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lighted candle, which would sometimes be immediately extinguished as soon as
it sunk below this deadly stratum, would burn clearly at the very bottom.

It was very remarkable, that there was a whitish fog in the well, so thick
that one could but just see the dead bodies through it.

Water being scarce in that place, the well was left open for about 8 months,
in hopes the damp might at last wholly leave it ; but instead of that, it became
worse; and not confining itself within its first bounds, it overflowed at the
top, where, when the air was moist, it appeared like a thin white fog; and
when the air was dry, could be perceived like a warm breath, at all times dif-
fusing a sulphureous stench, something like that which arises from filings of
iron, while corroding with vinegar, affecting those who came into it with a
giddiness, shortness of breath, and propensity to vomit ; so that at last the
well was filled up, being troublesome to the family which lived near it.

The stratum abovementioned, which is continued to the neighbouring clift,
where, when heated with the summer's sun, it gives a noisome sulphureous
smell, and is, after moderate rains, covered with a yellowish efflorescent salt,
very astringent and acid. — On the shore below there are gathered pyrites.

P. S. The vein which was cut through in the middle of the well, from
whence were emitted the fatal effluvia, is a crude ore made up of iron, sulphur
and acid salts, mixed with pyrites.

These effluvia were not perceived till after the vein had imbibed the air for
several days. While the air continued dry, these effluvia subsided, and lay in
the lower part of the well, which seemed filled near to an exact level with the
stratum from whence they came.

But when the weather became rainy, the quantity as well as the impetus of



i46 PHILOSOPHICAL TRANSACTIONS, [aNNO 1738.

the effluvia increased to such a degree, as to appear in mornings over the top
of the well, in the form of a mist, and gave great annoyance to those who
came within its sphere of action. From hence it is worth observing, that the
same damp, according to the variation of the weather, is specifically heavier or
lighter than the air.

Concerning Magnets having more Poles than two. By Mr. John Eames,

F. R. S. N" 450, p. 383.

The sagacious Dr. Halley, in his account of the changes of the variation of
the magnetic needle, on the hypothesis of the earth's being one great magnet
having four magnetic poles, tells us, that he had found two difficulties not easy
to surmount; the one was, that no magnet he had ever seen or heard of, had
more than 2 opposite poles, whereas the earth had visibly 4, if not more, &c.
On looking over the copy of the Journal-book of this honourable society.
Vol. 2, an article is in the following words :

July 20, 1664, " Mr. Ball produced several loadstones, and among them
two terrellas, whereof one seemed to have 4 poles, with a circle passing be-
tween them, of no virtue at all. Some of the company suggested, that it
was probable this stone consisted of two stones, by nature cemented together
by a piece that had no magnetical quality in it; and if single, whether the re-
spective poles were opposite."

^n Account of some Magnetical Experiments, By J. T. Desaguliers.

N° 450, p. 384.

In the year 1715, trying some experiments on a very large weak loadstone,
the Dr. found that it had several poles. He then tried several other loadstones,
and often found 4 poles in such as had been armed when he took off their
armour. In large coarse stones he found sometimes 8, 9, or 10 poles. This
made him believe that all loadstones had several poles; but when he tried Lord
Paisley's loadstones, and other very good ones, he then found that homogene-
ous loadstones had but 1 poles ; those that have more being only an aggregate
of magnetic and other matter, which makes a heterogeneous substance. Such
is the society's great loadstone; for it has several poles.

An Account of some Magnetical Experiments made before the Royal Society,
By the Rev. J. T. Desaguliers, LL. D. F. R. S. N° 450, p. 385.

Dr. D. took a bar of iron, of l-4th of an inch diameter, which having been



i



VOL. XL.] PHILOSOPHICAL TRANSACTIONS. 247

15 years in an erect position, had acquired a fixed pole at top, so that the end
which had stood uppermost attracted the north end of a compass-needle, and
the other end the south end of the needle; and having susjjended it by a string
for the space of half a year, it acquired a fixed south pole at that end, as well
as it had done at the other in the time of 15 years, without diminishing the
virtue of the other end : so that both ends of the rod in any situation attracted
the north end of the compass-needle.

That rods of iron untouched, or which have not acquired a magnetic virtue
by their situation, will with their upper end, whatever end of the bar be held
upwards, attract the north end of the needle, and the lower end of the bar
the south end of it, is a truth known many years ago, and mentioned in Dr.
Brown's book of vulgar errors.

SoTne further Magnetical Experiments made before the Royal Society. By
Dr. Desaguliers. N° 430, p. 386.

It is well known, and has been often found by experience, that an iron bar
untouched by a loadstone, will, with its upper end, attract the north end of
the needle of a compass, when the said bar is held upright, and the south end
of the needle with its lower end, when applied to it, still in a perpendicular
position, whatever end of the bar be held up ; unless the bar has acquired a
fixed pole by having been long in a vertical position. But if the bar, from a
vertical, be brought to a horizontal position, the needle will return into the
situation it had before, which was in the magnetical meridian, the bar being
then at right angles to it. On raising or sinking the end of the bar which is
farthest from the needle, the one or the other end of the needle will begin to
move towards the bar. Such a bar has in itself no fixed magnetic virtue; but
if it had, it must be heated red-hot, and then cooled in a horizontal position.
A bar thus prepared, is fit to make the following experiments, communicated
by M. du Fay.

Hold the bar upright, and give it a blow or two against the ground with its
lower end ; and that end will attract the south end of the needle, when the
bar is held horizontal, and at right angles to the magnetic meridian : the other
end held horizontal in the same manner, will attract the north end of the
needle. Invert the bar, and its virtue will be lost by striking as many blows
with it against the ground with the other end : then strike another blow or
two, and the end which attracted the north end of the needle, will now attract
the south end ; and so vice vers&, the position being still horizontal. ,



'248 VHILOSOPHICAL TRANSACTIONS. [aNNO 1738.

If the blow be given against the ceiling, or any horizontal body, with the
upper end of the bar, the same virtue will be communicated as before.

This will likewise happen, if the upper or lower end of the bar be struck
with a hammer or mallet; whether the blow be given end-wise or at right angles
to the bar : nay, though it should be given in the middle of the bar ; the
position of the bar at receiving the blow being all that is requisite; for if you
give the bar only a jerk, or shake in that vertical position, it will receive the
virtue, as if there were in the iron several threads or beards fixed at one end,
as M. Du Fay supposes, which the blow or shake laid all one way, and which
were placed the other way by inverting the bar, and then giving it a shake
or blow.

When the bar is placed horizontally, a blow in the middle destroys its
virtue.

Of an Antique Metal Stamp, in the Collection of his Grace Charles Duke of
Richmond, Lenox and Aubigny, F. R. S. &c. being one of the Instances,
how near the Romans had arrived to the Art of Printing ; with some Re-
marks by C. Mortimer, M. D. Sec. R. S. Land. N" 450, p. 388.

Since arts and sciences, especially statuary and sculpture, were arrived at so
great perfection, when the Roman empire was in its glory, as the many beau-
tiful statues, the exquisite intaglias, and the fine medals, which time has de-
livered down to us, sufficiently evince ; it is much to be wondered at, that
they never hit upon the method of printing books.

The dies they made for their coins, and their stamping them on the metal,
was in reality printing on metal ; their seals cut in cornelians and agates, and
their pressing them on dough and soft wax, was another sort of printing; and
a third sort was the marking their earthen vessels, while the clay was soft, with
the name of the potter, or the owner the vessel was made for. These being
of a larger size, were properly called signa; the seals cut in stone were called
sigilla; sigillum being a diminutive of signum, as tigillum is of lignum: but
the later and more barbarous Latinists have formed the diminutive of signum
into signetum; and if a very small pocket-seal, they have called it signaculum.
See Joh. Mich. Heinecius de Sigillis. Francof. 1709, fol. p. 16, et seq.

The learned Montfaucon, among his immense treasures of antiquities, in
his Antiquite expliquee, Tom. 3, Part. id. Chap. 12, gives the figures and
descriptions of several of these larger sigilla or signa, on which he says, the
names were all cut in hollow in capital letters; and he imagines their use to



VOL, XL.] PHILOSOPHICAL TRANSACTIONS. 249

have been to mark earthen vessels, particularly those great earthen jars, in which
the Romans used to keep their wines. It any of them had occurred to him
with the letters excisae, exsculptae, protuberant or standing out, as the types
in our modern way of printing are made, so accurate a describer of antiquities
could not have passed it over without having mentioned it, and that the rather
because of its being a greater rarity : though several lamps of terra cocta are
stamped with letters impressed or hollow, from such protuberant letters as in
fig. 2, pi. 7, but the greater number have the letters raised, or standing out.

This stamp is made of the true antient brass, and is covered over with a
green scale or coat, such as is usually seen on antient medals. It was found in
or near Rome. On the back is fastened a ring, the hole of which is ^i of an
English inch one way, and ■!-§■ the other way ; the plate itself is two inches
long, wanting -^, and its breadth exactly 44 of an inch : the sides are parallel
to one another, and the ends are likewise parallel to each other, but they are
not on an exact square with the sides, varying about 1 degree and a half from
an exact rectangle. On the under side stand two lines or rows of letters, ^ of
an inch in height, and well-formed Roman capitals: their faces stand up, all
upon an exact level with one another, and with the edge or border of the
stamp ; their protuberance or height above the ground is different, the ground
being cut uneven ; for close to most of the letters the ground is cut away only
^V> close to some near -^, and close to the edges full -^. The first line con-
tains these letters, CICAECILI / , with a stop or leaf to fill up the line; in
the second line, HERMIAE. SN. Which is judged to be read Caii iulii
Caecili, Hermiae Signum. Who was probably a man in a private station, so
that his name has not been handed down to us in any monuments, but only
accidentally in this stamp. In Gruter occur two of the name of Hermias, and
several of the Caecilii, but none with these two names joined together.

The use of this stamp seems to have been for the signature of the above-
mentioned private man, to save him the trouble of writing his name, as some
people have at present. It was certainly used on paper or membranes, being
first dipped into ink, or some sort of paint, because of the protuberance of the
letters, the hollow letters being fitter for soft substances, on which they leave
the impression standing up, and consequently more legible. Another argu-
ment, that this stamp was not to be used on any soft substance into which it
might be pressed quite down to the ground, is the unevenness and roughness
with which the ground is finished, which, was it to have made part of the im-
pression, the workman would have finished with more accuracy; but he, know-
ing that the surface of the letters was to perform the whole work required, was
only attentive to finish them with that accurate evenness that these have.

VOL. vni. K K



250 PHILOSOPHICAL TRANSACTIONS. [anNO 1738.

Mattaire, in his AnnalesTypographici, Hagae 17I9, in 4to, p. 4, concludes
from the best authors, that our modern art of printing was first thought of
about the year 1440. A copy of the book he mentions, ib. p. 13, called Spe-
culum nostrge Salutis, being pictures of stories out of the bible, with verses
underneath, in Dutch, is in the Stadhouse at Haarlem. Each page was printed
from a block of wood, like a sorry wooden cut; and this was the first essay of
printing, which hint was taken from engraving, and is what he means p. 4, by
typi fixi; after which they soon improved to use separate types, as we do now,
which he terms, ibid, typi mobiles.

This stamp is, in reality, a small frame of fixed types, and prints with our
modern printer's ink, which is only a sort of black paint, as readily as any set
of letters, cut in the rude manner these are, can be expected to perform.

We see by this stamp of two lines, that the very essence of printing was
known to the Romans, and they had nothing to do but to have made a stamp
with lines three or four times as long, and containing twenty instead of two
lines, to have formed a frame of types that would have printed a whole page,
as well as Coster's wooden blocks, which he used in printing the Speculum
Salutis.

In the first volume of a collection of several pieces of Mr, John Toland,
printed Lond. 1726, in 8vo. p. 2Q7, is a small tract of his, entitled, Conjec-
tura verosimilis de prima Typographise Inventione, which is founded on the
following passage in Cicero, in cap. 20, lib, 2, de Natura Deorum ; where
Balbus the stoic uses the following words in an argument against Velleius an
Epicurean.

Hie ego non mirer esse aliquem, qui sibi persuadeat, corpora quaedam solida
atque individua vi et gravitate ferri; mundumque effici ornatissimum et pul-
cherrimum, ex eorum concursione fortuita ? Hoc qui existimet fieri potuisse,
non intelligo cur non idem putet, si innumerabiles unius et viginti formae lite-
rarum (vel aureae vel quales libet) aliquo conjiciantur; posse ex his in terram
excussis annales Ennii, ut deinceps legi possint, effici; quod nescio an ne in uno
quidem versu possit tantum valere fortuna.

He conjectures that this very passage gave the first hint to the inventors of
printing about the year 1445, because they retained even Cicero's name for
their types, calling them formae literarum, and made them of metal, as he says,
aureae vel quales libet. Moreover, in cap. 10, lib. 3, de Divinatione, Cicero
has the very phrase imprimere literas.

Brands for marking cattle were in use in Virgil's time, Georg. lib. 3, ver. 158,
where he says,

Continuoque notas, et nomina gentis inurunt.



VOL. XL.] PHILOSOPHICAL TRANSACTIONS. 25 1

Procopius, in his Historia Arcana, says, the emperor Justinus, not being
able to write his name, had a thin smooth piece of board, through which were

cut holes in form of the four letters^ W ^'HT' which, laid on the paper,

served to direct the point of his pen; which being dipped in red ink, and put
in his hand, his hand was guided by another. Possibly this may likewise have
given the hint to the first of our card-makers, who paint their cards in the
same manner, by plates of pewter or copper, or only pasteboards, with slits in
them in form of the figures that are to be painted on the cards.

An Occultation of Mercury by Venus, May 17, 1737} observed at the Royal
Observatory at Greenwich. By J. Bevis, M. D. N" 430, p. 394.

At Q** 43"* 4' p.m. app. time. Mercury was only the 10th or 12th part of
Venus's diameter distant from her; afterwards the view was intercepted by
clouds.

At 9*" 51™ 10' Venus shone out again very bright, and Mercury was quite
covered by her. Afterwards clouds again prevented any further view of the
phenomenon.

Of a netv Azimuth Compass, for finding the Variation of the Compass or Mag-
netic Needle at Sea, with greater Ease and Exactness than by any ever yet
contrived for that Purpose. By Capt. Christopher Middleton, F. R. S.
N° 450, p. 395.

To discover at sea the declination of the magnetic needle, or variation of
the compass, with some tolerable degree of certainty and exactness, is a thing
of great use and importance in the art of navigation. The instruments and
methods hitherto used for this purpose, are subject to several inconveniencies,
errors, and defects; to remedy which, this new azimuth compass was contrived,
which has by experience been found effectual. It would be needless to give a
description of the instrument; the cap therefore only shows the manner of
using it, which is as follows:

1 . The instrument must be rectified, or fitted for observation, by turning it
about till the 4 cardinal points, that are hung on the centre pin, agree with
the 4 cardinal points on the chart, at the bottom of the box ; then will the
needle, that shows the magnetic meridianj stand at no degrees, and the east
and west points at go degrees, on the graduated circle within the box ; and in
this situation it must be kept, as near as may be, during the whole time of the
observation.

2. Let the index of the quadrant be placed to that degree of the arch, on

K K 2



'25'2 rHlLOSOPHICAL TRANSACTIONS. FaNNO J 738.

the rim of the box, which the observer judges to be nearly equal to the height
of the sun or star whose azimuth is sought; for by this means the object will
be more readily found.

3. Turn the quadrant round towards the sun or star, till it appear on the
vertical hair within the telescope, to an eye looking through the small hole or
sight; and then slide the index a little upward or downward on the arch, till
the object by this means be brought to coincide or touch the visible horizon.

Lastly, The degrees and minutes then marked by the index on the arch of
the quadrant, will show the altitude of the object, which will always be the
same, whether the instrument be in motion or at rest; at the same time the
degree cut by the index on the horizontal rim, or circumference of the compass
box, will give the magnetical azimuth of the sun or star.

How the variation of the needle is found by means of magnetical azimuth
and altitude thus obtained, is taught in every treatise of navigation. But as
the resolution of this problem is somewhat troublesome, and requires such a
knowledge of the doctrine of the sphere, as every seaman has not attained, an
easy method is here exhibited of discovering the variation of the compass with-
out any manner of calculation.

1 . Let the magnetic azimuth of the sun, or any star, when it is near the
prime vertical, and considerably elevated above the horizon, be found according
to the directions already given, before it arrive at the nieridian, and note well
the altitude, or let the index remain fixed at the same point on the arch.

2. Find the magnetic azimuth of the sun or star in like manner as before,
when it is exactly at the same degree of altitude, after it has passed the meri-
dian: and,

3. If these two magnetical azimuths be equal, the needle has no variation;
if urrequal, add them together, and half their sum will be the true azimuth;
or subtract the less from the greater, and half the difference will be the varia-
tion required. The circumstances of the observation will the more readily dis-
cover whether the declination is easterly or westerly.

N. B. Though it would be very commendable in gentlemen who use the sea,
to learn the names of most of the principal fixed stars, yet even that knowledge
is not necessary in the use of this instrument: neither is it needful in this case
to know exactly the latitude of the place of observation, provided the difference
of latitude between the observations be not very great; it is sufficient, that
care be taken to observe the self-same star, before it comes to the meridian,
and after it has passed it; and for the sake of greater exactness, the caution
before given should be regarded, viz. that the star be at some considerable
height above the horizon, and also near the prime vertical.



VOL. XL.]'' PHILOSOPHICAL TRANSACTIONS. 253

:in

An Account of a Book presented to the Royal Society, entitled, Notitia Hungaria
novie Historico-Geographica, &c. Auctore Matth. Belio. By the Rev._
Zachary Pearce, D.D. F.R.S. &c. N"450, p. 398. ,,j

The author of this work is the Rev. Matthias Bell, a pastor among the Lu-
therans at Presburg in Hungary.

This first volume is to be followed by several others; for the kingdom of
Hungary includes 48 districts or counties, and this volume gives an account of
only one of them, and indeed is chiefly taken up with the history of the city of
Presburg, or Pisonium. as he calls it, which, though inferior in other respects
to the city Buda, is the place where the emperors, as kings of Hungary, are
crowned, where the states of the kingdom assemble, and the courts of justice
are held.

This volume consists of two parts. The first is general, and gives an account
of the physical and political state of the whole district or county of Pisonium,
describing its soil, produce, rivers, the temperature of its air, the nature of its
inhabitants, its ancient inhabitants and present ones, its nobility, magistrates,
and whatever belongs to the natural and political history of the district.

The second part is occupied with the description of the city Presburg; where
the author is very copious and elaborate in setting forth every thing that relates
to it, particularly its ancient state under the several nations who possessed it,
and its present state under the Austrian family. Leaving to the next volume
the description of the 4 other cities or principal towns, situated in the same
district. .^

•II

yi short Account of Mr. KerssehooirC s Essay, on the number of People in Holland
and West Friezland, as also in Haarlem, Gouda, and the Hague; drawn from
the Bilk of Births, Burials, or Marriages, in those Places. By John Eames,
F.R.S. N°450, p. 401.

It is well known to what useful purposes the bills of births and burials, at
the city of Breslau, the capital of Silesia, have been applied, by Dr. Halley;
as also what curious observations have been made, both moral, physical, and
political, by Sir William Petty, on the same argument, several years before,
and by Dr. Arbuthnot and others since. Our industrious author has not only
consulted them, but acquainted himself more particularly with Mr. King's ob-
servations in Davenant's Essays, &c. in order to render himself more capable
of making a just estimate in this matter.

He begins with the number of inhabitants in the two provinces of Holland



254 PHILOSOPHICAL TRANSACTIONS. LaNNO]738.

and West Friezland; these he makes at this time, viz. 1738, to amount in all
to 980,000, and gives the following table of the particulars. It exhibits the
number of people of all ages, living at the same time, from the birth to ex-
treme old age; which, because it shows the chances of mortality within the
ages mentioned, he calls the table of contingency of life and death.

The Table of Contingency.



Of above QO years old there are 500

of QO to 86 inclusive 2,500

85 81 6,500



Of



80..
75..
70..
65..
6o. .

55. .
50, .
45. .
40..
35..
30..



.76 13,000

.71 20,300

.Q6 27,300

.61 34,300

.56 40,8O0

.51 47,000

.46 53,000

.41 57,800

.36 62,500

.31 67,600

.27 58,400



26
20.
15.
JO.
5.



to



21 94,300

16 83,400

11 87,200

6 91,800

birth 131,800



sum under 27 years
ditto above 27 years



,488,500
,491,500



sum of all the inhabitants980,000



sum above 27 years 491,500

This table is founded on three principles, viz. correct observations on the
tables of assignable annuities in Holland, which have been kept there for above
125 years; in which the ages of the persons dying are truly entered; on a sup-
position that there are yearly born in the two provinces 28,000 living children;
and lastly, that the whole number of inhabitants in any country, is to the
number of the births, as 35 to 1.

From this table it appears, 1. That about half the number of people in the



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