PAS 
asked him then how he came to think of 
this : it was, said Blaise, because 1 found 
out such another thing ; and so, going back- 
ward, and using the names of bar and round, 
he came at length to the definitions and 
axioms he had formed to himself. From 
this time he had full liberty to indulge his 
genius in mathematical pursuits. He un- 
derstood Euclid’s Elements as soon as 
he cast his eyes upon them. At sixteen 
years of age he W'rote a treatise on Conic 
Sections, which was accounted a great 
effort of genius ; and therefore it is no 
wonder that Des Cartes, who had been in 
Holland a long time, upon reading it, should 
choose to believe that M. Pascal the father 
was the real author of it. At nineteen 
he contrived an admirable arithmetical 
machine, which would have done credit as 
an invention to any man versed in science. 
About this time his health became impair- 
ed, so that he was obliged to suspend his 
labours for the space of four years. After 
this, having seen Torricelli’s experiment 
respecting a vacuum and the weight of the 
air, he turned his thoughts towards these 
objects, and undertook several new experi- 
ments, by which he was fully convinced of 
the general pressure of the atmosphere; 
and from this discovery he drew many use- 
ful and important inferences. He com- 
posed also a large treatise, in which he fully 
explained this subject, and replied to all 
the objections that had been started against 
it. As he afterwards thought this work 
rather too prolix, and being fond of brevity 
and precision, he divided it into two small 
treatises, one of winch he entitled, “A Dis- 
sertation on the Equilibrium of Fluids;” 
and the other, “ An Essay on the Weight 
of the Atmosphere.” These labours pro- 
cured Pascal so much reputation, that the 
greatest mathematicians and philosophers 
of the age proposed various questions to 
him, and consulted him respecting such dif- 
ficulties as they could not resolve. Upon 
one of these occasions he discovered the 
solution of a problem proposed by Mer- 
senne, which had baffled the penetration of 
all that had attempted it. This problem 
was to determine the curve described in 
the air by the nail of a coach wheel, while 
the machine is in motion ; which curve was 
thence called a roullette, but now commonly 
known by the name of cycloid. Pascal 
offered a reward of forty pistoles to any one 
who should give a satisfactory answer to it. 
No person having succeeded, he published 
his own at Paris; but- under the name of 
PAS 
A. d’Ettonville. This was the last work 
which he published in the mathematics ; 
his infirmities, from a delicate consitution, 
though still young, now increasing so much, 
that he was under the necessity of renounc- 
ing severe study, and of living so recluse, 
that he scarcely admitted any person to 
see him. 
After having thus laboured abundantly 
in mathematical and philosophical disquisi- 
tions, he forsook those studies and all human 
learning at once, to devote himself to acts 
of devotion and penance. He was not 
twenty-four years of age, when the reading 
some pious books had put him upon taking 
this resolution ; and he became as great a 
devotee as any age has produced. He now' 
gave himself up entirely to a state of prayer 
and mortification; and he had always in his 
thoughts these great maxims of renouncing 
alt pleasure and all superfluity ; and this he 
practised with rigour even in' his illnesses, 
to which he was frequently subject, being 
of a very invalid habit of body. He died 
at the age of thirty-nine. His works were 
collated and published at the Hague in 
five volumes 8vo, by the Abbe Bossu, 1779. 
Pascal rents, rents or annual duties 
paid by the inferior .clergy to the bishop or 
archdeacon, at their Easter visitation. 
PASPALUM, in botany, a genus of the 
Triandria Digynia class and order. Natu- 
ral order of Gramina, Gramine®, or Grasses. 
Essential character : calyx two-valved, or- 
bicular ; corolla of the same size ; stigmas 
pencilled. There are fifteen species. All 
these grasses are of foreign growth, none of 
them natives of Europe. 
PASSAGE. In stat. 4 Edward HI, c. 7, 
this term is used for the hire a man pays for 
being transported over any sea' or river. 
■Various statutes of a local nature have been 
passed for regulating the passage of parti- 
cular rivers. By a statute of Edward IV. 
the passage from Kent to Calais is restrained 
to Dover. 
Passage, birds of, a name given to 
those birds which at certain stated seasons 
of the year remove fl-om certain countries, 
and at other stated times return to them 
again, as our quails, woodcocks, storks, 
nightingales, swallows, and many other spe- 
cies. The generality of birds that remain 
with us all the winter have strong bills, and 
are enabled to feed on what they can find 
at that season ; those which leave ns, have 
usually very slender bills, and their food is 
the insects of the fly kind, which disap- 
pearing towards the approach of winter. 
