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Thread View: alt.folklore.computers
22 messages
22 total messages Started by b... Or feature Sat, 10 Feb 1990 04:59
Myth in relay! Urban moth?
#1308
Author: b... Or feature
Date: Sat, 10 Feb 1990 04:59
12 lines
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I have heard a number of versions of a story about a myth
flying into a relay of an early electro-mechanical computer.
The myth gets taped into the system log book.
The use of "bug" meaning computer problem is born.

Two questions:
	Can someone attest to myth in the logbook story?
	(First- or second- hand sources preferred.)

	I find it hard to believe that this was the first time
	that an insect jammed a relay.  Is this really the origin
	of this meaning of bug?
Re: Myth in relay! Urban moth?
#1309
Author: SADO... George Sadowsky
Date: Mon, 12 Feb 1990 15:05
11 lines
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I have heard Grace Hopper tell this story several times of a moth getting 
into a machine.  As I recall, she was one of the people who found the moth 
and put it in the log book.  The machine was one of the the early 
computers at the Aiken Computation Lab at Harvard, either the Mark I or 
the Mark IV, I think.

George Sadowsky
Academic Computing and Network Services
Northwestern University
(708) 491-4080
SADO...@STAFF.ACNS.NWU.EDU
Re: Myth in relay! Urban moth?
#1331
Author: j... Phil Draughon
Date: Mon, 12 Feb 1990 23:24
31 lines
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In article <37...@accuvax.nwu.edu>, My boss SADO...@STAFF.ACNS.NWU.EDU
(George Sadowsky) writes:
> I have heard Grace Hopper tell this story several times of a moth getting 
> into a machine.  As I recall, she was one of the people who found the moth 
> and put it in the log book.  The machine was one of the the early 
> computers at the Aiken Computation Lab at Harvard, either the Mark I or 
> the Mark IV, I think.

I've heard the same story from her when she gave a talk at Ft. Gordon, GA.

Actually, she didn't claim to be one of the people who found the ``bug''
but rather she tells the story of someone else doing it.

This story is truly folklore:  While an undergrad, my advisor had
occasion to actually view the particular log book, which was to the Mark
IV I think.  He says that there is no such entry regarding a moth being
stuck in a relay.

> George Sadowsky
> Academic Computing and Network Services
> Northwestern University
> (708) 491-4080
> SADO...@STAFF.ACNS.NWU.EDU

Do I know you from somewhere?

Phil Draughon
Academic Computing and Network Services
Northwestern University
(708) 491-4070
j...@acns.nwu.edu
Re: Myth in relay! Urban moth?
#1310
Author: holl... The Polymath
Date: Tue, 13 Feb 1990 19:21
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In article <37...@accuvax.nwu.edu> SADO...@STAFF.ACNS.NWU.EDU (George Sadowsky) writes:
}I have heard Grace Hopper tell this story several times of a moth getting 
}into a machine.  As I recall, she was one of the people who found the moth 
}and put it in the log book.  The machine was one of the the early 
}computers at the Aiken Computation Lab at Harvard, either the Mark I or 
}the Mark IV, I think.

I've heard the actual log book, complete with moth, now resides in the
Smithsonian Institution.  I've never been there to confirm this, however.

-- 
The Polymath (aka: Jerry Hollombe, holl...@ttidca.tti.com)  Illegitimis non
Citicorp(+)TTI                                                 Carborundum
3100 Ocean Park Blvd.   (213) 450-9111, x2483
Santa Monica, CA  90405 {csun | philabs | psivax}!ttidca!hollombe
Re: Myth in relay! Urban moth?
#1332
Author: ign... Dave Ihnat
Date: Wed, 14 Feb 1990 22:55
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In article <37...@accuvax.nwu.edu> j...@miata.acns.nwu.edu (Phil Draughon) writes:
>
>This story is truly folklore:  While an undergrad, my advisor had
>occasion to actually view the particular log book, which was to the Mark
>IV I think.  He says that there is no such entry regarding a moth being
>stuck in a relay.

Having never seen the original entry, nor having had the pleasure of attending
one of Adm. Hopper's presentations, I feel deprived.  BUT I would like to point
out that Science News, in 1989, had an article on Grace Hopper and showed, as
the front cover, a photo of the page with the moth attached.  In the article,
they discussed this event--and it was presented as factual.  Perhaps your
advisor just didn't see the right log book in a series?  I can't believe that,
if the thing was apocryphal, Science News wouldn't have had to publish a
retraction of a forged entry...
Re: Myth in relay! Urban moth?
#1311
Author: e... Ed Dekker
Date: Wed, 14 Feb 1990 23:26
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In article <37...@accuvax.nwu.edu> SADO...@STAFF.ACNS.NWU.EDU (George Sadowsky) writes:
   I have heard Grace Hopper tell this story several times of a moth getting 
   into a machine.  As I recall, she was one of the people who found the moth 
   and put it in the log book.  The machine was one of the the early 
   computers at the Aiken Computation Lab at Harvard, either the Mark I or 
   the Mark IV, I think.


An article in IEEE Spectrum a few years ago had a photo of the logbook page,
complete with the moth.

-                                                                             -
        Ed Dekker                                      ed%...@uunet.uu.net
	Software Leverage 			
	Arlington,MA
Re: Myth in relay! Urban moth?
#1312
Author: kea... John W. Keating
Date: Fri, 16 Feb 1990 06:29
19 lines
1907 bytes
In article <37...@accuvax.nwu.edu> SADO...@STAFF.ACNS.NWU.EDU (George Sadowsky) writes:
   I have heard Grace Hopper tell this story several times of a moth getting
   into a machine.  As I recall, she was one of the people who found the moth
   and put it in the log book.  The machine was one of the the early
   computers at the Aiken Computation Lab at Harvard, either the Mark I or
   the Mark IV, I think.

At lectures, Grace Hopper used to give out "nanoseconds"...  Short pieces of
wire (~ 13") that showed the distance that light traveled in one nanosecond.
I've still got one that she handed to my father at an Air Force lecture many
years ago.  Apparently, she sounds as if she is a good speaker..  Has she
done anything else interesting at any oof her lectures?
-- 
******************************************************************************
* Internet: kea...@rex.cs.tulane.edu *        REPENT!           *          *
* Usenet:   ...!pyramid!rex!keating   * The coming of the Great  * John W.  *
* Bitnet:   cs6hecu@tcsvm             *    White Handkerchief    * Keating  *
* CI$:      73737,733                 *        is near!          *   III    *
*****************************************************************************
Grace Hopper, was Re: Myth in relay! Urban moth?
#1313
Author: mcin... David McIntyre
Date: Fri, 16 Feb 1990 10:57
38 lines
2424 bytes
In article <22...@rex.cs.tulane.edu> keating@rex.UUCP (John W. Keating) writes:

>At lectures, Grace Hopper used to give out "nanoseconds"...  Short pieces of
>wire (~ 13") that showed the distance that light traveled in one nanosecond.
>I've still got one that she handed to my father at an Air Force lecture many
>years ago.  Apparently, she sounds as if she is a good speaker..  Has she
>done anything else interesting at any oof her lectures?

When I saw her lecture in the summer of '85, she still gave out nanoseconds.
She also gave one to Dave Letterman when on his show.

My favorite part was when she brought out a bottle of shampoo.  She then
read the directions out loud:

	1) Wet hair
	2) Massage shampoo into hair
	3) Rinse hair
	4) Repeat

and then said that she tried to follow the instructions once, but after
8 hours decided to get out of the shower!  She was trying to stress the
importance of clear writing in software design.

She also made a big point about not letting pointless rules and regs
get in the way of important work.  She told some story about scavenging
for important equipment in the Navy......  The lecture was for the
NJ Governor's School.  All that month I had been trying to request a
piano for the student's dorm with no luck.

Of course, immediately after that lecture they went to the science hall,
found an unused piano, and wheeled it up to the dorm!!

She is a great lecturer.  Last I heard she was not feeling well.  She
is getting on in years.

Dave "mr question" McIntyre     |      "....say you're thinking about a plate
mcin...@turing.cs.rpi.edu      |       of shrimp.....and someone says to
office : 518-276-8633		|	you 'plate,' or 'shrimp'......"
Re: Myth in relay! Urban moth?
#1328
Author: huls... rob hulsebos
Date: Fri, 16 Feb 1990 15:32
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In article <ED.90Feb...@ravel.sli.com> e...@sli.com (Ed Dekker) writes:
>In article <37...@accuvax.nwu.edu> SADO...@STAFF.ACNS.NWU.EDU (George Sadowsky) writes:
>   I have heard Grace Hopper tell this story several times of a moth getting 
>   into a machine.  As I recall, she was one of the people who found the moth 
>   and put it in the log book.
>
>An article in IEEE Spectrum a few years ago had a photo of the logbook page,
>complete with the moth.

A year ago I found a dead butterfly moth in my Unix machine. Having heard the
story of the original moth, I taped it in my own log book.

Unfortunately, half a year later the butterfly was not more than a
few particles of dust. That's why I seriously doubt whether the
original moth has 'survived' all those years in order for it to
become a legend.

-------------------------------------------------------------------------------
Rob Hulsebos == huls...@tq.ine.philips.nl Tel +31-40-785723, Fax +31-40-786114

Try to explain this to a Unix novice:
Unix character device: can only read blocks (sectors) from the disk
Unix block device: can read single characters from the disk
Re: Grace Hopper, was Re: Myth in relay! Urban moth?
#1314
Author: j... John R. Mudd
Date: Fri, 16 Feb 1990 17:05
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In article <T80...@rpi.edu> mcin...@turing.cs.rpi.edu (David McIntyre) writes:
>In article <22...@rex.cs.tulane.edu> keating@rex.UUCP (John W. Keating) writes:
>>At lectures, Grace Hopper used to give out "nanoseconds"...  Short pieces of
>>wire (~ 13") that showed the distance that light traveled in one nanosecond.
>>I've still got one that she handed to my father at an Air Force lecture many
>>years ago.  Apparently, she sounds as if she is a good speaker..  Has she
>>done anything else interesting at any oof her lectures?

>When I saw her lecture in the summer of '85, she still gave out nanoseconds.
>She also gave one to Dave Letterman when on his show.

I heard her in '87.  Still giving out nanoseconds.

>She was trying to stress the
>importance of clear writing in software design.

I agree with the philosophy, but COBOL was still overkill.

>She also made a big point about not letting pointless rules and regs
>get in the way of important work.

The quote I've got from her talk is as follows: "If you want to succeed,
do something even if it makes people mad or nervous.  If it's a good idea,
and if you've walked all around it, go ahead and do it.  It's much easier
to apologize later than get permission."

She also mentioned the clock she had in her office.  It ran counter-clock-
wise.  Her premise was that it was just a clock, it didn't matter which
direction the hands turned, it simply had to tell time.  I've been meaning
to fix a clock to do this someday.

... John
Re: Myth in relay! Urban moth?
#1330
Author: dav... James R. B. Davies
Date: Fri, 16 Feb 1990 17:07
24 lines
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In article <22...@rex.cs.tulane.edu>, kea...@rex.cs.tulane.edu (John W.
Keating) writes:
> 
> At lectures, Grace Hopper used to give out "nanoseconds"...  Short pieces of
> wire (~ 13") that showed the distance that light traveled in one nanosecond.

I saw a lecture she gave a few years ago (must have been 1987 or later) in
which she gave out both nanoseconds and picoseconds.  The latter were packets
of pepper (graciously donated by DEC).  The distance light goes in a picosecond
is about the size of a fleck of ground pepper.

She tells some great stories in her lectures, mostly about battling
bureaucracy by ignoring the rules.  Another interesting story I recall was
about a presentation she made once before she was promoted to admiral
(I don't know what rank she was at the time, but it was about Major or so),
which was made in some very high-level briefing room.  While waiting to speak,
she was told that she was the lowest-ranking officer ever to speak there.
Then she was told that she was also the first woman to speak there (this was in
the late '60s sometime, I believe).  Needless to say, she was a bit
nervous after hearing this.

Hopefully these stories have been written down somewhere.  Does anyone know
if there have been any books or articles about Admiral Hopper that give
some of these in full?
Clocks (was Re: Grace Hopper, was Re: Myth in relay! Urban moth?)
#1315
Author: g... Gerard K. Newman
Date: Fri, 16 Feb 1990 18:15
13 lines
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In article <77...@tut.cis.ohio-state.edu> John R. Mudd <j...@cis.ohio-state.edu> writes:
>
>She also mentioned the clock she had in her office.  It ran counter-clock-
>wise.  Her premise was that it was just a clock, it didn't matter which
>direction the hands turned, it simply had to tell time.  I've been meaning
>to fix a clock to do this someday.

I have a lootkcolc for a sun-3 which is a clocktool whose hands run "backwards".

Takes people a while to figure out what's wrong with it.

gkn
SDSC systems
Re: Myth in relay! Urban moth?
#1325
Author: ste... Jeri Steele
Date: Fri, 16 Feb 1990 21:11
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In article <22...@rex.cs.tulane.edu> keating@rex.UUCP (John W. Keating) writes:
>
>At lectures, Grace Hopper used to give out "nanoseconds"...  

I too saw her pass out pico-seconds(Black pepper) about 3 years ago.

>Apparently, she sounds as if she is a good speaker..  Has she
>done anything else interesting at any oof her lectures?

Yes is quite a good speaker, in fact she was awarded the Golden Gavel
award for excellence in communication by Toastmasters International
at their International conference in (I think) 1988. You might be able
to purchase a copy of that keynote speech from Toastmasters headquarters
in California.  

The speech was similar to others I had seen in front of technical 
audiences but she really stressed that Toastmasters should assist 
in educating the children of today to communicate their ideas
clearly.  Other than that Adm. Grace told of 'midnight requisitioning',
The origin of the term 'bug', and the other stories that have been 
mentioned.


	Jeri Steele
*--**--**--**--**--**--**--**--**--**--**--**--**--**--**--**--**--**--**--**--
ste...@ni.csc.ti.com   "..one person's acronym is another person's anachronism"
Re: Clocks (was Re: Grace Hopper, was Re: Myth in relay! Urban moth?)
#1316
Author: shou... Mark E. Shoulson
Date: Fri, 16 Feb 1990 22:06
30 lines
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In article <11...@ucsd.Edu> g...@ucsd.edu (Gerard K. Newman) writes:
>In article <77...@tut.cis.ohio-state.edu> John R. Mudd <j...@cis.ohio-state.edu> writes:
>>
>>She also mentioned the clock she had in her office.  It ran counter-clock-
>>wise.  Her premise was that it was just a clock, it didn't matter which
>>direction the hands turned, it simply had to tell time.  I've been meaning
>>to fix a clock to do this someday.
>
>I have a lootkcolc for a sun-3 which is a clocktool whose hands run "backwards".


Yep, I've got an actual, physical, "counter-clock" which keeps fairly good
time in the other direction hanging on my wall.  Takes getting used to.
Unfortunately, all the numbers are written on it counterclockwise and in
mirror image, making it kinda obvious.  Very cool.  If you want, I can get
anyone who wants the address of the mail-order place I got it from.

~mark
      o o     o   o             o o   o     o        o   o     o o          
              o                       o	o   o  	   o       o   	 o     	     
  o   o     o     o         o     o     o   o      o   	 o     o       	   

Mark Shoulson:  shou...@cunixf.cc.columbia.edu   shoulson@cunixc.bitnet
                {...}!rutgers!columbia!cunixf!shoulson



      o o     o   o             o o   o     o        o   o     o o          
              o                       o	o   o  	   o       o   	 o     	     
  o   o     o     o         o     o     o   o      o   	 o     o       	   
Counter Clocks (was Re: Grace Hopper)
#1318
Author: g... Kevin J Podsiadlik
Date: Fri, 16 Feb 1990 23:02
23 lines
2025 bytes
In article <77...@tut.cis.ohio-state.edu> John R. Mudd <j...@cis.ohio-state.edu> writes:
>She also mentioned the clock she had in her office.  It ran counter-clock-
>wise.  Her premise was that it was just a clock, it didn't matter which
>direction the hands turned, it simply had to tell time.  I've been meaning
>to fix a clock to do this someday.
>
>... John

Funny you should mention it.  In an '82 Buick I have owned for several years
now, the clock in the car has had the strangest tendency to reverse direction
on the slightest impulse.  Anything from a dead battery to a pothole is
capable of flipping it's "polarity".  Currently it is going clockwise, but when
it is going counterclockwise, I have to set it to the mirror image of the
correct time for the clock to be useful.  Blows my passengers' minds when
I glance at a clock reading 4:50 and say, "Oh, it's ten after seven."

Any EE majors or car buffs have any idea what the cause might be?  (I am a
EE major myself, but I am clueless on this one.)  Please Email, I am not
subscribed to rec.autos.

Kevin Podsiadlik				    g...@mentor.cc.purdue.edu
----------------------------------------------------------------------------
P.S. I don't know if my clock goes "kcot-kcit" when it runs backwards.
Nanoseconds (Was Re: Myth in relay! Urban moth?)
#1326
Author: fast... John Fast-Eddie McMahon
Date: Sat, 17 Feb 1990 00:19
19 lines
1891 bytes
In article <111...@ti-csl.csc.ti.com>, ste...@m2.csc.ti.com (Jeri Steele) writes...
:In article <22...@rex.cs.tulane.edu> keating@rex.UUCP (John W. Keating) writes:
:>
:>At lectures, Grace Hopper used to give out "nanoseconds"...  
: 
:I too saw her pass out pico-seconds(Black pepper) about 3 years ago.

The DECUS Networking SIG picked up on Admiral Hopper's story and was selling
Nanoseconds made out of Coax cable at the last couple of symposium.  They were
autographed by Adm. Hopper.

Great bribe for the folks who didn't get to go to DECUS and expect you to bring
back stuff.
--------------------------------------------------------------------------------
John "Fast Eddie" McMahon                          FAST...@DFTNIC.GSFC.NASA.GOV
Code 630.4 - Advanced Data Flow Technology Office        SDCDCL::FASTEDDY (SPAN)
NASA Goddard Space Flight Center in Greenbelt, MD                 (301) 286-2045

"Living a 9600 Baud Lifestyle in a 1200 Baud World" - R.A.J.                 
Re: Myth in relay! Urban moth?
#1333
Author: nel...
Date: Sun, 18 Feb 1990 01:48
19 lines
1598 bytes
For the Canonical answer to this discussion (I hope) of the orgin of 'bug':

----------------------------------
Oxford English Dictionary ("bug"):
  b A defect or fault in a machine, plan, or the like.  orig.  U.S.
  1889 Pall Mall Gaz. 11 Mar. 1/1 Mr. Edison, I was informed, had been
up the two previous nights discovering `a bug' in his phonograph-an
expression for solving a difficulty, and implying that some imaginary
insect has secreted itself inside and is causing all the trouble. 1935
Jrnl. R. Aeronaut. Soc. XXXIX. 43 Casting, forging and riveting are
processes hundreds of years old, and, to use an Americanism, `have the
bugs ironed out of them'. 1956 N. SHUTE Beyond Black Stump v. 138 They
worked..until the rig had settled down and all the bugs had been ironed
out. 1958 Engineering 14 Mar.  336/2 The seven-and-a-half years..was not
an excessive time to..get the `bugs' out of a new system of that kind.
----------------------------------

(Speaking of Nevil Shute, I highly recommend _Round The Bend_.)
Re: Counter Clocks (was Re: Grace Hopper)
#1319
Author: m... M.R.Murphy
Date: Mon, 19 Feb 1990 06:27
41 lines
3000 bytes
In article <75...@mentor.cc.purdue.edu> g...@mentor.cc.purdue.edu (Kevin J Podsiadlik) writes:
 >In article <77...@tut.cis.ohio-state.edu> John R. Mudd <j...@cis.ohio-state.edu> writes:
 >>She also mentioned the clock she had in her office.  It ran counter-clock-
 >>wise.  Her premise was that it was just a clock, it didn't matter which
 >>direction the hands turned, it simply had to tell time.  I've been meaning
 >>to fix a clock to do this someday.
 >>
 >>... John
 >
 >Funny you should mention it.  In an '82 Buick I have owned for several years
 >now, the clock in the car has had the strangest tendency to reverse direction
 >on the slightest impulse.  Anything from a dead battery to a pothole is
 >capable of flipping it's "polarity".  Currently it is going clockwise, but when
 >it is going counterclockwise, I have to set it to the mirror image of the
 >correct time for the clock to be useful.  Blows my passengers' minds when
 >I glance at a clock reading 4:50 and say, "Oh, it's ten after seven."
 >
 >Any EE majors or car buffs have any idea what the cause might be?  (I am a
 >EE major myself, but I am clueless on this one.)  Please Email, I am not
 >subscribed to rec.autos.
 >
 >Kevin Podsiadlik				    g...@mentor.cc.purdue.edu
 >----------------------------------------------------------------------------
 >P.S. I don't know if my clock goes "kcot-kcit" when it runs backwards.

You know, most analog clocks run counter-clockwise if you look from behind
the clock toward the glass at the front :-) I made the standard wall clock
in my lab run backwards in the late 60's just for fun. Otherwise thinking
types would nod and say "uh-huh" when they asked how and I said that I plugged
it in backwards.

I sometimes wonder how physics will be taught when clockwise has lost meaning
because all the clocks are digital. Only right and left hand rules? Or
maybe the term will be Northern Hemisphere Toiletflushwise and Southern
Hemisphere Toiletflushwise. Are toilets in the southern hemishpere built
as mirror images of northern hemisphere toilets?

Inquiring minds want to know.
--
Mike Murphy  Sceard Systems, Inc.  544 South Pacific St. San Marcos, CA  92069
m...@Sceard.COM        {hp-sdd,nosc,ucsd,uunet}!sceard!mrm      +1 619 471 0655
Re: Myth in relay! Urban moth?
#1329
Author: pur... James R Purdon
Date: Mon, 19 Feb 1990 15:24
24 lines
1810 bytes
In article <7...@ehvie0.tq.ine.philips.nl> somebody writes:
>
>Unfortunately, half a year later the butterfly was not more than a
>few particles of dust. That's why I seriously doubt whether the
>original moth has 'survived' all those years in order for it to
>become a legend.
>
Before becoming the computer weenie that I am today, I was pursuing a career
in Entomology.  For my Master's thesis I measured several hundred wasp heads,
punched the numbers onto cards and cranked them through the bowels of
statisical packages like SAS and SPSS (after some abortive futzing with APL).
The specimens I examined were on the order of thirty years of age, and nothing
more had been done to them other than sticking them on a pin and keeping them
away from dermestid beetles (which like to eat dead insects).  In the same
boxes were specimens dating from the late 1800's.  Believe me, dead insects
can last a long time, if kept away from moisture and dermestids (usually done
by putting mothballs (napthalene) or other slow-releasing insecticide in the
case).

Jim

James Purdon
pur...@cons1.mit.edu
Re: Backward Clocks (was Re: Grace Hopper)
#1320
Author: kr... Ed Krol
Date: Mon, 19 Feb 1990 15:50
11 lines
1226 bytes
kara...@husc8.HARVARD.EDU (P.J. Karafiol) writes:

>And I once had a clock that would occasionally take it into its head to start
>running backward.  Had nothing to do with polarity of the plug, time of day,
>anything that we could tell.  Pretty frightening.  But it fell off a table
>one day and died.

The synchronous motors in most clocks will gladly run either direction.
(Based on where in the sine wave you plug them in).  But there is a spring
which prevents the rotor from rotating counterclockwise.  So they 
when intact, run clockwise.
Re: Clocks (was Re: Grace Hopper, was Re: Myth in relay! Urban moth?)
#1317
Author: Edward Greenberg
Date: Mon, 19 Feb 1990 19:35
18 lines
1593 bytes
In article <1990Feb16....@cunixf.cc.columbia.edu> shou...@cunixf.cc.columbia.edu (Mark E. Shoulson) writes:
>In article <11...@ucsd.Edu> g...@ucsd.edu (Gerard K. Newman) writes:
>Yep, I've got an actual, physical, "counter-clock" which keeps fairly good
>time in the other direction hanging on my wall.  Takes getting used to.
>Unfortunately, all the numbers are written on it counterclockwise and in
>mirror image, making it kinda obvious.  Very cool.  If you want, I can get
>anyone who wants the address of the mail-order place I got it from.
>
When I worked at MicroPro, We had one of these in the room where
the programmers of WordStar 2000 were quartered.

This may explain the curious lack of success of that program.
:-) :-)

-- 
Ed Greenberg			+1 415-694-2952 (day)
uunet!apple!netcom!edg		e...@cso.3mail.3com.com
76703,1070 on CompuServe
Re: Backward Clocks (was Re: Grace Hopper)
#1323
Author: au... Joe Augenbraun
Date: Tue, 20 Feb 1990 03:17
44 lines
2969 bytes
In article <17...@husc6.harvard.edu> kara...@husc8.harvard.edu (P.J. Karafiol) writes:
> In article <77...@tut.cis.ohio-state.edu> John R. Mudd <j...@cis.ohio-state.edu> writes:
> [Grace Hopper and rubber palm tree stuff deleted]

> And I once had a clock that would occasionally take it into its head to start
> running backward.  Had nothing to do with polarity of the plug, time of day,
> anything that we could tell.  Pretty frightening.  But it fell off a table
> one day and died.

I once fixed a clock that had a fixation for running backwards.  The thing
had a very simple synchronous AC motor that worked like this:


		Electromagnet====    H========|========H
                                     +        |        -

What this is supposed to be is an electromagnet hooked up to your fine
60 Hz line current, sitting next to a permanent magnet that is mounted
on a shaft.  When the electromagnet reverses polarity, the magnet wants
to turn 180 degrees on the shaft so that the opposite polarities line
up.  The shaft would just vibrate back and forth at 60 Hz if it wasn't
for momentum.  Momentum causes the shaft to continue turning in whateverr
direction it happenned to start turning in.  Then the shaft is turning
exactly 60 revolutions per second, and if you gear it down you've got
a clock.  In order to assure that the thing started turning in the right
direction, there was actually a mechanism in this clock that would
mechanically catch the shaft and fling it in the opposite direction if
it started turning in the wrong direction.  The mechanism would just
freewheel in the correct direction.

In the clock that I fixed the flinging mechanism was broken and I fixed
it.  I've seen clocks which have a sealed motor, but I assume that its
pretty similar inside, just more integrated.

							Joe


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"Illiterate?  Write for free brochure"
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Joe "Augi" Augenbraun                   ucp: {uunet|ihnp4|rutgers}!cbmvax!augi
System Engineering                     	arpa: cbmvax!au...@uunet.uu.net
Commodore Business Machines		Phone: 215-431-9332 
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