ber, as a foffil, is unknown, but it is to move freely, will place itself in one probably of a mineral species, being a and the same position with respect to kind of bitụmen, that was once in a the points of the compass, for many fluid or very soft ftate, as is evinced by years together, without any sensible the number of extraneous objects ob- alteration. If an artificial magnet, or served in it, such as straws, or small in- what is usually called a magnetic nee. fects, and that it was hardened into it's dle, has a brass cap fixed in it's centre, present state hy a mineral acid of the with a conical hole on the lower fide, nature of spirit of sulphur, oil of vi- by which it may be suspended on triol, &c. The native colour of am- the point of a pin in the centre of a ber is yellow; it is transparent to a

circle divided into thirty-two equal considerable degree, of a hard, com- parts, then this needle being truly pact consistence, admits of a very high equipoised, will, after several vibrapolish, and is of an inflammable na- tions, settle itself in a position directed ture, and supposed to be soluble in to one of those divisions on the circle, certain menftruums.

called the thirty-two points of the Tourmalin, is a gem, or jewel, compass. The noble art of navigation which the Dutch artifts first discover depends wholly upon the magnet, or ed to possess an electric power; for, the variation of the needle it occain heating it by grinding and polish- fions. This variation of the needle is ing, they observed that it attract- in itself variable, the situation and died alhes, and other light bodies near

rection of the needle in any one place it. As electricity is of two forts, am- gradually altering, so as, in a course of ber possesses one, and glass the other: years, to become sensible: thus, at but the tourmalin possesses them both; London, the variation was a whole or, rather, both forts may be excited point to the east about a century ago; . in it, the positive on one side, and the afterwards it veered to the north, and negative on the other. The mode ofex. at last came precisely into the plane citing electricity, in amber and glass, of the meridian of London, so that is by rubbing; but, in the tourmalin, then there was no variation at all. by heating it only. Thus, if it be Ever since that time it has been veerheated by fire or hot water, one fide ing westward, and is now more than will attract and the other repel light twenty-one degrees to the weftward bodies; but it is of too small a bulk to of our meridian. But this proves no afford these powers in quantities and impediment to navigation; because, strength sufficient for practical uses. if the quantity of it be known at any

The Magnet, or Loadstone, is a time, there is nothing more requisite. foffil which has the singular property In order to render a needle magnetiof attracting and repelling iron, but cal, the north part must be made fomeno other body, unless it be the same what lighter than the southern, for in substance.' There are two parts in otherwise it would not stand level, every magnet, called it's poles, from but dip below the horizon: but this one of which issues an attractive, and dipping of the needle, and the varifrom the other a repulfive power.ation, tend to the same thing; only This is universally the case in every the former is in a vertical plane, while piece of magnet, great or small; and the latter is in a horizontal one.

The it's power is communicable to iron, needle dips with us about seventy debut to no other substance. The mag- grees below the horizon; but this netic iron is then called an artificial dipping is of no use to mariners, be. magnet, and acts in every respect like cause made in the plane of the meri. the natural one. This power circu- dian. In communicating this virtue lates from one pole to the other, on

to the needle, three things are very every fide; therefore, every magnet carefully to be observed: first, that it is in the centre of a magnetic vortex be touched by an artificial magnet, or atmosphere of it's own power. as the power is much greater than in Every magnet, when in a condition a natural one; secondly, that each


Z 2

end of the needle be touched at the init's common appearance, much like same time, the north end of the nee other cryitals, pellucid and clear as dle by the south pole of the magnet,

water: it also

grows, like them, from and the south end of the needle by the the hardelt rock and stone, in form of north pole of the magnet; thirdly, hexagonal pyramids, with very sharp that, in touching, the magnets are al- points. When these large crystals ways to be drawn from the middle to are broken off the stone, and into the ends of the needle This last cau- many different pieces, each piece, tion is particularly necessary, because whether large or small, is precisely what is gained by drawing the mag- of the same form, or quadrangle, havnet one way, is loft by drawing it the ing fix fides, and the two opposite other; and the second precaution is ones exactly parallel to each other. also necessary, because the same polar Every piece has the same form and virtue in the ends of the magnet and attributes. It has the peculiar proneedle makes them repel each other, perty of double refraction; so that a and consequently the end of the nee beam of light, instead of passing dle that was touched by the south through it fingly, and entire, as in pole of the magnet will be repelled glass, is divided into two or more afterwards by it. Though there beams of light; and the object view. must be a something to actuate the ed by the fame light is divided in like needle at sea, nothing that is abso manner into two or more objects. lutely invisible can affect the needle Naturalists have hitherto considered but 'magnetism : it is therefore evi- only two refracted beams in this crydent that nothing besides the earth ftal; but it has been found, on grind. itself can be the magnet in question; ing and polishing several pieces into fince a magnetic vortex from the earth the form of prisms, that the refracalone can be fufficient to account for tion is not only double, but manifold; the phænomena of the needle on every and that a variety of prisms produce part of it's surface. But the poles of a great variety of refractions, and it's magnetism can never be in the present as great a number of images poles of the globe, or in the ends of to the view of one and the same obit's axis, because in that case there jeet. Some shew but two images, could be no variation of the needle, others three, four, fix, twelve, fixteen, but a dipping only. Neither can they and even twenty; which demonftrates be fixed in any other partof the earth's that there is a refraction of one beam furface, for in such case there would of light into as many different parts. be a constant variation in the same Each image is at the same time tinged place. There must, therefore, ne- with a variety of prismatic colours, , cessarily be an internal magnet in the fome of which are intensely strong and earth, which is moveable, and con- bright when the object is luminous, ftantly altering it's position, or direc as the window, a candle, or the fun. tion of it's axis. The strength of na The Asbestos, or' Amianthus, is tural magnets is estimated by their possessed of very fingular and extrablackness, hardness, and the weight ordinary qualities; and that strange they are capable of lifting compared and surprising one, peculiar to this with their own. Those which will foffil, by which it refifts the force take up "twenty times their own of the strongest fire, renders it a subweight are reckoned very good. ject of the greatest admiration. One Others will take up thirty times their fide of the Asbestos exhibits nothing own weight, but such are rarely to be remarkable in it's appearance; but the met' with.

other has a delicate and beautiful fur, Mand Crystal is the fairest and most face which appears like the finest green delicate" fofil produced by the earth, filk or sattin, or rather a sort of petri, and of the greatest celebrity among fied cotton or silk; filky filaments seem. philosophers, as well as naturalifts, ing to run through the whole length, for it's fingular and amazing property and to compofe the entire surface. of a double refraction of light. It is, The firmness of it's texture, and the


natural polish of it's fibres, gives the which you mention concerning the whole a delightful gloss; and when 21,-57, 16, 3, 44, 5, 19, 53, 33, 205; those fibres, or filky filaments, are 222, 208, and that which is intended raised up with the point of a needle, after; but whosoever will join with they appear of a very different form me muit come to my grounds, a chief and colour, resembling an assemblage part whereof is the including my of the softest filky substance, and friends, without which I assure you no whiter than the purest cotton; so that agreement shall be made; this army they might easily be wrought into a speaks me very fair, which makes me web of fine filk stuff or cloth. There hope well, but it must be their actions, is much of this fossil in England, but not bare words, which will make inę it is of an inferior nature, and confe- trust them: I have declared for my quently of very little value; the best going to Richmond, from which nofossils of every kind, except Mundics, thing shall (by the grace of God) diare indeed met with in warm regions. vert me (if the two Houses do not

Mundic is a species of that fort of recede from their votes) but direct marcasite which is chiefly remarkable force, which I hope the army will not for it's great variety of the most in- offer to do, for if they mean well, tense, glorious, and glowing colours, this my journey will be available to any where to be found in nature. them, and, whatever they intend, Mundic may be said to wear the rich- forcing of my person will do them eft livery of the Deity, there being no more harm than good. I desire that bodies of the animal or vegetable class this may serve for those two honek whose refulgence is comparable to that men whose letters came with yours, of the finest fort of mundic. It's re- defiring them, as also all my other fplendent colours are innate and per- friends, not to engage particularly to manent, and are heightened to an asto- either party, but itay to declare as I nishing degree. They have the great- Thall do, for I am neither indepenest variety of all prismatic colours in dant nor presbyterian, but shall be deeper dyes than in any other bodies moft for them who are most really for with which we are acquainted; viz. the peace of the kingdom, according the red, orange, yellow, green, blue, to the known laws. °So farewell. indigo, purple, violet, and every

C. R. other known colour. The more they are magnified, the stronger they ap

LETTER II. pear; and, when they are properly

7 AUG. placed in the opake folar microscope, I Acknowledge that what 222: 127 and magnified about forty times in sent to you for the loan of your diameter, they exhibit such scenes of cypher was by my directions, it being glory as are perfectly ineffable, and to that end as was mentioned, and cannot be conceived without viewing that the ticket was mine, which I .them.

thought sufficient to have made you done what is required; but I confess

that too much caution is a moft ex THREE ORIGINAL LETTERS cusable error, and I will not say but OF KING CHARLES THE FIRST, TO

that my direction was too laconic; FLEETWOOD, LATELY PRESENT

however I desire you to lend 222, 127, ED TO THE BRITISH

cypher, as 65,6, 18, 11, 367, defired BY A DESCENDANT OF

as being a person whom you may FLEETWOOD.

trust. This I have written before I

have decyphered the latter part of LETTER I.

your letter, that mine


be no lonNEWMARKET, 21 JUNE 1647.

ger useless to 222, 127: fo farewell. I Than Thank you for your cypher and If there be any thing to answer to

your advertisements, and shall yours, you shall learn from me very npt milike if that should happen thortly.





is feparated from the air, in the proL ETTER III.

7 AUG. 1647. cess of respiration, it would fink zo de. HIS morning I answered the for- grees. Hence, if the evaporation from

mer part of your yesterday's let- the lungs be so much increafed as to ter, in which I find another mistake, carry off the whole of the heat that is after I had decyphered the latter, for detached from the air, the arterial I see you thought T. A. had written blood when it returns by the pulmo the note which was sent you for the nary vein will have it's sensible heat loan of your cypher, but I affure you greatly diminished, and will confeit was 367, 184, 108, whereforequently absorb heat from the vessels again I defire you to lend it 166, who which are in contact with it, and from sends you this; and hereafter, when the parts adjacent. The heat which my name is used to you,

of which you will again be extricated in the ca

is thus absorbed in the greater vessels make any doubt, send immediately to me and none else. So farewell. pillaries, where the blood receives a

C. R. fresh addition of phlogiston. If, in

these circumstances, the blood during

each revolution were to be equally PHILOSOPHICAL TRANSACTIONS.

impregnated with this latter princiEXPERIMENTS ON THE POWER OF ple, it is manifeft, that the whole ANIMALS TO PRODUCE COLD." effect of the above process would be

to cool the system at the centre, and (Concluded from Page 105.)

to heat it at the surface; or to conShall I now endeavour, from the

the heat to that part of the body preceding facts, to explain what where it is capable of being instantly appear to me to be the true causes of carried off by evaporation. But it the cold produced by animals when appears, from the experiments which placed in a medium, the temperature have been laft recited, that, when an of which is above the standard of animal is placed in a heated medium, their natural heat. In a work which I some time ago revolution, is less impregnated with

the fanguineous mass, during each laid before the public, having, at- phlogiston; for' we have feen, that tempted to prove, that animal heat the venous blood, in these circumdepends upon the separation of ele- ftances, becomes gradually paler and mentary fire from the air in the pro- paler in it's colour, till at length it cess of respiration, I observed, that acquires very nearly the appearance when an animal is placed in a warm of the arterial: and it is rendered medium, if the evaporation from the highly probable by the experiments of lungs beincreased to a certain degree, Dr. Priestley, that the dark and livid the whole of the heat separated from colour of the blood in the veins de. the air will be abforbed by the aqueous pends upon it's combination with vapour.

phlogiston in the minute vefsels. From the experiments on venous Since, therefore, in a heated medium, and arterial blood, recited in the third this fluid does not affume the same lisection of that work, it appears, that vid hue, we may conclude, that it does the capacity of the blood for con

not attract an equal quantity of the taining heat is fo much augmented phlogiftic principle*: in the lungs, that, if it's temperature It follows, that the quantity of were not supported by the heat which heat given off by the blood in the

It is of no consequence in the above argument, whether we suppose, with Dr. Priestley, that the alteration of colour in the blood depends upon it's combination with phlogiston in the capillary arteries, or maintain with some other philofophers, that this alteration arises from a change produced in the blood itself by the action of the vefiels; it is sufficient for our purpose to assume it as a fact, which, I think, has been proved by direct experiment, that, in the natural state of the animal, the blood undergoes a change in the capillaries, by which it's capacity for containing heat is diminished; and that in a heated medium it does not undergo a similar change.



capillaries will not be equal to that of the weather, and the difference of
which it had absorbed in the greater season and climate: for, as soon as
vefsels, or positive cold will be pro- by exposure to external cold, an un-
duced. If the blood, for example, in usual diffipation of the vital heat is
it's passage to the capillaries, absorb produced, the blood, in the course of
from the greater vessels a quantity of the circulation, begins to be more
heat as 30 degrees, and if in conse- deeply impregnated with the phlo-
quence of it's receiving a less impreg- giftic principle. It will therefore
nation of phlogiston than formerly, it furnish a more copious supply of this
gave off at the extreme vessels a quan- principle to the air in the lungs, and
tity of heat only as 20 degrees, it is will imbibe a greater quantity of fire
manifeft, that upon the whole a de- in return.
gree of refrigeration will be produ In summer, on the contrary, the
ced as 10 degrees, and this cause of reverse of this will take place, less
refrigeration will continue to act while phlogiston will be attracted in the mi.
the venous blood is gradually assum nute vessels, and less fire will be ab.
ing the hue of the arterial, till the forbed from the air.
difference between them is obliterated; And hence the power of generating
after which it will cease to operate. heat is in all cases proportioned to
Thus it appears, that when animals the demand. It is increased by the
are placed in a warm medium, the winter colds, diminished by the sum-
fame process which formerly supplied mer heats: it is totally suspended or
them with heat becomes for a time converted into a contrary power, ac-
the inftrument of producing cold, and cording as the exigences of the ani.
probably preserves them from such mal may require.
rapid alterations of temperature as

From the changes which are promight be fatal to life.

duced in the colour of the venous Upon the whole, the increased eva. blood by heat and cold, we may like. poration, the diminution of that pow. wise perceive the reason why the temer by which the blood in the natural perature of the body is frequently in. ftate is impregnated with phlogiston, creasedby plunging suddenly into cold and the constant reflux of the heated water, and why the warm bath has fluids towards the internal parts, feem such powerful effects in cooling the to be the great causes upon which the system, and in removing a general or refrigeration depends. Having found partial tendency to inflammation. that the attraction of the blood to phlo. giston was diminished by heat, it appeared probable, on the other hand, that it would be increased by cold. To QUAKES IN CALABRIA, SICILY, determine this, a dog at 100 degrees

&c. COMMUNICATED TO THE was immersed in water nearly at 45

LIAM HAMILTON. degrees. In about a quarter of an hour a small quantity of blood was taken

NAPLES, MAY 23, 1783. from the jugular vein, which was evi Am happy now to have it in my dently much deeper in it's colour than that which had been taken in the warm thren of the Royal Society, fome lit. bath, and appeared to me, as well as to tle idea of the infinite damage done, several other gentlemen, to be the and of the various phænomena exhi. darkeft venous blood we had ever feen. bited, by the earthquakes (which be

From this experiment, compared gan the 5th of February laft, and with thofe which have been recited continue to be fenfibly, though less above, we may perceive the reason violently, felt to this day) in the two why animals preserve an equal tem- Calabrias, at Messina, and in the perature, notwithftanding the great parts of Sicily neareft to the contivariations in the heat of the atmo

From the moft authentic re: phere, arising from the vicissitudes ports and accounts received at the





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