misunderstandings that seem inexplicable at the time

In article ,
John Rumm wrote:
However, I still can't see how you can describe a second display as a
mirror unless it is at least displaying the same image... e.g. plugging
a monitor into the VGA port on many laptops would allow the external
screen to show the same as the internal - that you could call a mirror.

That's what I'd have thought - a 'mirror' is used in IT parlance for a
site that offers an alternative source of the same downloads.

--
*He's not dead - he's electroencephalographically challenged

Dave Plowman London SW
To e-mail, change noise into sound.

In article ,
Andy Wade wrote:
- ELV in turn means a nominal voltage not exceeding 50 V for AC or 120 V
for DC, whether between conductors or to earth.

My Fluke DVM gives a warning at approx 30 volts. I've never quite worked
out why...

Most people would probably not think of mains voltage as "low".

This is true. There are plenty of similar examples. The measurement of
brickwork comes to mind - a 9-inch brick wall is one brick thick, not
two.

Eh? A 9 inch brick wall in its simplest form comprises bricks laid both
lengthwise and crosswise - ie headers and stretchers. So is approx 9"
thick.

--
*I'm not your type. I'm not inflatable.

Dave Plowman London SW
To e-mail, change noise into sound.

In article , Bill Wright
wrote:

"John Rumm" wrote in message
et...
Sounds like the IT man was talking out of the back of his head
anyway... with a dual head (i.e. two monitor) system, the second
screen as you describe it is acting as an extended desktop. So its
not a mirror, but and extension to your current screen. You can drag
icons there if you want.

No, the IT man is very good. The problem was semantic. I fully
understand how the language used in one specialised area does not
translate into common parlance or into a different specialised area.

To unpick the 'semantics' of your own comment. :-) He may be "good" in
his ability to setup or use computer systems. But that does not mean that
his choice of words was appropriate. I know various people who use multiple
monitors in all kinds of systems. I can't recall any of them being called a
'mirror' unless one screen did duplicate exactly what appeared on the other
Dual head is a much more common term if the screens can show different
things and you can do something like draw a window from one to the other.

So it sounds to me like he may have heard the word in one context, and
incorrectly assumed it was correct in another. Easily done. But I'm not a
computer scientist, so canna be responsible for their mangling the
language. I get my own back by writing awful programs. 8-]

WRT the other examples you gave I fear that the problem is often that the
person *thinks* they know what they are talking about, but simply don't. I
encounter this quite a lot. The result can be even more confusing when the
terms used seem to make sense until you realise that their mistake is
actually covering over the real problem or situation. In effect, they have
picked up the jargon from somewhere, but don't really understand what it us
used to describe.

I often get people contacting me about audio gear or electronics as a
result of the webpages I produce. Many seem to want me to do their
school/uni project for them... :-) ...however I also get ones where
someone has a problem with an item of equipment. These often have the form:

"I have an XYZ and when I do ABC the fuse blows... "

followed by

"I think the reason for this is that the dooflanger needs flunging... "

When it seems quite clear if you know the XYZ that this is somewhat
unlikely or absurd.

You will be familiar with this I suspect, from the phone calls you get.
:-)

The problem is that they generally fail to tell you what the relevant
factors are as they don't realise what is actually happening. So instead
they give you red herrings and erronious or irrelevant conclusions. Unless
you recognise the real problem all it tells you is that they have a problem
they don't understand.

It then can take some time before you can get them to reveal the actual
info needed to diagnose (if possible via email/phone/etc) what is wrong.
Until then you are left with the feeling that their description doesn't add
up, but not know what is actually happening.

Confusing 120W with 12V seems par for the course. If you look in the
current "Hi Fi Plus" audio mag you can find a box where a speaker designer
talks about how much torque he can apply to bolts in speaker cabinets. The
units sic given are "Newton-pounds".

Quite refreshing to get units that try to cater for both SI and Imperial.
Even more international than SI, I guess. ;-

Shame, though, that the result doesn't seem quite right for a torque...

Perhaps the box in the mag should have been headed, "Careless Torque."

Slainte,

Jim

--
Change 'noise' to 'jcgl' if you wish to email me.
Electronics http://www.st-and.ac.uk/~www_pa/Scot...o/electron.htm
Armstrong Audio http://www.audiomisc.co.uk/Armstrong/armstrong.html
Audio Misc http://www.audiomisc.co.uk/index.html

Dave Plowman (News) wrote:

Eh? A 9 inch brick wall in its simplest form comprises bricks laid both
lengthwise and crosswise - ie headers and stretchers. So is approx 9"
thick.

Er, yes, and that's one brick thick - the "one brick" unit referring to
the stretcher length. A 4.5 inch garden wall is half a brick thick, but
is often wrongly described as being one brick thick.

If you want to be really pedantic the 9 inch wall (without plaster etc.)
is actually eight and five eighths thick (or 215 mm with metric bricks).
9 inch and 225 mm are the 'module sizes' including 3/8 in. or 10 mm
allowance for one mortar joint.

--
Andy

On 2008-09-27, John Rumm wrote:
Bill Wright wrote:

Yesterday the IT man came here. He rigged up two screens on one computer.
Initially the display showed the normal desktop plus wallpaper on one screen
and just the wallpaper on the other. I asked why the icons weren't present
on Screen 2. He said, "Well it's just a mirror of Screen One."
I said, "Well, I don't understand you because it isn't a mirror image, and
my point is that the icons aren't there, irrespective of whether it's a
mirror image."
"No, it's a mirror. It's a mirror of Screen One.It isn't a mirror image."
There was a period of mutual incomprehension. Of course I now know that he
was using the word 'mirror' in a way that was new to me. He meant it was a
sort of 'second copy'. Perhaps 'duplicate' would be a better word.

Sounds like the IT man was talking out of the back of his head anyway...
with a dual head (i.e. two monitor) system, the second screen as you
describe it is acting as an extended desktop. So its not a mirror, but
and extension to your current screen. You can drag icons there if you want.

That would depend how you set it up. You _can_ set up a dual head
system to display exactly the same thing on both monitors. It probably
was the default setting in this case, as it's somewhat technically simpler
to achieve.

--
David Taylor

In article , Andy Wade [email protected]
xwell.myzen.co.uk scribeth thus
John Rumm wrote:

A good example being how the the wiring regs talk about "Low Voltage"
meaning anything 500V or lower.

In the interest of the high standards of accuracy and pedantry that
readers of this group have come to expect, I'd like to point out that:

- 'low voltage' means a nominal voltage exceeding extra-low voltage
(ELV) but but not exceeding 1,000 volts between conductors or 600 volts
to earth for AC, or 1,500/900 volts for DC;

- ELV in turn means a nominal voltage not exceeding 50 V for AC or 120 V
for DC, whether between conductors or to earth.

Most people would probably not think of mains voltage as "low".

This is true. There are plenty of similar examples. The measurement of
brickwork comes to mind - a 9-inch brick wall is one brick thick, not two.


Depends whether the bricks end on...

i.e. a header....
--
Tony Sayer

In article ,
Mike Henry wrote:
That's what I'd have thought - a 'mirror' is used in IT parlance for a
site that offers an alternative source of the same downloads.

...because it is conveying the fact that changes to the first site also
happen on the mirror site. Just like when you stand at a mirror and move
your arm, the arm in the mirror moves too.

However a mirror in the visual image sense not only shows a copy of
whatever it is reflecting, but it reverses the image. If you have two
monitors next to each other, and the one on the right is NOT a reversed
reflection of the one on the left, it is ridiculous to call it a
"mirror". Call it a copy, call it a clone, but never a mirror.

Indeed - but such things never worried IT types. Rather the same as
calling all data reduction systems data compression. Only a loss less one
can truly be called compression.

--
*Welcome to **** Creek - sorry, we're out of paddles*

Dave Plowman London SW
To e-mail, change noise into sound.

On Sun, 28 Sep 2008 11:24:33 +0100, Owain
wrote:

Dave Plowman (News) wrote:
My Fluke DVM gives a warning at approx 30 volts. I've never quite worked
out why...

Anything above 30V is probably Dangerous. I think the lowest recorded
voltage for electrocution was 38V?

Owain
It's not the voltage that kills you - 15mA is all that's required (I
think)
--
Cheers

Peter

It's not the voltage that kills you - 15mA is all that's required (I
think)

Of course, but a certain voltage is required to push enough current through
your body, which has a resistance of its own.

I understand that the skin provides much of that resistance, and people's
skin resistance varies enormously. I once got a hell of a belt off a 12V
car battery. My hands were both wet with battery acid (don't ask), which
must have reduced my skin resistance to a very low level because when I
touched the terminals with my two hands the shock was amazing.

Incidentally, I think a fatal current is probably higher than 15mA. RCBs
trip at 30mA, for instance. Of course, the duration of the shock is
important, too. Again, I suspect that some people are much easier to kill
than others with an electric current, so it might not be very meaningful to
define a particular current as fatal.

SteveT

Mike Henry wrote:
In , "Dave Plowman (News)"
wrote:

In article ,
John Rumm wrote:
However, I still can't see how you can describe a second display as a
mirror unless it is at least displaying the same image... e.g. plugging

It would also have to reverse the image too, making it useless, to be
called a mirror.

Well, I could understand the phrase being used in that way for this
application. Mirror is used in a number of places in computer technology
- and does not always imply any alteration to the presentation. So a
hard drive mirror (i.e. part of a RAID system) one drive is an exact
copy of the other. A web site, could be mirrored - its content
duplicated on another server etc.

a monitor into the VGA port on many laptops would allow the external
screen to show the same as the internal - that you could call a mirror.
That's what I'd have thought - a 'mirror' is used in IT parlance for a
site that offers an alternative source of the same downloads.

...because it is conveying the fact that changes to the first site also
happen on the mirror site. Just like when you stand at a mirror and move
your arm, the arm in the mirror moves too.

However a mirror in the visual image sense not only shows a copy of
whatever it is reflecting, but it reverses the image. If you have two

That only depends on from where you are looking... after all, why do
mirrors turn images around, but not upside down? ;-)

monitors next to each other, and the one on the right is NOT a reversed
reflection of the one on the left, it is ridiculous to call it a "mirror".
Call it a copy, call it a clone, but never a mirror.

In fact, my graphics card does indeed support true mirroring on its
output if you want (and rotation). It can be handy for doing a feed to a
rear projection video projector that does not itself have a scan
reversing option.

--
Cheers,

John.

/================================================== ===============\
| Internode Ltd - http://www.internode.co.uk |
|-----------------------------------------------------------------|
| John Rumm - john(at)internode(dot)co(dot)uk |
\================================================= ================/