1it was manifeſt that the riſing of the Lake cauſed by the rain, was
to a hair thoſe four fingers breadth that I had judged it to be.
Two dayes after I had another bout with the Ingeneer, and re
lated to him the whole buſineſs, to which he knew not what to
anſwer.
to a hair thoſe four fingers breadth that I had judged it to be.
Two dayes after I had another bout with the Ingeneer, and re
lated to him the whole buſineſs, to which he knew not what to
anſwer.
Now the two difficulties which I thought of, able to impede
my concluſion, were theſe following: Firſt, I conſidered that
it might be, that the Wind blowing from the ſide where the
Sluice ſtood, to the Lake-ward; the mole and maſs of the Wa
ter of the Lake might be driven to the contrary ſhore; on which
the Water riſing, it might be fallen at the mouth of the Emiſſa
ry, and ſo the obſervation might be much obſcured. But this
difficulty wholly vaniſhed by reaſon of the Aires great tranqui
lity; which it kept at that time, for no Wind was ſtirring on any
ſide, neither whilſt it rained, nor afterwards.
my concluſion, were theſe following: Firſt, I conſidered that
it might be, that the Wind blowing from the ſide where the
Sluice ſtood, to the Lake-ward; the mole and maſs of the Wa
ter of the Lake might be driven to the contrary ſhore; on which
the Water riſing, it might be fallen at the mouth of the Emiſſa
ry, and ſo the obſervation might be much obſcured. But this
difficulty wholly vaniſhed by reaſon of the Aires great tranqui
lity; which it kept at that time, for no Wind was ſtirring on any
ſide, neither whilſt it rained, nor afterwards.
The ſecond difficulty which put the riſing in doubt, was, That
having obſerved in Florence, and elſewhere, thoſe Ponds into
which the rain-water, falling from the houſe, is conveyed
through the Common-ſhores: And that they are not thereby
ever filled, but that they ſwallow all that abundance of water,
that runs into them by thoſe conveyances which ſerve them with
water; inſomuch that thoſe conveyances which in time of
drought maintain the Pond, when there comes new abundance
of water into the Pond, they drink it up, and ſwallow it: A like
effect might alſo fall out in the Lake, in which there being many
veins (as it is very likely) that maintain and feed the Lake; theſe
veins might imbibe the new addition of the Rain-water, and ſo
by that means annuall the riſing; or elſe diminiſh it in ſuch ſort, as
to render it inobſervable. But this difficulty was eaſily reſolved
by conſidering my Treatiſe of the meaſure of Running-Waters;
foraſmuch as having demonſtrated, that the abatement of a Lake
beareth the reciprocal proportion to the velocity of the Emiſſa
ry, which the meaſure of the Section of the Emiſſary of the Lake,
hath to the meaſure of the ſurface of the Lake: making the
calculation and account, though in groſs; by ſuppoſing that its
veins were ſufficiently large, and that the velocity in them were
notable in drinking up the water of the Lake; yet I found never
theleſs, that many weeks and moneths would be ſpent in drink
ing up the new-come abundance of water by the rain, ſo that
I reſted ſure, that the riſing would enſue, as in effect it did.
having obſerved in Florence, and elſewhere, thoſe Ponds into
which the rain-water, falling from the houſe, is conveyed
through the Common-ſhores: And that they are not thereby
ever filled, but that they ſwallow all that abundance of water,
that runs into them by thoſe conveyances which ſerve them with
water; inſomuch that thoſe conveyances which in time of
drought maintain the Pond, when there comes new abundance
of water into the Pond, they drink it up, and ſwallow it: A like
effect might alſo fall out in the Lake, in which there being many
veins (as it is very likely) that maintain and feed the Lake; theſe
veins might imbibe the new addition of the Rain-water, and ſo
by that means annuall the riſing; or elſe diminiſh it in ſuch ſort, as
to render it inobſervable. But this difficulty was eaſily reſolved
by conſidering my Treatiſe of the meaſure of Running-Waters;
foraſmuch as having demonſtrated, that the abatement of a Lake
beareth the reciprocal proportion to the velocity of the Emiſſa
ry, which the meaſure of the Section of the Emiſſary of the Lake,
hath to the meaſure of the ſurface of the Lake: making the
calculation and account, though in groſs; by ſuppoſing that its
veins were ſufficiently large, and that the velocity in them were
notable in drinking up the water of the Lake; yet I found never
theleſs, that many weeks and moneths would be ſpent in drink
ing up the new-come abundance of water by the rain, ſo that
I reſted ſure, that the riſing would enſue, as in effect it did.
And becauſe many of accurate judgement, have again cauſed
me to queſtion this riſing, ſetting before me, that the Earth be
ing parched by the great drought, that had ſo long continued, it
might be, that that Bank of Earth which environed the brink of
the Lake, being dry, and imbibing great abundance of Water
me to queſtion this riſing, ſetting before me, that the Earth be
ing parched by the great drought, that had ſo long continued, it
might be, that that Bank of Earth which environed the brink of
the Lake, being dry, and imbibing great abundance of Water