This does not seem right to me:

History Chanel Modern Marvels
Season 10, Episode 15

Hydraulics

8 minutes into the episode:

[Narrator voice Lloyd Sherr (stage name Max Raphael] "By 30 B.C. The
Roman empire... the aqueduct"

[Prof. Thanos Papanicolaou IIHR University of Iowa] "The Romans they
realized they had to feed bigger areas then they had to have a system
where they can carry large quantities and same time use the concept of
gravity."

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

" fired this volley in
:

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

As typically done by video journalists, they mix, mish, and mash techno-
babble until they come up with something that sounds "good", then go with
it.

Let's say they fetched the water from a mountain lake. If the lake were
3000' above the point of use, then the total available water column
pressure would be 1300psi. Now, of course, it's "open", and not held in
a closed column. So, in fact, the pressure is 0 psig at any point along
the aquaduct. But the _available_ column pressure is 1300psi, 3000' below
the source, if enclosed.

Simple, typical, journalistic, wrong-headed interpretation of physics.

LLoyd

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote

Let's say they fetched the water from a mountain lake. If the lake were
3000' above the point of use, then the total available water column
pressure would be 1300psi. Now, of course, it's "open", and not held in
a closed column. So, in fact, the pressure is 0 psig at any point along
the aquaduct. But the _available_ column pressure is 1300psi, 3000' below
the source, if enclosed.

Simple, typical, journalistic, wrong-headed interpretation of physics.

LLoyd

Actually, water is .443 psi per foot, salt water .445 psi. This is derived
from taking 14.7 psi per every 33 foot of depth when scuba diving. So,
actually, the lake would be 2,934 feet higher, but your figure is close
enough.

HTH

Steve ;-)

On May 24, 9:27*am, "Steve B" wrote:

Actually, water is .443 psi per foot, salt water .445 psi. *This is derived
from taking 14.7 psi per every 33 foot of depth when scuba diving. *So,
actually, the lake would be 2,934 feet higher, but your figure is close
enough.

HTH

Steve ;-)

You can not take a constant with three significant digits and use it
to get an answer with four significant digits.This is true of your
answer and of Dave_67.

Dan

On May 24, 9:34*am, " wrote:
On May 24, 9:27*am, "Steve B" wrote:

Actually, water is .443 psi per foot, salt water .445 psi. *This is derived
from taking 14.7 psi per every 33 foot of depth when scuba diving. *So,
actually, the lake would be 2,934 feet higher, but your figure is close
enough.

HTH

Steve ;-)

You can not take a constant with three significant digits and use it
to get an answer with four significant digits.This is true of your
answer and of Dave_67.

* * * * * * * * * * * * * * * * * * * * * * * * *Dan

Oh, don't get me going on significant figures. I care about 'em when I
need to, ancient roman plumbing isn't one of those times!


Dave

Dave__67 wrote:
On May 24, 9:34*am, " wrote:
On May 24, 9:27*am, "Steve B" wrote:

Actually, water is .443 psi per foot, salt water .445 psi. *This is
derived from taking 14.7 psi per every 33 foot of depth when scuba
diving. *So, actually, the lake would be 2,934 feet higher, but your
figure is close enough.

You can not take a constant with three significant digits and use it
to get an answer with four significant digits.This is true of your
answer and of Dave_67.

Oh, don't get me going on significant figures. I care about 'em when I
need to, ancient roman plumbing isn't one of those times!

Well, they built aquaeducts some miles long (hundreds?) and matched the
pipes/chutes up to within a fraction of an inch to one another. They
had to have had _something_!

And there's the problem of the pyramids - could it be true that they were
designed by Atlantean architects and built by Lemurian slaves who still
had the power of levitation by sound vibrations?

Thanks,
Rich

On May 24, 9:34*am, " wrote:
On May 24, 9:27*am, "Steve B" wrote:

Actually, water is .443 psi per foot, salt water .445 psi. *This is derived
from taking 14.7 psi per every 33 foot of depth when scuba diving. *So,
actually, the lake would be 2,934 feet higher, but your figure is close
enough.

HTH

Steve ;-)

You can not take a constant with three significant digits and use it
to get an answer with four significant digits.This is true of your
answer and of Dave_67.

* * * * * * * * * * * * * * * * * * * * * * * * *Dan

The Lake is in Europe and therefore is a metric lake.

What is a 3000 foot high lake here in the US, is in fact a 914.399999
meter lake in Europe. It has to be because that's what was on the
display of the calculator.

Tim.

On May 24, 4:06*pm, Tim Shoppa wrote:
On May 24, 9:34*am, " wrote:









On May 24, 9:27*am, "Steve B" wrote:

Actually, water is .443 psi per foot, salt water .445 psi. *This is derived
from taking 14.7 psi per every 33 foot of depth when scuba diving. *So,
actually, the lake would be 2,934 feet higher, but your figure is close
enough.

HTH

Steve ;-)

You can not take a constant with three significant digits and use it
to get an answer with four significant digits.This is true of your
answer and of Dave_67.

* * * * * * * * * * * * * * * * * * * * * * * * *Dan

The Lake is in Europe and therefore is a metric lake.

What is a 3000 foot high lake here in the US, is in fact a 914.399999
meter lake in Europe. It has to be because that's what was on the
display of the calculator.

Oh I made a mistake. It was not just a european lake but also a roman
lake. Therefore I must use roman numerals.

So make it CMXIV.CCCXCIX meters high.

Tim.

wrote:
On May 24, 9:27*am, "Steve B" wrote:

Actually, water is .443 psi per foot, salt water .445 psi. *This is
derived from taking 14.7 psi per every 33 foot of depth when scuba
diving. *So, actually, the lake would be 2,934 feet higher, but your
figure is close enough.

You can not take a constant with three significant digits and use it
to get an answer with four significant digits.This is true of your
answer and of Dave_67.

And that's notwithstanding the fact that the original information was
to one significant digit (3000').

Hope This Helps Too!
Rich

In article , "Steve B" wrote:

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote

Let's say they fetched the water from a mountain lake. If the lake were
3000' above the point of use, then the total available water column
pressure would be 1300psi. Now, of course, it's "open", and not held in
a closed column. So, in fact, the pressure is 0 psig at any point along
the aquaduct. But the _available_ column pressure is 1300psi, 3000' below
the source, if enclosed.

Simple, typical, journalistic, wrong-headed interpretation of physics.

LLoyd

Actually, water is .443 psi per foot, salt water .445 psi. This is derived
from taking 14.7 psi per every 33 foot of depth when scuba diving.

Actually, fresh water is 0.434 psi per foot. This is derived from the mass of
a column of water one square inch in area and one foot high, and yields one
atmosphere per 33.9 feet, not 33.

So actually, the lake would be 2,934 feet higher, but your figure is close
enough.

So actually, the lake would be 2998 feet higher, and his figure is much closer
than yours.

HTH.

"Doug Miller" wrote in message
...
In article , "Steve B"
wrote:

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote

Let's say they fetched the water from a mountain lake. If the lake were
3000' above the point of use, then the total available water column
pressure would be 1300psi. Now, of course, it's "open", and not held in
a closed column. So, in fact, the pressure is 0 psig at any point along
the aquaduct. But the _available_ column pressure is 1300psi, 3000'
below
the source, if enclosed.

Simple, typical, journalistic, wrong-headed interpretation of physics.

LLoyd

Actually, water is .443 psi per foot, salt water .445 psi. This is
derived
from taking 14.7 psi per every 33 foot of depth when scuba diving.

Actually, fresh water is 0.434 psi per foot. This is derived from the mass
of
a column of water one square inch in area and one foot high, and yields
one
atmosphere per 33.9 feet, not 33.

So actually, the lake would be 2,934 feet higher, but your figure is close
enough.

So actually, the lake would be 2998 feet higher, and his figure is much
closer
than yours.

HTH.

It's been a very long time since commercial diving school in 1974. I'm
surprised I got it as close as I did.

For diving purposes, atmosphere markers are at 33' multiples.

Steve

"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:
" fired this volley in

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

As typically done by video journalists, they mix, mish, and mash techno-
babble until they come up with something that sounds "good", then go with
it.

Let's say they fetched the water from a mountain lake. If the lake were
3000' above the point of use, then the total available water column
pressure would be 1300psi. Now, of course, it's "open", and not held in
a closed column. So, in fact, the pressure is 0 psig at any point along
the aquaduct. But the _available_ column pressure is 1300psi, 3000' below
the source, if enclosed.

Simple, typical, journalistic, wrong-headed interpretation of physics.

They got their science education from Saturday Matinee "B" Sci-Fi movies.

Cheers!
Rich

Rich Grise on Tue, 24 May 2011 13:04:28
-0700 typed in rec.crafts.metalworking the following:
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:
" fired this volley in

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

As typically done by video journalists, they mix, mish, and mash techno-
babble until they come up with something that sounds "good", then go with
it.

Let's say they fetched the water from a mountain lake. If the lake were
3000' above the point of use, then the total available water column
pressure would be 1300psi. Now, of course, it's "open", and not held in
a closed column. So, in fact, the pressure is 0 psig at any point along
the aquaduct. But the _available_ column pressure is 1300psi, 3000' below
the source, if enclosed.

Simple, typical, journalistic, wrong-headed interpretation of physics.

They got their science education from Saturday Matinee "B" Sci-Fi movies.

The animated ones.

IMHO.

pyotr
--
pyotr filipivich
We will drink no whiskey before its nine.
It's eight fifty eight. Close enough!

pyotr filipivich wrote:
Rich Grise on Tue, 24 May 2011 13:04:28
-0700 typed in rec.crafts.metalworking the following:
"Lloyd E. Sponenburgh" lloydspinsidemindspring.com wrote:
" fired this volley in

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

As typically done by video journalists, they mix, mish, and mash techno-
babble until they come up with something that sounds "good", then go
with it.

Let's say they fetched the water from a mountain lake. If the lake were
3000' above the point of use, then the total available water column
pressure would be 1300psi. Now, of course, it's "open", and not held in
a closed column. So, in fact, the pressure is 0 psig at any point along
the aquaduct. But the _available_ column pressure is 1300psi, 3000'
below the source, if enclosed.

Simple, typical, journalistic, wrong-headed interpretation of physics.

They got their science education from Saturday Matinee "B" Sci-Fi movies.

The animated ones.

IMHO.

Nah, I'm too old-school for that. I'm thinking the likes of these:
http://www.imdb.com/title/tt0047573/
http://www.imdb.com/title/tt0050177/
http://www.imdb.com/title/tt0051418/

Admittedly, Marvin the Martian was animated. ;-)

Cheers!
Rich

On Mon, 23 May 2011 23:37:32 -0700 (PDT), "
wrote:

This does not seem right to me:

History Chanel Modern Marvels
Season 10, Episode 15

Hydraulics

8 minutes into the episode:

[Narrator voice Lloyd Sherr (stage name Max Raphael] "By 30 B.C. The
Roman empire... the aqueduct"

[Prof. Thanos Papanicolaou IIHR University of Iowa] "The Romans they
realized they had to feed bigger areas then they had to have a system
where they can carry large quantities and same time use the concept of
gravity."

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

That, of course, is a mis statement by history channel. The technology
for high pressure piping didn't exist. Nor did the pumps. To do 1300
psi with gravity would take (2.2 feet per 1psi IIRC) nearly 3000 ft.
vertical over a short distance.

That doesn't take away from the engineering excellence of their water
system. Boggles the mind as to how it was done with the technology of
the day.

Karl

On May 24, 7:56*am, Karl Townsend
wrote:
On Mon, 23 May 2011 23:37:32 -0700 (PDT), "
wrote:
This does not seem right to me:

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

That, of course, is a mis statement by history channel. The technology
for high pressure piping didn't exist. Nor did the pumps. To do 1300
psi with gravity would take (2.2 feet per 1psi IIRC) nearly 3000 ft.
vertical over a short distance.

That doesn't take away from the engineering excellence of their water
system. Boggles the mind as to how it was done with the technology of
the day.

Karl-


AFAIK the highest pressure ancient system supplied Pergamon in Turkey.
They had to use bronze instead of the normal lead or clay pipes to
contain the pressure.
http://www.romanaqueducts.info/aquas...esPergamon.jpg
Frontinus and Vitruvius wrote first-hand Latin descriptions of the
water systems; L. Sprague De Camp gives a modern one in "The Ancient
Engineers".
http://www.amazon.com/Ancient-Engine.../dp/0345320298

Ed, is that an appropriate use of a semicolon?
jsw

Jim Wilkins wrote:

AFAIK the highest pressure ancient system supplied Pergamon in Turkey.
They had to use bronze instead of the normal lead or clay pipes to
contain the pressure.
http://www.romanaqueducts.info/aquas...esPergamon.jpg
Frontinus and Vitruvius wrote first-hand Latin descriptions of the
water systems; L. Sprague De Camp gives a modern one in "The Ancient
Engineers".
http://www.amazon.com/Ancient-Engine.../dp/0345320298

Ed, is that an appropriate use of a semicolon?

It is, but who's Ed?
http://writing.wisc.edu/Handbook/Semicolons.html
from:
http://www.google.com/search?q=proper+use+of+semicolon

Cheers!
Rich

"Jim Wilkins" wrote in message
...
On May 24, 7:56 am, Karl Townsend
wrote:
On Mon, 23 May 2011 23:37:32 -0700 (PDT), "
wrote:
This does not seem right to me:

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

That, of course, is a mis statement by history channel. The technology
for high pressure piping didn't exist. Nor did the pumps. To do 1300
psi with gravity would take (2.2 feet per 1psi IIRC) nearly 3000 ft.
vertical over a short distance.

That doesn't take away from the engineering excellence of their water
system. Boggles the mind as to how it was done with the technology of
the day.

Karl-


AFAIK the highest pressure ancient system supplied Pergamon in Turkey.
They had to use bronze instead of the normal lead or clay pipes to
contain the pressure.
http://www.romanaqueducts.info/aquas...esPergamon.jpg
Frontinus and Vitruvius wrote first-hand Latin descriptions of the
water systems; L. Sprague De Camp gives a modern one in "The Ancient
Engineers".
http://www.amazon.com/Ancient-Engine.../dp/0345320298

Ed, is that an appropriate use of a semicolon?
jsw

It's legal, but the two clauses are distinct ideas, and I would not choose
it. I'd write it as two sentences.

If it was contained in a larger paragraph specifically about descriptions of
ancient water systems, it could be a good way to make the rhythm of the
paragraph work better. That's a matter of style, however, not grammar.
Grammatically, what you wrote is perfectly Ok.

editor's hat off

--
Ed Huntress

"Jim Wilkins" wrote in message
...

On May 24, 7:56 am, Karl Townsend
wrote:
On Mon, 23 May 2011 23:37:32 -0700 (PDT), "
wrote:
This does not seem right to me:

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

That, of course, is a mis statement by history channel. The technology
for high pressure piping didn't exist. Nor did the pumps. To do 1300
psi with gravity would take (2.2 feet per 1psi IIRC) nearly 3000 ft.
vertical over a short distance.

That doesn't take away from the engineering excellence of their water
system. Boggles the mind as to how it was done with the technology of
the day.

Karl-


AFAIK the highest pressure ancient system supplied Pergamon in Turkey.
They had to use bronze instead of the normal lead or clay pipes to
contain the pressure.
http://www.romanaqueducts.info/aquas...esPergamon.jpg
Frontinus and Vitruvius wrote first-hand Latin descriptions of the
water systems; L. Sprague De Camp gives a modern one in "The Ancient
Engineers".
http://www.amazon.com/Ancient-Engine.../dp/0345320298

Ed, is that an appropriate use of a semicolon?
jsw


Reply:
Some of the old aqueducts are still working. those fountains in Rome are
still fed by that old piping. And the hydraulic cement used was probably
better than you can get today.

On Tue, 24 May 2011 06:56:16 -0500, Karl Townsend
wrote:

On Mon, 23 May 2011 23:37:32 -0700 (PDT), "
wrote:

This does not seem right to me:

History Chanel Modern Marvels
Season 10, Episode 15

Hydraulics

8 minutes into the episode:

[Narrator voice Lloyd Sherr (stage name Max Raphael] "By 30 B.C. The
Roman empire... the aqueduct"

[Prof. Thanos Papanicolaou IIHR University of Iowa] "The Romans they
realized they had to feed bigger areas then they had to have a system
where they can carry large quantities and same time use the concept of
gravity."

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

That, of course, is a mis statement by history channel. The technology
for high pressure piping didn't exist. Nor did the pumps. To do 1300
psi with gravity would take (2.2 feet per 1psi IIRC) nearly 3000 ft.
vertical over a short distance.

1,300psi in open troughs? Why didn't it "fall out"?


That doesn't take away from the engineering excellence of their water
system. Boggles the mind as to how it was done with the technology of
the day.

Yes, the Romans did much better than MickeyD did with their arches.

--
Doubt 'til thou canst doubt no more...doubt is thought and thought
is life. Systems which end doubt are devices for drugging thought.
-- Albert Guerard

"Larry Jaques" wrote in message
...

On Tue, 24 May 2011 06:56:16 -0500, Karl Townsend
wrote:

On Mon, 23 May 2011 23:37:32 -0700 (PDT), "
wrote:

This does not seem right to me:

History Chanel Modern Marvels
Season 10, Episode 15

Hydraulics

8 minutes into the episode:

[Narrator voice Lloyd Sherr (stage name Max Raphael] "By 30 B.C. The
Roman empire... the aqueduct"

[Prof. Thanos Papanicolaou IIHR University of Iowa] "The Romans they
realized they had to feed bigger areas then they had to have a system
where they can carry large quantities and same time use the concept of
gravity."

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

That, of course, is a mis statement by history channel. The technology
for high pressure piping didn't exist. Nor did the pumps. To do 1300
psi with gravity would take (2.2 feet per 1psi IIRC) nearly 3000 ft.
vertical over a short distance.

1,300psi in open troughs? Why didn't it "fall out"?


That doesn't take away from the engineering excellence of their water
system. Boggles the mind as to how it was done with the technology of
the day.

Yes, the Romans did much better than MickeyD did with their arches.

--
Doubt 'til thou canst doubt no more...doubt is thought and thought
is life. Systems which end doubt are devices for drugging thought.
-- Albert Guerard


Lots of the aqueducts were closed concrete pipes. Not sluices.

On May 24, 2:37*am, "
wrote:
This does not seem right to me:

History Chanel Modern Marvels
Season 10, Episode 15

Hydraulics

8 minutes into the episode:

[Narrator voice Lloyd Sherr (stage name Max Raphael] "By 30 B.C. The
Roman empire... the aqueduct"

[Prof. Thanos Papanicolaou IIHR University of Iowa] "The Romans they
realized they had to feed bigger areas then they had to have a system
where they can carry large quantities and same time use the concept of
gravity."

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

Hmmm, one PSI = 2.3 feet of head, 1300x2.3 = 2990 feet, seems like a
bit much of a sealed drop, even for the romans.

Dave

On Mon, 23 May 2011 23:37:32 -0700 (PDT), "
wrote:

This does not seem right to me:

History Chanel Modern Marvels
Season 10, Episode 15

Hydraulics

8 minutes into the episode:

[Narrator voice Lloyd Sherr (stage name Max Raphael] "By 30 B.C. The
Roman empire... the aqueduct"

[Prof. Thanos Papanicolaou IIHR University of Iowa] "The Romans they
realized they had to feed bigger areas then they had to have a system
where they can carry large quantities and same time use the concept of
gravity."

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."


Obviously the ancients knew many secrets that have been lost to modern
man :-)

On May 24, 9:20*am, john B. wrote:
...
Obviously the ancients knew many secrets that have been lost to modern
man :-)-

They were lost to European medieval man until he recaptured Spain and
read the library books. They still seem to be lost to clean-fingernail
writer types who haven't learned the details of the old manual trades.
I was in Mensa and saw how incompetent they could be at simple tasks
like paddling a canoe straight or lighting a fire.

jsw

On Tue, 24 May 2011 07:34:53 -0700 (PDT), Jim Wilkins
wrote:

On May 24, 9:20*am, john B. wrote:
...
Obviously the ancients knew many secrets that have been lost to modern
man :-)-

They were lost to European medieval man until he recaptured Spain and
read the library books. They still seem to be lost to clean-fingernail
writer types who haven't learned the details of the old manual trades.
I was in Mensa and saw how incompetent they could be at simple tasks
like paddling a canoe straight or lighting a fire.

jsw

I've read these descriptions of the shortcomings of the educated many
times and in most cases they are of little merit. Reverse the equation
and you are discussing your plumber's shortcomings because he doesn't
understand quantum mechanics.

A long time ago someone said "the shoemaker to his last".

On May 24, 8:37*pm, john B. wrote:
...Reverse the equation
and you are discussing your plumber's shortcomings because he doesn't
understand quantum mechanics.

As long as he doesn't pretend to, and write a book on it.

jsw

On Tue, 24 May 2011 18:13:36 -0700 (PDT), Jim Wilkins
wrote:

On May 24, 8:37*pm, john B. wrote:
...Reverse the equation
and you are discussing your plumber's shortcomings because he doesn't
understand quantum mechanics.

As long as he doesn't pretend to, and write a book on it.

jsw

If he did he would probably be overlooked in the multitude of "how to"
books written by people who don't know what they are doing either.

wrote in message
...
This does not seem right to me:

History Chanel Modern Marvels
Season 10, Episode 15

Hydraulics

8 minutes into the episode:

[Narrator voice Lloyd Sherr (stage name Max Raphael] "By 30 B.C. The
Roman empire... the aqueduct"

[Prof. Thanos Papanicolaou IIHR University of Iowa] "The Romans they
realized they had to feed bigger areas then they had to have a system
where they can carry large quantities and same time use the concept of
gravity."

[Narrator voice Lloyd Sherr (stage name Max Raphael)] "In the
aqueducts water flowed swiftly, producing as much as 1300 pounds of
pressure per square inch. 25 times the standard water pressure of a
city today."

I have noticed before that the Modern Marvels series has an awful lot of
errors. What they are really referring to is the inverted siphon portion of
an aqueduct. Instead of building a bridge across a valley, they would lay a
sealed lead pipe down the valley and up the other side. The high pressure
occured inside the pipe at the bottom of the valley. However they highest
drop in a Roman siphon was about 100 meters
http://www.romanaqueducts.info/q&a/3design.htm This still gives an
impressive pressure of 142 p.s.i. It looks like one of their researchers
was off by a factor of 10.

On May 24, 12:34*pm, "anorton"
wrote:
... city today."

I have noticed before that the Modern Marvels series has an awful lot of
errors. What they are really referring to is the inverted siphon portion of
an aqueduct. Instead of building a bridge across a valley, they would lay a
sealed lead pipe down the valley and up the other side. The high pressure
occured inside the pipe at the bottom of the valley. *However they highest
drop in a Roman siphon was about 100 meters
http://www.romanaqueducts.info/q&a/3design.htm*
This still gives an
impressive pressure of 142 p.s.i. *It looks like one of their researchers
was off by a factor of 10.-

There is a minor ancient mystery therein. Vitruvius says the belly
section of pipe needs "colliquiaria" to relieve the force of air, a
word not defined elsewhere. Some writers deny the possibility of air
in the lower section, but I think it may be sucked in by a whirlpool
in the header tank at the top of the downpipe when the water flow is
lower than intended, collect at accidental high spots and impede the
flow. They would certainly have noticed air bubbling out at the tank
on the exit end.

jsw