Capias ad audiendum judicium, is a writ which 
issues against one who has been found guilty of 
a misdemeanor, to bring him in to receive his 
judgment; and if he absconds, he may be prose- 
cuted, even to outlawry. 
CAPILLARIES. The innumerable, minute, 
and terminational ramifications of the arteries, in 
the circulating system of red-blooded animals. 
They derive their name from the circumstance 
of their being so slender and fine as to resemble 
hairs; but they actually become so minute as to 
be invisible, and are so multitudinously ramified 
that some one or more of them are wounded by 
| the slightest puncture. These countless and 
wonderfully minute vessels make all the deposi- 
tions of nourishment and secretion which the ar- 
terial blood conveys to the several parts of all 
the members of the body; and hence, when they 
| begin to unite, to enlarge, and to connect them- 
| selves with the veins, they deliver black or ve- 
' nous blood, instead of the red or arterial blood 
_ which they had received. The capillaries are 
| thus the seat of secretion and the link between 
| the arteries and the veins; but. the points at 
which they lose their arterial character, and 
| assume their venous one, are too recondite and 
| microscopic to be capable of observation. 
CAPILLARY ATTRACTION. A term of fre- 
quent occurrence in physics, signifying properly 
that force by which water, mercury, or any other 
fluid, is raised above its level in tubes whose 
| diameter does not exceed that of a hair, hence 
called capillary tubes. It is now employed, in a 
| more general sense, to denote that force with 
which solids act upon fluids, either in raising 
them above, or depressing them below, their na- 
tural level, when the solid is simply immersed in 
| the fluid, or when the fluid is included in a tube, 
| or between two plates formed from the solid. In 
attempting to give as complete a view of this 
interesting portion of physics as the limits of our 
work will permit, we shall direct our readers’ 
attention to the different phenomena of capillary 
attraction, as they have been ascertained by 
direct experiment, and to the different theories 
by which these phenomena have been explained. 
EEE EE EE eee ee 
| Exp. 1. If water, or any other fluid, excepting 
mercury and the metals in a fluid state, be poured 
into a clean vessel, the fuid in contact with the sides 
|| of the vessel will be raised above the level of the 
| fluid in the middle of the vessel, and the fluid surface 
will be terminated by an elevated ring of fluid. See 
Plate XV., Fig. 1, where A, B are the sides of the 
vessel, and c, d, the elevated fluid. 
Exp. 2. Vf a solid body is immersed in a fluid, the 
fluid will be raised round the sides of the solid, as 
i ae 2, where S is the solid, and c d the elevated 
uid, 
_ Exp. 3. If the fluid, used in experiments 1 and 2, 
1s mercury, or any metal in a state of fusion, the fluid 
in contact with the sides of the vessel in Exp. 1, or 
with the sides of the solid body in Exp. 2, will be 
depressed below the general level, as is exhibited in 
Figs. 3d and 4th. 
Exp. 4. Ifa glass tube A, Fig. 5, whose internal 
diameter or bore is less than the 10th of an inch, be 
| tube. 
683 | 
immersed at one end into a fluid in the vessel MN, 
the fluid will rise to A to a considerable height above 
the fluid surface. If another capillary tube B of a 
greater bore is immersed in the same fluid, the fluid 
will also rise in the tube above its level, but not to 
such a height as in the tube A. By comparing the 
heights of the fluid in the two tubes, with the dia- 
meters of their bores, it is found that the heights are 
inversely as the diameters. 
Exp. 5. If the preceding experiment is tried with 
fluids of different kinds, it will be found that they 
rise to different altitudes. 
Exp. 6. If tubes of different lengths are employed, | 
the fluid will never ascend to the top of the tube, 
however short. Thus in Fig. 5, if the tube AC is 
broken off at P, the fluid will stand at p below the 
top P, though it formerly rose as high as A. 
Exp. 7. Vf a capillary tube, composed of two cy- 
linders of different bores, be immersed in a fluid first 
with the widest part downwards, as at E, Fig. 5, 
and afterwards with the narrowest part downwards, 
as at F, Fig. 5, the fluid will ascend in both cases to 
the same height. 
Exp. 8. When the widest part of the tube is not 
capillary, but is of such a magnitude that the fluid 
will not rise spontaneously to the smaller part, let 
the wider part be filled by suction, and the fluid will 
stand at the same height in the smaller part of the 
tube, as it would have done had the whole tube been 
of the same bore with the capillary part. 
Exp. 9. If the tube, when filled by suction, as in 
the preceding experiment, be placed in the receiver 
of an air-pump. and the air exhausted, the fluid in 
the wider part of the tube will not remain suspended 
in the tube as formerly, but will fall down into the 
vessel. 
Exp. 10. If one tube is placed within another so 
that their axes coincide, the water will rise in the 
space between the tubes only to half the height that 
it would have done in a single tube, in which the di- 
ameter of the bore is equal to the interval between | 
the two tubes. 
CAPILLARY ATTRACTION. 
NRE ES ICC SE ET 8 AI EA OS AT 
| 
Exp. 11. When the internal diameter of several 
capillary tubes are equal, the fluid will rise to the 
same height whether the tubes are thin or thick. 
Exp. 12. Having plunged a capillary tube into wa- 
ter, let the lower extremity of it be closed with the | 
finger, and when the tube is taken out of the water, 
let its external surface be gently wiped. Upon with- 
drawing the finger, the water is seen to subside in 
the tube and form a drop at its lower base; but the 
height of the column is always greater than the ele- 
vation of the water in the tube, in the common ex- | 
periment of plunging it in water. It has also been 
observed, that the increase in the elevation of the 
water is more considerable, the smaller the diameter 
of the drop beneath. 
Exp. 13. Ifa drop of water is introduced into a 
conical capillary tube, open at both ends, and held in 
a horizontal position, it will move towards the vertex 
of the cone. 
Exp. 14. When water is forced through a capillary 
tube, of such a bore that it is discharged only in 
successive drops, it will flow in a constant and acce- | 
lerated stream when the tube is electrified, and the | 
acceleration will be inversely proportional to the di- | 
ameter of the bore. 
Exp. 15. A capillary syphon which discharges 
cold water only by drops, will discharge water of a | 
higher temperature in a continued stream. | 
Exp. 16. Let a capillary tube be held in a position | 
inclined to the horizon, and let a drop of liquid be | 
let fall upon its surface, then bringing the tube into | 
a vertical position at the instant when the drop has 
arrived at the inferior orifice, the fluid will run 
through the orifice, and rise in the interior of the 
