on the piston of a steam-engine, is constant force. He has indeed partly agreed that it is but there are extreme cases, he thinks, where that theory In all practical cases, it is true; the limits I pointed my last remarks on this subject. Mechanics (nay even T.) assert that the pressure upon the piston is a certain aber of pounds (as 10, for instance) on a square inch, and this power produces a certain effect. If we be allowed that the force of the steam, acting upon the piston, is valent to a weight of 101b. on a square inch, do we not by the expression that the piston is constantly and uniypressed with a force of 10lb. on a square inch, and that this pressure which moves the machine? If not, what of its simplicity; a method more general and comprehensive, Or, 2 Pa=Rbc and R = emean?-It may be argued, perhaps, that the velocity though not more correct, shall be prepared for the Kaleido episton is not uniform, throughout the whole of a single scope; in the mean time let us inquire what are the true ex-if p be the pressure on the square inch, and d the diameter o e; but the mean force surely remains the same, and, if pressions for the time and velocity. For this purpose let T the pistons, the area of each team be kept at the same temperature, the force pro- the power of traction, as before determined, which, till a cerng each succeeding stroke will be the same. The force tain velocity has been obtained, will be a constant force, that moves a steam-carriage is a constant force; and IW= the weight, Rthe resistance of the inclined plane and no need to argue with so able a philosopher as A. B. T. the friction, V= the velocity, t=the time, and S=the Sonvince him that a constant force, in every case, produces space; then T-R= the moving force, and since both T and Accelerated motion. This is the point on which the disT-R hinges; and when it is once shown that the force which R are without inertia will be the accelerating force; W els a steam-carriage is a constant force, the dispute is at an and the theory advanced by A. B. T. is, in that case, therefore V = 32 T-R T-R S. t and V V = 64 essarily erroneous. Let us suppose, for an instant, that W W force is not constant; and, first, let it decrease uniformly; Ex.-Let W=64,000 lb. T= 500 fb. and R= 400 lb. then this case, as there is a constant opposing force, arising from T-R= 100 lb. V=1-20 t, and VV=1-10 S. If t=3 mition and the weight to be moved, would not the engine nutess, V=9 feet in one second, which is sbout six miles an ve continually slower, and at length stop? On the con- hour, and S=10, V V=810 feet=270 yards in 3 minutes. , if the power increased uniformly, the carriage would rer be made to move uniformly. But the carriage, after a short period, does move uniformly; therefore, the force, moving power, is constant. The following elucidation is Bossut:-"Supposons donc qu'on ait calculé l'equilibre Me machine, c'est-à-dire, la proportion qui doit se trouver tre la puissance et la resistance, pour que la machine, tellement en repos, soit prête à prendre du mouvement,

From the expression, it would appear, that the velocity in-
creases as the time, but then it is derived from the supposition,
that T is a constant force. It has been abundantly shown,
that as soon as the steam is drawn off faster, than the fire can
supply it of the same power, T will be diminished; when it
becomes only 400 tb. or equal to R, the acceleration will cease,
and the motion will become uniform.-Yours, &c.
A. B. T.

pedd
2

Written on reading in the newspapers that a project was on foot for converting Manchester into a seaport, by cutting a canat from the Irish Sea, at the mouth of the Dee, direct to Man

From the papers to-day,

I perceive with dismay,
That our neighbours a project have hit on,
By which it is clear,

That their town, in a year,

Will become the "metropolis" of Britain

These Lords of the shuttle,
By a process most subtle,

A canal mean to cut from the ocean,
And the great Irish Sea

They'll "unite with the DEE,"
But it's Fiddle-de-DEE I've a notion.
Liverpool.

Our correspondent has omitted to inform us of the site of the Fiddle-de-Dee; which we presume to be some tributary

branch of its classical namesake.