1order to break the Fury of the Waves, that
not finding any Thing to beat againſt
with their whole Strength, they may fall back
gently and not with too violent a Precipitation.
Thus the Wave which is upon Return will
meet that which is coming on, and deaden its
Force. The Mouths of Rivers ſeem to be of
the ſame Nature with the Port, as they afford
Shelter to Veſſels againſt Storms. They ought
therefore to be fortified and made narrower to
exclude the Fury of the Sea. Propertius ſays,
not finding any Thing to beat againſt
with their whole Strength, they may fall back
gently and not with too violent a Precipitation.
Thus the Wave which is upon Return will
meet that which is coming on, and deaden its
Force. The Mouths of Rivers ſeem to be of
the ſame Nature with the Port, as they afford
Shelter to Veſſels againſt Storms. They ought
therefore to be fortified and made narrower to
exclude the Fury of the Sea. Propertius ſays,
IT is the ſame in this Caſe; for the Mouths
of Rivers by the inceſſant Attacks of the Sea
are either overcome and filled up with Sand;
or elſe by a conſtant and obſtinate Reſiſtance,
they conquer and keep their Paſſages clear.
For this Reaſon it is an admirable Method to
open the River a double Diſcharge into the
Sea by two different Branches, if you have but
Water enough to ſupply them; not only that
Ships may be able to get in at one of them,
though the Wind be contrary for the other;
but alſo that if one of them be ſtopt up, either
by ſome Storm at Sea, or by ſome ſtrong
Wind blowing into it, in ſuch a Manner that
the Land-floods would be driven back again
into the Country, they may have another Paſſ
age open to diſcharge themſelves into the Sea.
But of this enough. The next Point is how
to clean a River. Cæſar took a great deal of
Care about cleaning the Tyber, which was ſtopt
up with Rubbiſh, and there are vaſt Heaps of
the Stuff that was taken out ſtill to be ſeen not
far from the River, as well within the City as
without. By what Methods he got ſo much
Rubbiſh out of ſo ſwift a River, I do not re
member to have read: But I ſuppoſe he made
uſe of Frames to ſhut out the River and then
emptying the Water out of them, he might
eaſily take out the Rubbiſh. Theſe Frames
are made in the following Manner: Prepare
ſome ſtrong Timbers cut ſquare, with Grooves
cut in the Sides of them from Top to Bottom
four Inches deep, and in Breadth equal to the
Thickneſs of the Planks which you intend to
uſe in this Work; and prepare your Planks al
ſo of equal Length and Thickneſs with one
another. Having got theſe Things ready,
drive down your Timbers ſo as they may ſtand
perpendicular, at Diſtances from each other
equal to the Length of your Planks. When
your Timbers are well fixed, let your Planks
into the Grooves and drive them down to the
Bottom. Our Workmen call theſe Frames
Cataracts. Go on in the ſame Manner to fill
up the Spaces between the Timbers with Planks
and drive them as cloſe together as poſſible.
Then go to work immediately with your
Pumps, Syphons, Buckets and all your other
Implements for emptying out the Water, put
ting on as many Hands as you can, and labour
ing without Intermiſſion till you have thrown
out all the Water within your Incloſure. If it
leaks in any Part, ſtop up the Crack with any
old Rags: And thus the Buſineſs may be done.
Between this Frame and that which we men
tioned as neceſſary in the Building of Bridges,
there is this Difference; that the latter muſt be
ſtable and laſting, being to ſtand not only till
the Piers are built, but even till the Super
ſtructure is ſettled; whereas this is only tem
porary, and as ſoon as the Dirt is got out to be
preſently removed to another Place. But I
adviſe you, whether you clean your River by
the Help of this Frame, or by turning the
Courſe of the Water, that you do not pretend
to ſtrive againſt the whole Force of the Stream
at a Time in any one Place, but go on Step by
Step and by Degrees. All Works raiſed againſt
the Violence of Waters, if they are made in
the Form of Arches, with their Backs turned
againſt the Weight of the Water, they will be
able to make the ſtouter Reſiſtance. You may
level a Torrent or Water-fall by laying a Bar
rier acroſs the Stream in ſuch a Manner that the
Water is obliged to riſe a good deal higher
than uſual: For the Water running over from
the Top of this Barrier, will dig up the Ridge
in the Channel by its fall; and then even the
Channel above the Torrent, quite to the Spring
will be levelled in Proportion to the lower
Part of the Channel; for the Water in its De
ſcent will be continually moving and carrying
away the Earth. You may clean your Chan
nel by turning Oxen into it in the following
Manner: Stop it up that the Water may ſwell;
then drive your Cattle about in it ſo that they
may diſturb all the Mud, and then opening the
Stream that the Water may pour in rapidly, it
will waſh and carry away all the Dirt. If any
thing lies buried and fixed in the Stream ſo as
to ſpoil the Navigation, beſides the common
Machines uſed by Workmen for removing ſuch
Obſtructions, it is a very good Method to load
a Barge deep, and to it faſten with Ropes the
Impediment which you would pull up: Then
of Rivers by the inceſſant Attacks of the Sea
are either overcome and filled up with Sand;
or elſe by a conſtant and obſtinate Reſiſtance,
they conquer and keep their Paſſages clear.
For this Reaſon it is an admirable Method to
open the River a double Diſcharge into the
Sea by two different Branches, if you have but
Water enough to ſupply them; not only that
Ships may be able to get in at one of them,
though the Wind be contrary for the other;
but alſo that if one of them be ſtopt up, either
by ſome Storm at Sea, or by ſome ſtrong
Wind blowing into it, in ſuch a Manner that
the Land-floods would be driven back again
into the Country, they may have another Paſſ
age open to diſcharge themſelves into the Sea.
But of this enough. The next Point is how
to clean a River. Cæſar took a great deal of
Care about cleaning the Tyber, which was ſtopt
up with Rubbiſh, and there are vaſt Heaps of
the Stuff that was taken out ſtill to be ſeen not
far from the River, as well within the City as
without. By what Methods he got ſo much
Rubbiſh out of ſo ſwift a River, I do not re
member to have read: But I ſuppoſe he made
uſe of Frames to ſhut out the River and then
emptying the Water out of them, he might
eaſily take out the Rubbiſh. Theſe Frames
are made in the following Manner: Prepare
ſome ſtrong Timbers cut ſquare, with Grooves
cut in the Sides of them from Top to Bottom
four Inches deep, and in Breadth equal to the
Thickneſs of the Planks which you intend to
uſe in this Work; and prepare your Planks al
ſo of equal Length and Thickneſs with one
another. Having got theſe Things ready,
drive down your Timbers ſo as they may ſtand
perpendicular, at Diſtances from each other
equal to the Length of your Planks. When
your Timbers are well fixed, let your Planks
into the Grooves and drive them down to the
Bottom. Our Workmen call theſe Frames
Cataracts. Go on in the ſame Manner to fill
up the Spaces between the Timbers with Planks
and drive them as cloſe together as poſſible.
Then go to work immediately with your
Pumps, Syphons, Buckets and all your other
Implements for emptying out the Water, put
ting on as many Hands as you can, and labour
ing without Intermiſſion till you have thrown
out all the Water within your Incloſure. If it
leaks in any Part, ſtop up the Crack with any
old Rags: And thus the Buſineſs may be done.
Between this Frame and that which we men
tioned as neceſſary in the Building of Bridges,
there is this Difference; that the latter muſt be
ſtable and laſting, being to ſtand not only till
the Piers are built, but even till the Super
ſtructure is ſettled; whereas this is only tem
porary, and as ſoon as the Dirt is got out to be
preſently removed to another Place. But I
adviſe you, whether you clean your River by
the Help of this Frame, or by turning the
Courſe of the Water, that you do not pretend
to ſtrive againſt the whole Force of the Stream
at a Time in any one Place, but go on Step by
Step and by Degrees. All Works raiſed againſt
the Violence of Waters, if they are made in
the Form of Arches, with their Backs turned
againſt the Weight of the Water, they will be
able to make the ſtouter Reſiſtance. You may
level a Torrent or Water-fall by laying a Bar
rier acroſs the Stream in ſuch a Manner that the
Water is obliged to riſe a good deal higher
than uſual: For the Water running over from
the Top of this Barrier, will dig up the Ridge
in the Channel by its fall; and then even the
Channel above the Torrent, quite to the Spring
will be levelled in Proportion to the lower
Part of the Channel; for the Water in its De
ſcent will be continually moving and carrying
away the Earth. You may clean your Chan
nel by turning Oxen into it in the following
Manner: Stop it up that the Water may ſwell;
then drive your Cattle about in it ſo that they
may diſturb all the Mud, and then opening the
Stream that the Water may pour in rapidly, it
will waſh and carry away all the Dirt. If any
thing lies buried and fixed in the Stream ſo as
to ſpoil the Navigation, beſides the common
Machines uſed by Workmen for removing ſuch
Obſtructions, it is a very good Method to load
a Barge deep, and to it faſten with Ropes the
Impediment which you would pull up: Then