"Don Foreman" wrote in message
...
On Sat, 20 Dec 2003 03:28:16 -0800, Ken Cutt
wrote:

Mark wrote:


Peter Reilley wrote:

When you throw the block and rope into the water, you have, in

effect, changed the shape of the hull, without changing its weight,
so the
amount of water displaced does not change. Therefor, the pond level
does
not change. Making the rope "weightless" or of neutral buoyancy does
not
make any difference. The water level does not change.



I believe that we have a correct answer.



What's interesting is the boat would ride higher in the water but the
level in the tank would remain the same.

Wow! So if I unclamp my outboard motor, tie a rope to it and toss it
overboard, then I'll ride higher in the water so I can cast further!

Wow! So if I unclamp my outboard motor, tie a rope to it and toss it
overboard, then I'll ride higher in the water so I can cast further!

By golly, Don! You finally got one right. This here physics stuff ain't so
hard is it?

Bob Swinney



"Don Foreman" wrote in message
...
On Sat, 20 Dec 2003 03:28:16 -0800, Ken Cutt
wrote:

Mark wrote:


Peter Reilley wrote:

When you throw the block and rope into the water, you have, in

effect, changed the shape of the hull, without changing its weight,
so the
amount of water displaced does not change. Therefor, the pond level
does
not change. Making the rope "weightless" or of neutral buoyancy does
not
make any difference. The water level does not change.



I believe that we have a correct answer.



What's interesting is the boat would ride higher in the water but the
level in the tank would remain the same.

Don Foreman wrote: Wow! So if I unclamp my outboard motor, tie a rope to
it and toss it overboard, then I'll ride higher in the water so I can cast
further!
^^^^^^^^^^^
If you tie a rope to the motor, unclamp it from the transom, and throw it
over the stern, what will that do to the attitude of the boat? Will the
stern or the bow go up?

On Mon, 22 Dec 2003 04:16:48 GMT, "Leo Lichtman"
wrote:


Don Foreman wrote: Wow! So if I unclamp my outboard motor, tie a rope to
it and toss it overboard, then I'll ride higher in the water so I can cast
further!
^^^^^^^^^^^
If you tie a rope to the motor, unclamp it from the transom, and throw it
over the stern, what will that do to the attitude of the boat? Will the
stern or the bow go up?

Yes,

On Sun, 21 Dec 2003 22:40:31 -0600, Don Foreman
wrote:

On Mon, 22 Dec 2003 04:16:48 GMT, "Leo Lichtman"
wrote:


Don Foreman wrote: Wow! So if I unclamp my outboard motor, tie a rope to
it and toss it overboard, then I'll ride higher in the water so I can cast
further!
^^^^^^^^^^^
If you tie a rope to the motor, unclamp it from the transom, and throw it
over the stern, what will that do to the attitude of the boat? Will the
stern or the bow go up?

Yes,


Unless you get the line accidentally hooked around a tholepin G.


Mark Rand
RTFM

Ted Edwards wrote:
Gary Coffman wrote:

Actually, in the boat it displaces its *weight*, not mass, but otherwise
correct.

Unless the boat and block are in different gravitational fields, the
result is the same. W=mg.

The boat and the block are in different gravitational fields.
Say the block is moved down 2m from its position in the boat.

Now, fun question.
Is it now slightly heavier, slightly lighter, or the same weight.

Ian Stirling wrote:
Ted Edwards wrote:
Gary Coffman wrote:

Actually, in the boat it displaces its *weight*, not mass, but
otherwise correct.

Unless the boat and block are in different gravitational fields, the
result is the same. W=mg.

The boat and the block are in different gravitational fields.
Say the block is moved down 2m from its position in the boat.

Now, fun question.
Is it now slightly heavier, slightly lighter, or the same weight.
My instinct says it is lighter assuming that the block is now below the
waterline.
Now; For a clue as to why I think this is true I would like to pose another
question.
At what distance from the center of the earth, would the block be
'heaviest'?
There has to be a 'simple' answer for this.

Regards.
Ken.

On Tue, 23 Dec 2003 18:20:06 -0800, "Ken Davey" wrote:

snip

Now; For a clue as to why I think this is true I would like to pose another
question.
At what distance from the center of the earth, would the block be
'heaviest'?
There has to be a 'simple' answer for this.

Objects are heaviest at the surface of the earth. IIRC Gravity is proportional
to distance-from-centre/radius below the centre and proportional to
distance-from-centre/radius^2 above the centre.

Mark Rand
RTFM

Mark Rand wrote:
On Tue, 23 Dec 2003 18:20:06 -0800, "Ken Davey" wrote:

snip

Now; For a clue as to why I think this is true I would like to pose another
question.
At what distance from the center of the earth, would the block be
'heaviest'?
There has to be a 'simple' answer for this.

Objects are heaviest at the surface of the earth. IIRC Gravity is proportional
to distance-from-centre/radius below the centre and proportional to
distance-from-centre/radius^2 above the centre.

Given a homogenous spherical earth.
If the boat is in a mountain lake, it may work the other way.

Mark Rand wrote:
On Tue, 23 Dec 2003 18:20:06 -0800, "Ken Davey"... wrote:
....
Now; For a clue as to why I think this is true I would like to pose another
question.
At what distance from the center of the earth, would the block be
'heaviest'?
There has to be a 'simple' answer for this.

Objects are heaviest at the surface of the earth. IIRC Gravity is proportional
to distance-from-centre/radius below the centre and proportional to
distance-from-centre/radius^2 above the centre.
....

If by "below the centre" you mean southern hemisphere, then your
brain has let you down. There is no difference in gravitational
formulae between north and south hemispheres of earth.

Anyhow, for items above the surface of the earth, gravitational
attraction is inversely proportional to the square of distance
from the center of the Earth, of course by Newton's F=G*m1*m2/r^2
formula. Below the surface, say at distance t from center, if
m2=mass of Earth, R=radius of Earth, then F=G*m1*m2*(t/R)^3/t^2
=G*m1*m2*t/R^3, which as you say is proportional to distance
to center.[*]
-jiw
[*] (t/R)^3 = the proportion of Earth's mass inside a sphere of
radius t. The mass outside that sphere is a hollow shell, and
its inverse square field cancels out at all points inside.

On Wed, 24 Dec 2003 19:33:08 +0000, Ian Stirling wrote:

Mark Rand wrote:
On Tue, 23 Dec 2003 18:20:06 -0800, "Ken Davey" wrote:

snip

Now; For a clue as to why I think this is true I would like to pose another
question.
At what distance from the center of the earth, would the block be
'heaviest'?
There has to be a 'simple' answer for this.

Objects are heaviest at the surface of the earth. IIRC Gravity is proportional
to distance-from-centre/radius below the centre and proportional to
distance-from-centre/radius^2 above the centre.

Given a homogenous spherical earth.
If the boat is in a mountain lake, it may work the other way.
Just to be pedantic - if you had an homogenous earth you wouldn't have a
mountain lake.
--
Neil
Delete delete to reply by email

Ian Stirling wrote:

Given a homogenous spherical earth.


Which does not exist. Which is your point.


At the equator there is centrifugal force which isn't a factor at the
poles, and there is a land mass under the south pole the north pole
doesn't have. Then there's the thing about the earth actually being an oval.

And then there's the thing about densities of the earths crust. And the
thickness. And the turbulent nature of what lies 40 miles down. What
about 2 miles? 3,4,5,6 miles? It all adds up and just how many decimals
does someone want to carry it out to in order to prove their answer?

?

You choose your point on the earths surface, mayhaps I'll find another.

It's a black hole argument. That is, it can suck up any answer without
resolution. Unless we involve a geologist who will tell what spot on
earth has the highest gravimetric verses centrifugal force.



These types of threads are masturbatory.




--

Mark

N.E. Ohio


Never argue with a fool, a bystander can't tell you apart. (S. Clemens,
A.K.A. Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the
suspense. (Gaz, r.moto)

On Fri, 26 Dec 2003 05:57:11 GMT, Mark
wrote:



Ian Stirling wrote:

Given a homogenous spherical earth.


Which does not exist. Which is your point.


At the equator there is centrifugal force which isn't a factor at the
poles, and there is a land mass under the south pole the north pole
doesn't have. Then there's the thing about the earth actually being an oval.

And then there's the thing about densities of the earths crust. And the
thickness. And the turbulent nature of what lies 40 miles down. What
about 2 miles? 3,4,5,6 miles? It all adds up and just how many decimals
does someone want to carry it out to in order to prove their answer?

?

You choose your point on the earths surface, mayhaps I'll find another.

It's a black hole argument. That is, it can suck up any answer without
resolution. Unless we involve a geologist who will tell what spot on
earth has the highest gravimetric verses centrifugal force.



These types of threads are masturbatory.

When I was exploring for oil and gas, we had Gravity Detectors, which
measured the local gravity pull in a given area. Significant
differences in some areas. No idea how they worked.

Gunner

'If you own a gun and have a swimming pool in the yard, the swimming
pool is almost 100 times more likely to kill a child than the gun is.'"
Steven Levitt, UOC prof.

Hey Gunner,

First off, Best of the Season to You, and (I note lately) Yours.

These gravity detectors you mentioned, and I realize your wildcatting
days were some time back........Do you recall the sort of readings you
were getting. I mean, was it in pounds per something, or just some
sort of a scale thing. What would be a "large' variation. Did it
seem to follow the magnetic variations you'd see on an aeronautical or
navigational chart? Why would it influence what you were doing?

Sounds interesting, though for no specific reason..

Take care.

Brian Lawson,
Bothwell, Ontario.
XXXXXXXXXXXXXXXXXXXXXXXX
On Fri, 26 Dec 2003 10:47:29 GMT, Gunner
wrote:

On Fri, 26 Dec 2003 05:57:11 GMT, Mark
wrote:



Ian Stirling wrote:

Given a homogenous spherical earth.


Which does not exist. Which is your point.


At the equator there is centrifugal force which isn't a factor at the
poles, and there is a land mass under the south pole the north pole
doesn't have. Then there's the thing about the earth actually being an oval.

And then there's the thing about densities of the earths crust. And the
thickness. And the turbulent nature of what lies 40 miles down. What
about 2 miles? 3,4,5,6 miles? It all adds up and just how many decimals
does someone want to carry it out to in order to prove their answer?

?

You choose your point on the earths surface, mayhaps I'll find another.

It's a black hole argument. That is, it can suck up any answer without
resolution. Unless we involve a geologist who will tell what spot on
earth has the highest gravimetric verses centrifugal force.



These types of threads are masturbatory.

When I was exploring for oil and gas, we had Gravity Detectors, which
measured the local gravity pull in a given area. Significant
differences in some areas. No idea how they worked.

Gunner

'If you own a gun and have a swimming pool in the yard, the swimming
pool is almost 100 times more likely to kill a child than the gun is.'"
Steven Levitt, UOC prof.

"Gunner" wrote in message
...
On Fri, 26 Dec 2003 05:57:11 GMT, Mark
wrote:



Ian Stirling wrote:

Given a homogenous spherical earth.


Which does not exist. Which is your point.


At the equator there is centrifugal force which isn't a factor at the
poles, and there is a land mass under the south pole the north pole
doesn't have. Then there's the thing about the earth actually being an
oval.

And then there's the thing about densities of the earths crust. And the
thickness. And the turbulent nature of what lies 40 miles down. What
about 2 miles? 3,4,5,6 miles? It all adds up and just how many decimals
does someone want to carry it out to in order to prove their answer?

?

You choose your point on the earths surface, mayhaps I'll find another.

It's a black hole argument. That is, it can suck up any answer without
resolution. Unless we involve a geologist who will tell what spot on
earth has the highest gravimetric verses centrifugal force.



These types of threads are masturbatory.

When I was exploring for oil and gas, we had Gravity Detectors, which
measured the local gravity pull in a given area. Significant
differences in some areas. No idea how they worked.

Gunner

Gravity is quite easy to measure, you just weigh a known mass. You use a
spring
scale and not a balance beam. The gravitometers
used in the old days were simply a scale with a microscope to read the
result.
I saw an old one at a museum. The mechanism used a quartz thread coiled
into a spring.
Quartz was needed because of it's low hysteresis. The entire unit
was built into a can about 5 inches in diameter and 12 inches tall. It was
ruggedly built
so that it could be hauled out in the field for oil exploration. It
probably dated from
the 1950's.

Gravitometers are also used in submarine navigation. You can detect the
presence of underwater mountain ranges.

Pete.

These gravity anomalies are called "vertical deflections" and are the
places where the gravity vector differs from perpendicular to the
earths surface.
Over large iron deposits you will find them to be a bit larger but
they really don't follow the geomagnetic fields to any degree.
I believe they used to test for them with pendulous gyroscopic
acellerometers but I bet the new stuff is a bit more refined.

(Beecrofter) wrote in message . com...
These gravity anomalies are called "vertical deflections" and are the
places where the gravity vector differs from perpendicular to the
earths surface.
Over large iron deposits you will find them to be a bit larger but
they really don't follow the geomagnetic fields to any degree.
I believe they used to test for them with pendulous gyroscopic
acellerometers but I bet the new stuff is a bit more refined.


I have a book on the history of maps and mapmaking. It seems that
back in the 1600's there was a big discussion about how big a degree
was on the earth and the way they chose to measure this was discussed
greatly in this book. They took pendulum clocks, adjusted them to
great precision in France. They then disassembled them carefully,
loaded them on ships and sent them down closer to the equator, to use
in astronomical observatories. They found that the rate of the clock
changed. They correctly assumed that the gravitational field was
different at different places on the earth. I believe that these
clocks qualify as the first precision gravity meters.

We had the gravity constant checked at our laboratory in Houston. We
were using precision dead-weight testers to calibrate pressure gauges
(How precision? 0.1 psi resolution at 20,000 psi static). A shaky old
man in a baseball cap came in with a box about a foot cubed with a
battery pack attached. He set the box on our bench, stared through an
eyepiece, and said it had not stabilized yet. He said he would be
back later, and disappeared for an hour. Then he came in and read the
gravity constant at our location. I think the box had nothing more
precise than a weight with a spring on it, and a scale read with a
microscope. The precision, and stability, came from maintaining a
VERY precise temperature in the box. I.e., the wait for the box to
stabilize better was a wait for the temperature to stabilize.

In summary, "gravity meters" have been around a long time, and don't
require rocket-science to build.

brownnsharp wrote:
(Beecrofter) wrote in message . com...

These gravity anomalies are called "vertical deflections" and are the
places where the gravity vector differs from perpendicular to the
earths surface.
Over large iron deposits you will find them to be a bit larger but
they really don't follow the geomagnetic fields to any degree.
I believe they used to test for them with pendulous gyroscopic
acellerometers but I bet the new stuff is a bit more refined.



I have a book on the history of maps and mapmaking. It seems that
back in the 1600's there was a big discussion about how big a degree
was on the earth and the way they chose to measure this was discussed
greatly in this book. They took pendulum clocks, adjusted them to
great precision in France. They then disassembled them carefully,
loaded them on ships and sent them down closer to the equator, to use
in astronomical observatories. They found that the rate of the clock
changed. They correctly assumed that the gravitational field was
different at different places on the earth. I believe that these
clocks qualify as the first precision gravity meters.

Also a factor is that the vertical component of the centrifugal force
due to the earth's rotation is greatest at the equator.

"brownnsharp" wrote in message
om...
(Beecrofter) wrote in message
. com...
These gravity anomalies are called "vertical deflections" and are the
places where the gravity vector differs from perpendicular to the
earths surface.
Over large iron deposits you will find them to be a bit larger but
they really don't follow the geomagnetic fields to any degree.
I believe they used to test for them with pendulous gyroscopic
acellerometers but I bet the new stuff is a bit more refined.


I have a book on the history of maps and mapmaking. It seems that
back in the 1600's there was a big discussion about how big a degree
was on the earth and the way they chose to measure this was discussed
greatly in this book. They took pendulum clocks, adjusted them to
great precision in France. They then disassembled them carefully,
loaded them on ships and sent them down closer to the equator, to use
in astronomical observatories. They found that the rate of the clock
changed. They correctly assumed that the gravitational field was
different at different places on the earth. I believe that these
clocks qualify as the first precision gravity meters.

At the peak of refinement of pendulum clocks as national standards, before
going atomic/electronic, the clocks easily measured the position of the
moon, and local seasonal groundwater variations.

brownnsharp wrote:
(Beecrofter) wrote in message . com...

These gravity anomalies are called "vertical deflections" and are the
places where the gravity vector differs from perpendicular to the
earths surface.
Over large iron deposits you will find them to be a bit larger but
they really don't follow the geomagnetic fields to any degree.
I believe they used to test for them with pendulous gyroscopic
acellerometers but I bet the new stuff is a bit more refined.



I have a book on the history of maps and mapmaking. It seems that
back in the 1600's there was a big discussion about how big a degree
was on the earth and the way they chose to measure this was discussed
greatly in this book. They took pendulum clocks, adjusted them to
great precision in France. They then disassembled them carefully,
loaded them on ships and sent them down closer to the equator, to use
in astronomical observatories. They found that the rate of the clock
changed. They correctly assumed that the gravitational field was
different at different places on the earth. I believe that these
clocks qualify as the first precision gravity meters.

Principia Mathematica was published in 1687, so they would have had to
be pretty on the ball to think of this, if the date "in the 1600's" even
works out to be mathematically possible.

The temperature is only one of the things that needs to stabilize.
Another problem is air currents inside the box and since the device
must have very low hysteris, it takes a long time to dampen out the
oscilations. I was told that some of the gravity meters had a partial
vacuum in the box to reduce the problem with air currents. A full
vacuum did not provide the damping.
But the guy probably just went to lunch.

I also understand that the usual procedure for gravity surveys used
two gravity meters. One stayed at the starting location and the
gravity was recorded there every so often. The other meter was moved
around the area being surveyed. The reason is that the gravity
measured varies with time. Well with the position of the sun and moon
mostly.

Dan

(brownnsharp) wrote in message

We had the gravity constant checked at our laboratory in Houston. We
were using precision dead-weight testers to calibrate pressure gauges
(How precision? 0.1 psi resolution at 20,000 psi static). A shaky old
man in a baseball cap came in with a box about a foot cubed with a
battery pack attached. He set the box on our bench, stared through an
eyepiece, and said it had not stabilized yet. He said he would be
back later, and disappeared for an hour. Then he came in and read the
gravity constant at our location. I think the box had nothing more
precise than a weight with a spring on it, and a scale read with a
microscope. The precision, and stability, came from maintaining a
VERY precise temperature in the box. I.e., the wait for the box to
stabilize better was a wait for the temperature to stabilize.

In summary, "gravity meters" have been around a long time, and don't
require rocket-science to build.

In summary, "gravity meters" have been around a long time, and don't
require rocket-science to build.

Most of the earths surface is covered by oceans, not an easy place to
stabilize a weight on a spring. Unless you rest it on the seabed.
Thus the space referenced gryo.

There is a bit of a problem here. There were no clocks of sufficient
accuracy at that time! The Dead Beat Escapement was not invented until 1715,
by George Graham. Further, a pendulum clock will change it's rate, even if
moved across a room. There was no effectively accurate temperature
compensated pendulum until about 1720. The mercurial pendulum was introduced
around this time. Regulator clocks are also sensitive to air density. When
used in astronomy, a barometer was always near the clocks, so that a
correction could be made. The early barometers had to be monitored
constantly. Later the recording barometer eased this burden.

Steve R.


"PhysicsGenius" wrote in message
...
brownnsharp wrote:
(Beecrofter) wrote in message
. com...

These gravity anomalies are called "vertical deflections" and are the
places where the gravity vector differs from perpendicular to the
earths surface.
Over large iron deposits you will find them to be a bit larger but
they really don't follow the geomagnetic fields to any degree.
I believe they used to test for them with pendulous gyroscopic
acellerometers but I bet the new stuff is a bit more refined.



I have a book on the history of maps and mapmaking. It seems that
back in the 1600's there was a big discussion about how big a degree
was on the earth and the way they chose to measure this was discussed
greatly in this book. They took pendulum clocks, adjusted them to
great precision in France. They then disassembled them carefully,
loaded them on ships and sent them down closer to the equator, to use
in astronomical observatories. They found that the rate of the clock
changed. They correctly assumed that the gravitational field was
different at different places on the earth. I believe that these
clocks qualify as the first precision gravity meters.

Principia Mathematica was published in 1687, so they would have had to
be pretty on the ball to think of this, if the date "in the 1600's" even
works out to be mathematically possible.

Gunner wrote:


When I was exploring for oil and gas, we had Gravity Detectors, which
measured the local gravity pull in a given area. Significant
differences in some areas. No idea how they worked.

Gunner


You were working on a crew and didn't have a clue as to what you were doing?

Gunner?

Are you making an admission or trolling?




--

Mark

N.E. Ohio


Never argue with a fool, a bystander can't tell you apart. (S. Clemens,
A.K.A. Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the
suspense. (Gaz, r.moto)

On Sun, 28 Dec 2003 05:23:58 GMT, Mark
wrote:



Gunner wrote:


When I was exploring for oil and gas, we had Gravity Detectors, which
measured the local gravity pull in a given area. Significant
differences in some areas. No idea how they worked.

Gunner


You were working on a crew and didn't have a clue as to what you were doing?

Gunner?

Are you making an admission or trolling?

I was running a Mayhew drilling rig, punching holes in the ground,
loading them with various explosives, then moving on the the next
hole, repeating, repeating repeating repeating well over the horizon.

I even at times managed to run a modified ditch witch, and tunneled
primacord several feet under the ground. At others times, I strung
miles of geophones and laid cable. Hummm did a bit of permit managing,
cable repair, jug repair (geophones) and even managed to do a bit of
mechanics work.

On the other hand, I didnt have a clue how the book keepers kept
accounts in order either, but they somehow suceeded without me knowing
how they did it. Same with the folks who did the computing of the
underground structures. They seemed to know what they were
about..despite my ignorance of how they did it.

You really are becoming a bothersome asshole. Is it natural or do you
have to work at it?

Gunner

"Gun Control, the theory that a 110lb grandmother should
fist fight a 250lb 19yr old criminal"

I approve of cynicism. And since I read this a LONG time ago, 10 years
ago at least...

I dug through my book collection to find my Map-making book. The
title is "The Story of Maps" by Lloyd A. Brown, published in 1949.
Excellent reading for the technical minded. On page 224 I found the
reference I mentioned. The reference to gravity was by Isaac Newton,
the experiments regarding the clocks were performed by Jean Richer,
with Cassini and Huygens critically examining the results. The year
was 1673. Newton was quoted as saying the change in clock rate was due
to "a diminution of gravity resulting from a bulging of the earth at
the equater, or from the strong counteracting effect of centrifugal
force in that region"

Many of our ancestors were incredibly sharp...

Speaking of sharp... there was a show on TV about a month ago about a
lost and re-discovered book of mathematics written by Archimedes. It
seems that he had discovered the calculus about 200-300 BC. That
predates Newton by 1500 years or so. Loss of the book, it was claimed
"set mathematics back 1000 years"

brownnsharp wrote:
....
Speaking of sharp... there was a show on TV about a month ago about a
lost and re-discovered book of mathematics written by Archimedes. It
seems that he had discovered the calculus about 200-300 BC. That
predates Newton by 1500 years or so. Loss of the book, it was claimed
"set mathematics back 1000 years"

I don't think "The Sandreckoner" (in which, AIUI, Archimedes gave
"the method of exhaustion, a technique that allows the exact
computation of areas and volumes using ideas that sound very
familiar to students of integral calculus") was lost. What was
lost was Archimedes' solution of the stomachion, and the first
major developments of *combinatorics* rather than *calculus*.
-jiw

http://mathworld.wolfram.com/news/20...19/stomachion/
http://www.maa.org/editorial/mathgam..._11_17_03.html
http://www.pbs.org/wgbh/nova/archimedes/palimpsest.html

Gunner wrote:


I even at times managed to run a modified ditch witch, and tunneled
primacord several feet under the ground.


Directional drilling?


On the other hand, I didnt have a clue how the book keepers kept
accounts in order either, but they somehow suceeded without me knowing
how they did it. Same with the folks who did the computing ...


And this has what to do with knowing the basics of a machine you claimed
to operate? I've worked many places, didn't want to know how the books
were cooked, didn't seem to be needed to understand or operate a machine
under my control.


You really are becoming a bothersome asshole. Is it natural or do you
have to work at it?

Gunner


Nature verses Nurture, the age old question.


Gunner, you must know you draw a huge target on yourself. You can't
offer such a target (and revel in people taking shots) then cry fowl at
the shooting.


Till next time.




--

Mark

N.E. Ohio


Never argue with a fool, a bystander can't tell you apart. (S. Clemens,
A.K.A. Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the
suspense. (Gaz, r.moto)

On Mon, 29 Dec 2003 02:29:12 GMT, Mark
wrote:



Gunner wrote:


I even at times managed to run a modified ditch witch, and tunneled
primacord several feet under the ground.


Directional drilling?

No...for firing a seismic shot in areas that are too rough to drill
vertical holes in, or too boggy to get a drill rig into.

On the other hand, I didnt have a clue how the book keepers kept
accounts in order either, but they somehow suceeded without me knowing
how they did it. Same with the folks who did the computing ...


And this has what to do with knowing the basics of a machine you claimed
to operate? I've worked many places, didn't want to know how the books
were cooked, didn't seem to be needed to understand or operate a machine
under my control.

Please advise where I indicated that I ran the gravity measuring
machine? I indicated that while I was working in that industry..such
a device was in use. Either you have a reading comprehension
problem..or your rather odd delight in finding oddments that you
somehow think may turned against me is getting the best of you.

You really are becoming a bothersome asshole. Is it natural or do you
have to work at it?

Gunner


Nature verses Nurture, the age old question.


Indeed.

Gunner

Gunner, you must know you draw a huge target on yourself. You can't
offer such a target (and revel in people taking shots) then cry fowl at
the shooting.


Till next time.

"Gun Control, the theory that a 110lb grandmother should
fist fight a 250lb 19yr old criminal"

You really are becoming a bothersome asshole. Is it natural or do you
have to work at it?

Gunner

I really have to agree with Gunner on this.
Your reply *was* unmitigated trash.
Ken.
Nature verses Nurture, the age old question.


Gunner, you must know you draw a huge target on yourself. You can't
offer such a target (and revel in people taking shots) then cry fowl
at the shooting.


Till next time.




Mark

N.E. Ohio


Never argue with a fool, a bystander can't tell you apart. (S.
Clemens, A.K.A. Mark Twain)

When in doubt hit the throttle. It may not help but it sure ends the
suspense. (Gaz, r.moto)

On Mon, 29 Dec 2003 21:47:49 -0500, Doug Warner
wrote:

Gunner wrote:


I even at times managed to run a modified ditch witch, and tunneled
primacord several feet under the ground. At others times, I strung

Question. When you set it off, did the explosion break the surface of
the ground? If not, did anyone try digging the area to see if it left
an open channel?

Seldom did it actually "trench", though it did tend to burrow a bit. The
cord was threaded down the backside of a vertical vibrating 30" blade,
and it was fed out as the "ditchwitch" crawled along. When a rock that
wouldnt move was encoutered..one simply lifted the blade a bit and
passed over it, then one put the blade back down deep again and
continued chugging along. The thin blade and vibration tended to repack
the soil back around the det cord.

Why? When the plastic water feed line under my yard spring a leak,
the plumbers made a new trench for the copper replacement. They
wouldn't use a pull-through splitter / puller for some reason.

One faster, less disruptive alternative I though of: Thread a string
of primer cord through the old pipe, Cover up the pits at each end
and set it iff. Ideally, it would leave a temporary channel in the
ground big enough to push the new pipe through. Eventually the earth
would settle back around the new pipe.

Depending on soil composition and depth, it could indeed work. One would
have to start big with the grain weight of the det cord. IRRC..we were
using 200gr which is rather powerful. About 5/16" in diameter IRRC.


I've alway wondered if it would leave a usable open channel in the
ground.


Gunner



"Aren't cats Libertarian? They just want to be left alone.
I think our dog is a Democrat, as he is always looking for a handout"
Unknown Usnet Poster

Heh, heh, I'm pretty sure my dog is a liberal - he has no balls.
Keyton

I am entering all your names into my Book of Geeks. All of you would
do well as members of my wife's family, who would love such a
conversation.

Brownnsharp

A city wide blackout at Tue, 30 Dec 2003 08:00:21 GMT did not prevent Gunner
from posting to rec.crafts.metalworking the following:

Why? When the plastic water feed line under my yard spring a leak,
the plumbers made a new trench for the copper replacement. They
wouldn't use a pull-through splitter / puller for some reason.

One faster, less disruptive alternative I though of: Thread a string
of primer cord through the old pipe, Cover up the pits at each end
and set it iff. Ideally, it would leave a temporary channel in the
ground big enough to push the new pipe through. Eventually the earth
would settle back around the new pipe.

Depending on soil composition and depth, it could indeed work. One would
have to start big with the grain weight of the det cord. IRRC..we were
using 200gr which is rather powerful. About 5/16" in diameter IRRC.

Okay, in the "don't try this at home" category comes the tale of Tom and
the Gophers. Tom, being the resourceful lad that he is, decided to nuke the
little buggers digging up his yard. So one morning, he puts calcium carbide in
the gopher hole and adds water before going to church. On returning, he
inserted a length of fuse and lit it. "And lo, the yard did part like unto the
Red Sea" as the acetylene gas blew his yard into a miniature model of Verdun in
1917. That was only half the problem. Blew part of the neighbor's yard up as
well.

Didn't phase the gophers one bit.





I've alway wondered if it would leave a usable open channel in the
ground.


Gunner

--
pyotr filipivich.
as an explaination for the decline in the US's tech edge, James
Niccol wrote "It used to be that the USA was pretty good at
producing stuff teenaged boys could lose a finger or two playing with."

"pyotr filipivich" wrote in message
...
Okay, in the "don't try this at home" category comes the tale of Tom and
the Gophers. Tom, being the resourceful lad that he is, decided to nuke
the
little buggers digging up his yard. So one morning, he puts calcium
carbide in
the gopher hole and adds water before going to church. On returning, he
inserted a length of fuse and lit it. "And lo, the yard did part like
unto the
Red Sea" as the acetylene gas blew his yard into a miniature model of
Verdun in
1917. That was only half the problem. Blew part of the neighbor's yard
up as
well.

Didn't phase the gophers one bit.


I *knew* this sounded familiar.

Tom's technique was flawed. Here are the correct instructions, from
"Popular Mechanics Shop Notes for 1915."

http://www.mendosus.com/jpg/moles.jpg

If all else fails...

Jeff

I just came across this thread and for once I can contribute a little.
Back in the eighties I used to build gravimeters. They are indeed
exquisite instruments. If there was someplace to post pictures to I would
post one of a sensor. Most of the speculations are on the right track.
They all have a proof mass and a means of support, usually a spring, and
a position detection system which can be optical or electronic. Our
instruments operated at a reduced pressure to reduce convection currents
but still high enough to provide some damping. The gas does not have to
be air. A two stage oven will stabilize the sensor to within about one
millidegree and then we would compenstate in software below that
resolution. The proof mass weighed approx. one gram, and was suspended
from a spring. Gravity variations were determined by measuring the
voltage required to electrostatically return the mass to a null position.
This was a 'relative' gravimeter. Absolute gravimeters are very different
things, usually employing a corner cube reflector dropped or tossed in a
vacuum. FYI the gravity unit is a Gal (for Galileo) and since it is so
large a milliGal is the common unit. Field strength is approx 980000
milliGal and our portable gravimeters could measure to 1 microGal. A
worldwide instrument requires a range of 7000 milliGal. Not all older
instruments could operate at all locations on Earth without resetting.
The principals that these instruments operate on are not 'rocket
science', I will agree, but the skills required to build them are rare.

(Dan Caster) wrote in news:3183eab.0312262345.71cd47e9
@posting.google.com:

The temperature is only one of the things that needs to stabilize.
Another problem is air currents inside the box and since the device
must have very low hysteris, it takes a long time to dampen out the
oscilations. I was told that some of the gravity meters had a partial
vacuum in the box to reduce the problem with air currents. A full
vacuum did not provide the damping.
But the guy probably just went to lunch.

I also understand that the usual procedure for gravity surveys used
two gravity meters. One stayed at the starting location and the
gravity was recorded there every so often. The other meter was moved
around the area being surveyed. The reason is that the gravity
measured varies with time. Well with the position of the sun and moon
mostly.

Dan

(brownnsharp) wrote in message

We had the gravity constant checked at our laboratory in Houston. We
were using precision dead-weight testers to calibrate pressure gauges
(How precision? 0.1 psi resolution at 20,000 psi static). A shaky old
man in a baseball cap came in with a box about a foot cubed with a
battery pack attached. He set the box on our bench, stared through an
eyepiece, and said it had not stabilized yet. He said he would be
back later, and disappeared for an hour. Then he came in and read the
gravity constant at our location. I think the box had nothing more
precise than a weight with a spring on it, and a scale read with a
microscope. The precision, and stability, came from maintaining a
VERY precise temperature in the box. I.e., the wait for the box to
stabilize better was a wait for the temperature to stabilize.

In summary, "gravity meters" have been around a long time, and don't
require rocket-science to build.

"The principals that these instruments operate on are not 'rocket
science', I will agree, but the skills required to build them are
rare.

I would NEVER contest that!

In truth, if you took 20,000 average people, I bet not over 100 of
them could operate a lathe. Three might fix a watch. Three might be
able to build a reflector telescope. I doubt that you could find 1 in
20,000 that could build a lathe or a milling machine that was
reasonably accurate (a good welder might make some kind of servicable
tool). Especially if no working lathes and milling machines were
available to start with... But a gravity meter??? This is not your
usual instrument.

In article , brownnsharp
says...

In truth, if you took 20,000 average people, I bet not over 100 of
them could operate a lathe.

If you were willing to restrict that 20,000 to individuals
below the age of 20, I would lay odds that not over 100
of them would even know what a lathe *is*, or be
able to pick one out of a lineup, much less operate
the thing.

Jim

==================================================
please reply to:
JRR(zero) at yktvmv (dot) vnet (dot) ibm (dot) com
==================================================

"jim rozen" wrote in message
...
In article , brownnsharp
says...

In truth, if you took 20,000 average people, I bet not over 100 of
them could operate a lathe.

If you were willing to restrict that 20,000 to individuals
below the age of 20, I would lay odds that not over 100
of them would even know what a lathe *is*, or be
able to pick one out of a lineup, much less operate
the thing.

Not in Australia, Jim (or at least my state of NSW).
"Technology" is a mandatory subject for years 7&8 (~12-14 y.o.), and all
students study it for 200hrs over 2 years.
In *my* experience, half of that is spent in a room fitted with lathes. At
least a few of those hours are spent *on* the lathes.
If - say - 50% went on to adulthood with a working knowledge of lathes I
wouldn't be surprised. (In *my* classes its closer to 95%)

Don't give up yet.

Jeff

Very Interesting!! Does everyone take the courses, or only the guys?
In the 50's when I was in Junior High, many of the guys took "shop",
which was a woodworking only kind of thing. One course, 1 hour twice a
week, for one year. I understand that most of these courses have been
phased out because of liability problems and expense.

I have always been horrified at how little technology, aside from
computers, is taught in the modern American school. Most people just
kinda pick it up as they grow older.

Brownnsharp

On 4 Jan 2004 10:42:11 -0800, the renowned
(brownnsharp) wrote:

Very Interesting!! Does everyone take the courses, or only the guys?
In the 50's when I was in Junior High, many of the guys took "shop",
which was a woodworking only kind of thing. One course, 1 hour twice a
week, for one year. I understand that most of these courses have been
phased out because of liability problems and expense.

When I was in HS (Southern Ontario, early seventies), the guys took
shop- electrical, auto, woodworking, drafting and machine shop, all
beautifully equipped with the latest equipment (including even EDM
machines) in a very new facility. Kind of a "golden age", I think.
Even those who were not that interested at the time learned a lot. The
"two year program" guys who were definitely not on a college or
university track took more intensive shop courses to prepare them for
their future in the trades. From what I've seen virtually all of that
stuff is gone now, and all the kids go the four years (was four or
five, depending) regardless of their abilities and interests.

I have always been horrified at how little technology, aside from
computers, is taught in the modern American school. Most people just
kinda pick it up as they grow older.

Brownnsharp

Or not.

Best regards,
Spehro Pefhany
--
"it's the network..." "The Journey is the reward"
Info for manufacturers: http://www.trexon.com
Embedded software/hardware/analog Info for designers: http://www.speff.com