TOU 
Torricelli was then about returning to 
Rome; but the Grand Duke engaged him 
to continue at Florence, making him his 
own mathematician for the present, and 
promising him the professor's chair as soon 
as it should be vacant. Here he applied 
himself intensely to the study of mathema- 
tics, physics, and astronomy, making many 
improvements, and some discoveries. 
Among others, he greatly improved the art 
of making microscopes and telescopes ; and 
it is generally acknowledged that he first 
found out the method of ascertaining the 
"'eight of the atmosphere by a proportionate 
column of quicksilver, the barometer being 
called from him the Torricellian tube, and 
Torricellian experiment. Great things were 
now expected from liim, and great things 
would probably have been further per- 
formed by him, if he had lived; but he 
died, after a few days illness, in 11647, when 
he was but just entered the 40th year of 
his age. His principal work was entitled, 
“ Opera Geometrica,” in 4to. 
1 0RRICELLIAN experiment, a famous 
experiment made by Torricelli, a disciple 
of the great Galileo, which has been alrea- 
dy explained under the article Barome- 
ter. See also Pkeumatics. 
TORRID zone, among geographers, de- 
notes that tract of the earth lying upon the 
equator, and on each side as far as the two 
tropics, or rS° SO’ of north and south lati- 
tude. The torrid zone was believed by the 
ancients to be uninhabitable ; but is now 
well knovyn to be not only inhabited by the 
natives of those hot climates, but even to- 
lerable to the people of the colder climates, 
towards the north and south ; the excessive 
heat of the day being there tempered by 
the coldness of the night. See the article 
Heat. 
TOUCH, or Feeling, sense of. When 
the mind has connected the complex ideas 
derived from the touch with the visible ap- 
pearance of olyects, then the sight is inde- 
finitely the most useful medium of know- 
ledge ; but in the earliest stages of the intel- 
lectual progress, the touch is the most useful ; 
in fact, as man is formed, it then is abso- 
lutely necessary to render the sight pro- 
ductive of most of its present utility. The 
sense of feeling differs from the other senses 
ill belonging to every part of the body, ex- 
ternal or internal, to which nerves are dis- 
tributed. The term touch is most correctly 
applied to the sensibility which is diffused 
over the surface of the body. Touch ex- 
ists with tlie most exquisite degree of sensi- 
T O U 
bility at the extremities of the fingers and 
thumbs, and in the lips. The sense of touch 
is thus very commodiously disposed for the 
purpose of eiicorapassihg smaller bodies, 
and for adapting itself to the inequalities of 
larger ones. 
The sensations acquired by the sense of 
feeling are those of heat, hardness, solidi- 
ty, roughness, dryness, motion, distance, 
figures, &c. and all those corporeal feelings 
which arise from a healthy or diseased state 
of the nerves, and the part of the body to 
which they belong. 
The pains of this sense are more nume- 
rous and vivid than those derived from any 
other sense; and therefore the relicts of 
them coalescing with one another, constitute 
the greatest share of our mental pains, that . 
is, pains not immediately derived from sen- 
sation. On the other hand, its pleasures 
being faint and rare, in comparison with 
others, and particularly those of the taste, 
have but a small share in the formation of 
the mental pleasures. 
The touch is tlie original medium of our 
knowledge respecting the real qualities of . 
substances, and is indeed the sole medium 
by which we gain a knowledge of external 
objects. It is by the touch, and by the touch 
alone, originally, that we distinguish our 
own bodies from other objects that surround 
us, and form the impression which every 
one has, that the objects which affect the 
sight, the hearing, &c. are external. When 
we touch a sensible part of our bodies, 
we have sensations conveyed to the mind 
through two different nervous branches; 
when we touch any other body, we have 
only one sensationj 
The impression that they are external ob- 
jects, that is, objects out of ourselves, which 
give -us the sensations of sound, taste, 
sight, and smell, is so continually forced upon 
us by the sensations of touch, that there pro- 
bably never was found a person who doubt- 
ed the existence of the external world as 
the cause of his sensations, except those 
who have been led to it by reasoning on 
false principles. Some very acute specu- 
lators have indeed given up the belief in 
an external world as the cause of their sen- 
sations; but their opinion never did, nor 
never can, gain much ground ; for it is in- 
consistent with the perceptions, which, by 
the constitution of our frame, are necessa- 
rily formed from continually recurring sen- 
sations. The philosophic Berkeley, and a 
late writer, Drummond, are the principal 
supporters of this curious system. But if 
