1duſtry truly heroicall and admirable, by Monſignor Maffei Bar
herino, then Prefect for the Wayes, and now Pope. And being
neceſſitated, that I might be able to walk in the Cave, and for
other cauſes, I let down the Sluices of the ſaid Cave, at the mouth
of the Lake: No ſooner were they ſtopt, but a great many of the
people of the Towns and Villages coaſting upon the Lake
flocking thither, began to make grievous complaints, that if thoſe
Sluices were kept ſhut, not onely the Lake would want its due
Vent, but alſo the parts adjacent to the Lake would be over
flown to their very great detriment. And becauſe at firſt appea
rance their motion ſeemed very reaſonable, I found my ſelf hard
put to it, ſeeing no way to perſwade ſuch a multitude, that the
prejudice which they pretended I ſhould do them by keeping
the Sluices ſhut for two dayes, was abſolutely inſenſible; and that
by keeping them open, the Lake did not ebb in the ſame time ſo
much as the thickneſs of a ſheet of Paper: And therefore I was
neceſſitated to make uſe of the authority I had, and ſo followed
my buſineſs as cauſe required, without any regard to that Rab
ble tumultuouſly aſſembled. Now when I am not working with
Mattock or Spade, but with the Pen and Diſcourſe, I intend to
demonſtrate clearly to thoſe that are capable of reaſon, and that
have well underſtood the ground of this my Treatiſe, that the
fear was altogether vain which thoſe people conceited. And
therefore I ſay, that the Emiſſary or Sluice of the Lake of Peru
gia, ſtanding in the ſame mannner as at preſent, and the water
paſſing thorow it with the ſame velocity as now; to examine
how much the Lake may abate in two days ſpace, we ought to
conſider, what proportion the ſuperficies of the whole Lake hath
to the meaſure of the Section of the Emiſſary, and afterwards to
infer, that the velocity of the water by the Emiſſary or Sluice,
ſhall have the ſame proportion to the abatement of the Lake,
and to prove thorowly and clearly this diſcourſe, I intend to
demonſtrate the following Propoſition.
herino, then Prefect for the Wayes, and now Pope. And being
neceſſitated, that I might be able to walk in the Cave, and for
other cauſes, I let down the Sluices of the ſaid Cave, at the mouth
of the Lake: No ſooner were they ſtopt, but a great many of the
people of the Towns and Villages coaſting upon the Lake
flocking thither, began to make grievous complaints, that if thoſe
Sluices were kept ſhut, not onely the Lake would want its due
Vent, but alſo the parts adjacent to the Lake would be over
flown to their very great detriment. And becauſe at firſt appea
rance their motion ſeemed very reaſonable, I found my ſelf hard
put to it, ſeeing no way to perſwade ſuch a multitude, that the
prejudice which they pretended I ſhould do them by keeping
the Sluices ſhut for two dayes, was abſolutely inſenſible; and that
by keeping them open, the Lake did not ebb in the ſame time ſo
much as the thickneſs of a ſheet of Paper: And therefore I was
neceſſitated to make uſe of the authority I had, and ſo followed
my buſineſs as cauſe required, without any regard to that Rab
ble tumultuouſly aſſembled. Now when I am not working with
Mattock or Spade, but with the Pen and Diſcourſe, I intend to
demonſtrate clearly to thoſe that are capable of reaſon, and that
have well underſtood the ground of this my Treatiſe, that the
fear was altogether vain which thoſe people conceited. And
therefore I ſay, that the Emiſſary or Sluice of the Lake of Peru
gia, ſtanding in the ſame mannner as at preſent, and the water
paſſing thorow it with the ſame velocity as now; to examine
how much the Lake may abate in two days ſpace, we ought to
conſider, what proportion the ſuperficies of the whole Lake hath
to the meaſure of the Section of the Emiſſary, and afterwards to
infer, that the velocity of the water by the Emiſſary or Sluice,
ſhall have the ſame proportion to the abatement of the Lake,
and to prove thorowly and clearly this diſcourſe, I intend to
demonſtrate the following Propoſition.
Suppoſe a Veſſel of any bigneſſe, and that it hath an Emiſſary
or Cock, by which it diſchargeth its water. And look what pro
portion the ſuperſicies of the
veſſel hath to the meaſure of
4[Figure 4]
the ſection of the cock, ſuch pro
portion ſhall the velocity of the
Water in the Cock have to the
abatement of the Lake Let the
Veſſel be A B C D, H I L B, through which the Water runneth,
the ſuperficies of the Water in the Veſſel A D, and the ſection
of the Cock H L: and let the Water in the Veſſel
be ſuppoſed to have falne in one determinate time from A to F.
or Cock, by which it diſchargeth its water. And look what pro
portion the ſuperſicies of the
veſſel hath to the meaſure of
4[Figure 4]the ſection of the cock, ſuch pro
portion ſhall the velocity of the
Water in the Cock have to the
abatement of the Lake Let the
Veſſel be A B C D, H I L B, through which the Water runneth,
the ſuperficies of the Water in the Veſſel A D, and the ſection
of the Cock H L: and let the Water in the Veſſel
be ſuppoſed to have falne in one determinate time from A to F.
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