Viv 
,e(l. It breeds twice a year, and will occa- 
sionally devour its young as soon as they 
are produced. In confinement it must be 
kept in a box provided with wool, or other 
warm materials, and may be fed with bread 
and milk. Its sleep is long and profound, 
and it awakes with a voracious appetite, 
which is most highly gratified by the blood 
of small and young animals. Its enmity to 
rats and rabbits is unspeakable, and when 
either are, though for the first time, pre- 
sented to it, it seizes and bites them with 
the most phrensied madness. When em- 
ployed to expel the rabbit from its bur- 
rows, it must be muzzled, as otherwise it 
will suck the blood of its victim, and in- 
stantly fall into a profound sleep, from which 
it will awake only to the work of destruc- 
tion, committing in the warren, w'here it 
was introduced only for its services, the 
most dreadful waste and havoc. It is pos- 
sessed of high irritability, and when parti- 
cularly excited, is attended with an odour 
extremely offensive. See Mammalia, Plate 
XVI. fig. 4. 
V. vulgaris, or the common weasel, is 
about nine inches long, including the tail, 
is elegant in its appearance, and light in its 
movements, but unpleasant by the odour 
which accompanies it. It dwells under the 
roots of trees, and subsists on field mice, 
small birds, and even young rabbits. It is 
also particularly fond of eggs. It is often 
fatal to the hare itself, which appears to en- 
tertain for the weasel extreme terror, and to 
be overwhelmed at the sight of it into a com- 
plete incapacity for resistance. It is a more 
formidable enemy to rats and mice than 
even the cat itself, as it has greater facility 
for pursuing them to their retreats, and on 
this account it is much valued and encourag- 
ed by the farmer. Its bite is said to be almost 
certainly, though not always immediately, 
fatal. Its teeth are extremely sharp, and 
generally first fixed on the head of its ene- 
my, which often lingers in stupor, but 
scarcely ever regains soundness. It com- 
mences its depredations in the evening, and, 
when it has produced its young, ranges with 
extreme intrepidity and rapacity. It is 
frequent near corn-mills, and wherever rats 
and mice are abundant, and always retires 
with its prey to its burrow, instead of de- 
vouring it on the spot where it was kilted, 
preferring it in a state of putrefaction. Dur- 
ing confinement it appears highly agitated 
and restless, and has by many been sup- 
posed untameable, but Madamoiselle de 
Juaistre has given an interesting and full de< 
VIV 
tail of the manners of one which she under- 
took to protect and instruct, and which re- 
paid her assiduity by the most sportive vi- 
vacity, the most harmless conduct, and even 
the most grateful attachment. For the stoat, 
see Mammalia, Plate XVL fig. 3. Vol. iv. 
VIVIANI (ViNCENTio), a celebrated Ita- 
lian mathematician, was born at Florence 
in 1621, some say 1622. He was a disciple 
of the illustrious Galileo, and lived with 
him from the 17 th,to the 20th year of his 
age. After the death of his great master, 
lie passed two or three years more in pro- 
secuting geometrical studies without inter- 
ruption, and hi this time it was that he 
formed the design of his Restoration of 
Aristeus. Tliis ancient geometrician, who 
was contemporary with Euclid, bad com- 
posed five hooks of problems, “ De Loci* 
Solidis,” the bare propositions of which 
were collected by Pappus, but the books 
are entirely lost ; which Viviaiii undertook 
to restore by the force of his genius. 
He broke this work otf before it was 
finished, in order to apply himself to ano- 
tlier of the same kind, which was, to restore 
the fifth book of Apollonius’s “ Conic Sec- 
tions.” While he was engaged in this, Bo- 
relli found, in the library of the Grand 
Duke of Tuscany, an Arabic M.S. with a 
Latin inscription, importing that it con- 
tained the eight books of Apollonius’s Co- 
nic Sections ; of which the eighth was not 
found to be there. He carried this M.S. 
to Rome, in order to translate it with the 
assistance of a professor of the oriental lan- 
guages. So unwilling however was Viviani 
to lose the fruits of his labours, that he re- 
fused to receive the smallest account from 
Borelli on the subject. At length he finish- 
ed the work, and published it in 1659, with 
the title “ De Maximis et Minimis geome- 
trica divinatio in quiiitum conicoriim Apol- 
lonii Pergaei. He was called by tlie state 
to undertake an operation of great import- 
ance, viz. to prevent the inundations of the 
Tiber, in which Cassini and he were em- 
ployed for some length of time. On account 
of his great talents he received a pension 
from Louis XIV. In 1666 he was honoured 
by the Grand Duke with the title of the 
first mathematician. He resolved three pro- 
blems which had been proposed to all the 
mathematicians of Europe. In 1669 he was 
chosen to till, in the Royal Academy of 
Sciences, a place among the eight foreign 
associates. This circumstance, so honour- 
able to his reputation, gave new vigour to 
his exertions, and he published three books 
