M A N 
MAN 
of our years better than their number can be efti- 
mated by Arrangers; and as thofe are feldom de- 
ceived who judge of our age by external charac- 
ters, we would be ftill more fenfible of it from in- 
ternal figns, if t'i were more attentive to our feel- 
ings, and deceiv*:! not ourfelves by vanity and 
fallacious hopes. 
When the body has acquired it's full flature, 
and is extended to it's juft dimenfions, it begins to 
increafe in thicknefs; and this augmentation is 
the lirfb ftep towards a decay, being merely an ad- 
dition of fuperfluous matter, which inflates the 
body, and loads it with an ufelefs weight : this 
matter, which is denominated fat, about the age 
of thirty-five, or forty, begins to cover the muf- 
cles, and interrupt their aftivity; every a6lion then 
requires a greater exertion to perform it; and the 
increafe of fize is at the expence of eafe, activity, 
and fbrength. 
The bones alfo become every day more folid. 
In the embryo they are almoft as foft as the muf- 
cles and the flefh ; but, by degrees, they harden, 
and acquire their natural vigour: but ftill, how- 
ever, the circulation is carried on through them; 
and how hard foever the bones may ieem, the 
blood holds it's current through them, as through 
all other parts of the body. Of this we may be 
fufBciently convinced by an experiment, which was 
firft accidentally difcovered by the late ingenious 
Mr. Belcher. Perceiving, when on a vifit at a 
friend's houfe, that the bones of hogs which were 
fed on madder were red, he tried it on various ani- 
mals, by mixing this plant with their ufual food, 
and found that it tinflured the bones in all: an 
evident demonftration that the juices of the body 
had a circulation through the bones. He fed 
fome animials alternately on madder and their 
common food for fome time, and found their 
bones tinflured with alternate layers, in conformity 
to their manner of living. From all this he na- 
turally concluded, that the blood (as before ob- 
ferved) circulated through the bones, as it does 
through every other part of the body; and that 
how folid foever they feemed, yet, like the fofter 
parts, they were furniflied, through all their fub- 
ftance, with their proper canals. Neverthelefs, 
thefe canals are of very different capacities, during 
the different ftages of exiftence. In infancy, they 
are capacious; and the blood flows through the 
bones with almofL the fame facility as through the 
other channels. In manhood, their fize is greatly 
diminifhed; the velTels are almoft imperceptible, 
and the circulation through them is proportionably 
flow. But, in the decline of life, the blood which 
meanders through the bones no longer contribut- 
ing to their growth, of necefllty tends to increafe 
their rigidity. The channels which are every 
where diffemnnated through the human fratne, may 
be aptly com.pared to thofe pipes that are frequently 
feen internally incrufted by the water running 
through them for a long continuance; both every 
day contraft their diameters, by reafon of the 
fmall rigid particles depofited within them : thus, 
as the vefTels are by degrees diminifhed, the juices 
alfo, neceffary for the circulation through them, 
are diminifhed in proportion ; till at length, in old 
age, thofe pillars of the human fabric are not only 
more folid, but more fragile. 
The cartilages, or griPdes, v/hich may be re- 
garded as foft, imperfect bones, likewife receive 
nutritious juices, which gradually augment their 
denfity : they become more and more Iblid as we 
advance in years; and in old age they are almoft 
as hard as bones themfelves. This rigidity of the 
cartilages renders the motion of the joints ex- 
tremely difficult, and produces a total cefTation of 
external movements. 
As the cartilages becom.e rigid, and unfit the 
joints for motion; fo alfo that mucous liquor, 
which is always feparated between the joints, and 
ferves to give them an eafier and readier play, is 
now furnifhed in lefs and lefs quantities. It be- 
comes thicker and m.ore clammy ; and hence, in 
old age, every joint is not only ftifi', but aukward. 
At every fudden or violent motion, this clammy 
liquor is heard to crack; and it is v/ith difficulty 
that the mufcles overcome it's refiftance. 
The m.embranes v/hich cover the bones, the 
joints, and the reft of the body, as we advance 
in years, become more denfe and dry : thofe 
which furround the bones foon lofe their flexibi- 
lity; and at the age of tv/enty, they are incapable 
of farther extenfion. The m.ufcular fibres fuffer 
a fimilar change, in proportion to the time of 
life; though, to the touch, they feel fofter as age 
increafes : but it is the fkin, and not the mufcles„ 
which occafions this perception. After the body 
is arrived at it's full growth, the fat increafes j 
and, by being interpofed betv/een the fibres of the 
mufcles, and between the fl<in and the mufcles 
themfelves, makes them feel fofter, when in rea- 
lity their denfity is greatly augmented. Of this 
affertion we have an inconteftible proof, by com- 
paring the flefh of young with that of old ani- 
mals: in the former, it is tender and delicate; 
but, in the latter, hard, dry, and unfit for ufe. 
The {\dn is the only part of the body that age 
does not contribute to harden: that ftretches to 
every degree of tenfion ; and we have dreadful 
inftances of it's pliancy in many diforders inci- 
dent to human nature. In youth, therefore, while 
the body is vigorous and increafing, it ftill gives 
way to it's grov/th: but tliough it thus adapts it- 
felf to our increafe, it does not in the fame man- 
ner affimilate itfelf to our decay. The fkin which 
was filled and gloffy in youth, when the body be- 
gins to wafte, does not pofTefs fufficient elaflicity 
to fhrink entirely with it's diminution : it hangs 
therefore in wrinkles, which no art can remove; 
for the wrinkles of the body generally proceed 
from this caufe. But thofe v/rinkles which mark 
the face proceed in general from another caufe ; 
namely, from the variety of pofitions into which 
it is put by the fpeech, the food, and the paf- 
fions. Every grimace, and every paffion, cor- 
rugates the vifage in different forms : thefe are 
fufficiently vifible in youth; but what was at firft 
accidental or tranfient, becomes unalterably fixed 
in the vifage as it grows older. Hence we may 
reafbnably conclude, that an exemption from paf^ 
ficns not only adds to the happinefs of the mind, 
but alfo preferves the beauty of the face; and the 
perfon who has not felt their influence, is lefs 
ftrongly marked by the decays of nature. 
In proportion as we advance in years, the 
bones, the cartilages, the membranes, the flefli, 
the fl<in, and every fibre of the body, become 
more folid, hard, and dry: every part ftirinks, 
every motion becomes more flow; die circulation 
of the fluids is performed with lefs freedom ; per- 
fpiration diminiflics; the fecretions alter; the 
digeftion becomes flow and laborious ; and the 
juices, no longer ferving to convey their accuf- 
tomed nourifliment, thofe parts may be faid to 
live 
