1804.) 
any other apparatus than is at hand to 
évery one. It is not in our power to fol- 
low Dr. Young in his calculations and in- 
ductions, but we lay before the reader 
what he calls an argumentative inference 
refpecting the natuie of light, 
‘‘From the experiments and calcula- 
tions (lays he) which have been pre- 
mifed, we may be allowed to infer, that 
homogeneous light, at certain equal dif- 
tances in the direction of its motion, is 
poflefled of oppofite qualities, capable of 
neutralizing and deftroying each other; 
and of extinguifhing the light, where 
they happen to be united; that thefe 
qualities fucceed each other alternately 
in fucceflive concentric fuperficies, at 
diftances which are conftant, for the 
fame light, paffing through the fame 
medium. From the agreement of the 
meafures, and from the fimilarity of the 
phenomena, we may conclude that thefe 
intervals are the fame as are concerned in 
the production of the colours of thin plates ; 
but thefe are fhown, by the experiments of 
Newton, to be the fmaller the denfer the 
medium ; and fince it may neceflarily be 
prefumed that their number mutt remain 
unaltered in a given quantity of light, it 
follows of courfe, that light moves more 
flowly in a denfer than in ararer medium; 
and this being granted, it muft be allowed 
that refraction is not the effeét of an at- 
tractive force direéted to a denfer medium. 
The advocates for the projectile hy pothefis 
of light, muft confider which link in this 
chain of reafoning they may judge to be 
the moft feeble; for, hithert:, I have 
advanced, in this paper, no general hy- 
pothelis whatever, But fince we know 
that found diverges in cuncentric fuper- 
ficies, and that mufical founds confilt of 
Oppolite qualities capable of neutralizing 
each other, and fueceeding at certain equal 
intervals, which are different according 
to the difference of the note, we are fully 
authorized to conclude, that there mutt 
be fome {trong refemblance between the 
nature of found and that of light.” 
Mr. ANTHONY CARLISLE prefented 
to this fociety in the year 1800, through 
the medium of his friend Mr. Symmons, 
an account of a peculiarity in the diftri- 
bution of the arteries fent to the limbs of 
flow-moving animals. Since that time 
he has endeavoured to colleét farther il- 
Juftrations to fhow the connection between 
the difpofition of the blood-veffels and the 
aétions. of the mufcles. He imagines that 
the rete mirabile, in ruminating and car- 
niverous animals, is a contrivance intended 
to relirain that velocity of the blood which 
Proceedings of Learned Societies. 
257 
their habits and figures would otherwife 
produce, in its paflage to the brain. 
The circuitous courfe of all the arteries 
which fupply the human brain, and their 
confinement in long paflages, is obvioufly 
tor a fimilar purpofe. 
In feeking for examples in other direc- 
tions, he found in the human body two 
fmall arteries arife from the upper part'of 
the abdominal aorta; and, in men, they 
defcend from thence to the tefticles. They 
are called the {permatic arteries, and are 
the longeft arterial cylinders in the 
body. ‘The next in refembiance are the 
intercoftal arteries, and, laftly, thofe of 
ihe diaphragm. 
The iris in man, and in animals, 1s fure 
nifhed with cylindrical arteries, which 
pierce the pofterior part of the globe of 
the eye, and finally enter that mufcle by 
a circuitous courfe. The pupil of the 
eye contracts flowly, and 1s occafionally 
required to continue long in that ftate.—.. 
The inftance of an oppofite- mode of diftri. 
bution is to be found in the coronary arte- 
ries which fupply the heart, a mutcle 
whofe agtions are more rapid than thofe 
of any other; at the fame time it is ob- 
fervable, that the coronary aricries are 
mere quickly fab-divided than the arte. 
ries of mufcles generally. The alteration 
which the blood undergoes during the fup. 
ply of this mufcle only is, that the coro= 
nary veins return venous blood apparently 
as much changed from the arterial {tae as 
if it had pafled through the remoteft ors 
gans of the body 
Any impediment to the accuftomed 
courle of the blood flov ing through mu 
cles, induces a corre!pconding diminution 
in their powers of aétion. Wien the prin- 
cipal arterialtrunk which fupplies the mufé 
cles of the leg is obliterated by ligature, 
for the cure of an aneurifm, the leg re- 
mains weakened in its mufcular ttrength, 
until the circuitous veffels have again ré- 
ftored a vigorous fupply of blood. 
Animals with prehenfile tails, fuch as 
certain monkeys and opoffums, have the 
mulfcles of their tails fupplied by one cy- 
lindrical artery ; and the length of time 
they can {ufpend themfelves by their tails 
is remarkable, notwithitanding the afift- 
ance derived from the repetition,of coils 
around the boagh of atree, and cccalion- 
ally from an elaftic bend in the extreme 
joint of fome prehenfile tails. 
The fwimming-bladders of fome fifhes 
afford another example of cylindrical are 
teries {upplying the mufcular parts of 
them. As thele bladders appear deitined 
to affilt the fifh in rifing or defcending in 
water, 
