s E c


[4+0]


And !. itf/itide. Yet Scaliger, in his Anfwer to S rrrils,
gives a different Explication. in cffeft, all that has
hitherto been advanced on this Point, Is mere Conjec-
ture.
SECANT, in Geometry, a Line that cuts another, or
divides it into Two Parts: Thus the Line A Ml (Cab.
Geometry Fig. z )) is a Secant of the Circle A E D, Oc.
as it cuts the Circle B. 'Tis demonftrated by Geom eters i
* a That if feveral Secants M   A, MN, M   Ec.  be
drawn from the fame Point M, that paffing through the
Centre M. A, is the greate ,   and the tell are all ho much
the cis, as they are more remote from the Centre. On
the contrary, the Portions thereof without the Circle
I D, M    0, M  BB are. fo much the greater, as they are
further from the Centre. The leaf, is that of M   A, which
pates through the Centre. 2o That if Two Secants M A
ana d I   E, be dGrinm from the fame Point M;   the Secant
MA, wilIbe toME aJ AMDtoMB. SeeTANGENT.
SUcANT, in Trigonometry, a right Line, drawn from
the Centre of a Circle, which cuttiog the Circumference,
proceeds, till it meets with a Tangent, to the fame Circle.
Thus the Line F C (Tab. Trigonometry Fi v.) drawn
from the Centre C, till it meet the Tangent IF, is call'd
a Secant, and particularly the Secant of the Arch A E,
to which FIE is a Tangent. The Secant of the Arch
A H, which is the Complement of the former Arch to a
Quadrant, is call'd the Co-Secant, or Secant of the Com-
pienent.
The Sine of an Arch AD, being given; To find the
Secant thereof F C, the Rule is, As the Co-fine ADC is
to the Sine A D, l o is the whole Sine E; C, to the Secant
C F.
To find the Logarithm of the Secant of any Arch:
The Sine of the Complement of the Arch beig given
multiply the whole Sine of the Logarithm  by Two, and
from ti.e Produdt lubtraq the Logarithm of the Sine
Complement, the Remainder is the Logarithm of the
Secant. See LOGARITHM.
Line of SECANTS. See SECTOR.
SECOND in Anatomy. See SECUNDI GxNER IS.
SECOND in Geometry, Aft ronormy, &c. the Sixtieth
Part ot a Prime or Minute; either in the Divifion of Cir-
cles, or inthe Mealure of Time. ADegree,or an Hour, are
each divided into 6o Minutes, marked thus ': A Minute
is lubdivided into 60 Seconds, marked thus'; a Second
into 6o Thirds, marked thus "', Uc. See DEGREE. We
lometimes fiy a Second Minute, a Ib ird Minute, L'c.
but more ufually, limply Second, K aird, .efc. A Pendulum
Three Feet Three Inches, and two Tenths of an Inch
long, vibrate's Sccndi: According to Sir Jonas Moor's
Redq6ion of Hujgen's Three Feet Eight Zries and an
Halt of Paris Meafure, to Evglij0 Mcafure. See PEN-
DULUMN.
SECOND in M fick, one 6f the mufical Intervals;
being only the Diflance between any Sound, and the
next nearell Sound; wherter higher or lqwer. See IN-
TERvAL. As in the Compafs of a Tone, there are
reckoned Nine fenfible. different'Sounds, which form
shole little Intervals, call'd Gommas; one might, in firl-
ie s, fay, there are Eight kinds of Seconds. But as themf
minute Intervals, though fenlible, are not yet fo far fo,
as to contribute much to the Harmony, they ufually only
diffinguifh four Sorts. The Firfi called, 'ITe dimiuip'd
Seconi, containing Four Commas, and is the Diffe-
rence, for Inriance of a natural ut, and an at railed
four Commas higher. The Second, calld Second Minor,
contains Five Commas, and is made either naturally as
from mi tofa, or from fi to ut; or accidentally, by means
of b, as from ta to /i, bftat; or from fa diefis to jol;
otherwife called a MlajorSemitone, or miperfe zISecond,
or Italian Semitone. The Third is the Maror Second,
containing the Nine Commas, which compo t the Tone.
This the Italians call 70070 orper Sc   The Fourth
is the Second Redundant, compofd of a whole Tone and a
minor Semitone.
SECOND 'ehmS, in Algebra, thofe where the un-
known Quantity has a Degree lefs than it has in the
Term where 'tis rais'd to the highefd. The Art of throw-
ing thefe Second Terms out of an Equation; that is, of
forming a new Equation, where they have no Place, is
one of the mofd ingenious and ufeful Inventions in all
Algebra. See REDUCTION of EFuatiwzs.
SECOND Captain, is a reformi'd Captain, who ads
as Lieutenant of another, into whofe Company he is In-
corporated. See CAPTAIN.
SECOND Carqfe. See CAUSE; and EPICILNT.
SECOND Sfght, an odd Qualification, many of the
Inhabitants of the Wefiern Iflands of Scotland are faid to
be pfefs'd of. We have the Thing fo well atre'led, by
fo many credible Authors (the latel of whom is Mr AMar-
tin, the Ingenious Author of the natural Oiflory of tchfe


S E C


iflands, and a Member of the Royal Scciety) that, notv
banding the Quaintrnef of the Thing, there is Icarce R
to call it in Q~ettion. The Second ~Yzbt, is a Facual
feeing Things to come, or T s hings doing at a Sreal
fiance, reprefenred to the Imagination as if-h
vifible and prefent. Thus if a hqan be dying, or a
to die, his Image Shall appear diftindly in Jts nai
Shape, in a Shroud, and with other funeral Appar
to a Second Sghted Perlon, who, perhaps, never fiat
Face before: Immediately after which, the Perfon o f
certainly dies. This Qalityfof Second   Sighteinefi js
hereditary: The Perton who has it, cannot exert
pleafiree nor can he prevent it, or communicate
another; but it cones on him involuntarily, and exer
itfelf on him arbitrarily. And often, efpcically In
younger Second &ers, to their g ree t Trouble and Te
There are a great Number of Circumltances attend t
Vitions, by Obtervation whereof, the particular Circ
fiances as to Time, Place, &'c. of the Death of the
fon , are learnt. The Method of judging of them, or
terpreting them, grows into a kind of Art; which is
diff erent in differen t Perfons . Second Sigbtedizes, is
a Difcredit among them i   fo that none will counterfei
many conceal and difi'emble it.
SE  CONDARY Circles, in reference to the Eclip
or Circles of Longitude of the Stars, are luch, as pal
through the Poles of the Ecliptick, are at right Anglh
the Ecliprick (as the Meridian and Hour Circles ar
the Equinoaial). By the Help of thele, all Points in
Heavens are referred to the Ecliptick i   that is, any '
Planet or other Phznoinenon, is underfiood to be in
Point of the Ecliptick, which is cut by the Secom
Semicircle, which paeies through fiuch Star or Piizn4
non. And if two Stars are thus referr-d to the lame I
of the Ecliptick, they are faid to be in Conjundiot
in oppofite Points, they are faid to be in 0Upofit
If they are referred to two Points at a Quadrant's Dita,
they are faid to be in a Quartile Al&eeat; if the PI
difer a fixth Part of the Ecliptick, they are Laid v


in a Sextile Aloe&. And in general, all Circles which in-
terfea one of the Six greater Circles 'of the Sphere at
Right Angles, may be called Secondary Circles; as the
Azimuth or Vertical Circles in refpedk of the Horizon,
0,C.
SECONDARY Fever, is that which arifes after a
Crifis, or the Difcharge of fome morbid Matter, as after
the Declenfion of the Small Pox, or Meafles; and fuch a
Fever is frequently dangerous. See FEVER.R.
SECONDARY Planets, thofe moving round other
Planets, as the Centres of their Motion, and along with
them round the Sun. See PLANET.
Saturn,  7upiter, and the  Erth,  are each attended
with Secondary Planets  Jupiter  with four, and Saturu
with five, called the Satellites of thofe two Planers. See
SATELLITES. The Earth with one called the Moon.
See MOON.
The Motion of the Primary Planets, is very fimple and
uniform, as being compounded only of a Proje&ile Motion,
forward in a right Line, which is a Tangent to the Orbit,
and a Gravitation towards the Sun at the Centre. Add,
That being at fuch vafl Diffances from each other,
the Effeas of their mutual Gravitation towards one ano-
ther are infenfible: But the Matter is far otherwife, in
refpe& of the Secondary (Planets;  for every one of thefe,
though it chiefly gravitate t~wards its refpefive Prima-
ry One, as towards its Centre, yet  at equal Diflances
from the Sun, is attrailted towards him with equally acce-
lerated Gravity  as the primary One is towards him, but
at a greater Dianc with lefs, at a nearer Diflance with
greater; from which double Tendency towards the Sun,
and towards its own Primary Planet, the Motion of the
Satellites, or Secondary Planets, comes to be mightily
compounded, and affeded, with many Inequalities: As
for In fance, (r.) The Satellite Ihall be continually acce-
lerated in its Motion, from the Time of its QuadraturC
with the Sun, to the next following Conjuncion or Op-
pofirion; but contrary-wife from the Syzyoies to the
tQuadratures, it Ihall be retarded, and therefore will not
always move fwifter in or near the Syzygies, and flower
niear the Quadratures. From whence will follow, (2.) Thar
the Orbits ofthefe Secsndary Planets, will be of a Figure
more Circular in the Quaalratures than in the Syzygies.
where the Swiftnefs of the Motion will make the Figure
of the Orbit more Redilinear, and therefore the satellite
will run farther from its Primary Planet at the Quadra-
tures, than at the Syzygies, fo that the Orbit wilr be a
little elliptical, having the primary Planet for its Centre,
aWa the longer Diameter will coincide with the Line of
the Quadratures, and the fhorter.with that of the SyzY-
Ries.  Which  Irregularities will arife, if the Sun's
Power of perturbing the Motion qf the Satellite be ex-
cluded, and tht Orbit be cocentrick wi1h that of the
Primary