Kern DKM1 theodolite
Peter B. Legere
Hi all,
The discussion of Wild T-2, T-3, and T4 theolodites and their rarity
sparked this:
My spare theodolite is a Kern DKM1. I had occasion to take it in for repair
recently and was told that it was a rare and desirable instrument and known
as a "mountain transit".
It is supposidly the smallest theodolite ever made.
The vertical circle is leveled with a split bubble. The instrument is a bit
confusing to use until you get used to it because the second reading
micrometer is only 20" long. The degree micrometer has 20" ticks, so you
read X degrees 20" or 40" then add the reading from the seconds micrometer.
You can estimate to about 5".
It is very nice to transport and set up because of its small size. The only
complaint I have is that the "gear ratio" of the zeroing mechanism is a bit
too high, and it is difficult (compared to my K1A) to zero or set the back
azimuth.
I use the K1A when it is windy.
I would be interested to know if any of you have one and if there are, in
fact, smaller theodolites out there. Estimations of value might be
interesting as well. Perhaps this would be the answer to the caver's
problem.
Comments from the group vis-a-vis a bullsprick (centering rod) as opposed
to an optical plummet may be interesting as well.
Peter
--
Anvil Island Design-Build
ANVIL db
If necessity be the mother of invention, then surely laziness is the
father.
Make sure you cut it good and short, you can always splice a piece in.
Daniel Daoust
ple...@mountain-inter.net,Internet writes:
>I would be interested to know if any of you have one and if there are, in
>fact, smaller theodolites out there
I think the Wild T-16 & T1-A are about the same size
You also have to love the Swiss optics!!
Daniel Daoust (GVLSA N.Y.S.A.P.L.S)
Peter B. Legere
Daniel Daoust <Daniel...@mlsonline.com> wrote in article
> I think the Wild T-16 & T1-A are about the same size
> You also have to love the Swiss optics!!
Daniel,
I have run both Wild instruments and the Mountain Transit is definitely
smaller. I can't measure it now as I havn't picked it up from the shop yet
but I would estimate the horizontal circle to be about 3" to 3-1/2" in
diameter while the diameter of the Wild instruments is probably closer to
4-1/2".
I use both my Kerns to observe the heavens and mountain climbers on the
Squamish Chief, the third largest granite monolith in the world, (after
Gibraltar and El Capitan), which towers over my home.
Peter
HoltSurvey
Hello Peter:
While surveying for portable (helicopter) seismic exploration operations in
remote parts of the Rockies, (This is in the early 80's) I used a Wild T-Zero
which was also referred to as a "mountain theodolite". It was very small, only
read to the nearest minute, and the horizontal circle doubled as a compass.
Peter Legere wrote:
>My spare theodolite is a Kern DKM1. I had occasion to take it in for repair
>recently and was told that it was a rare and desirable instrument and known
>as a "mountain transit".
> It is supposidly the smallest theodolite ever made.
<snip>
>I would be interested to know if any of you have one and if there are, in
>fact, smaller theodolites out there.
Robert A. Holt, LS
Holt Survey Associates
Woodstock, Vermont
Peter B. Legere
HoltSurvey <holts...@aol.com> wrote in article
<199806252017...@ladder03.news.aol.com>...
> Hello Peter:
>
> While surveying for portable (helicopter) seismic exploration operations
in
> remote parts of the Rockies, (This is in the early 80's) I used a Wild
T-Zero
> which was also referred to as a "mountain theodolite". It was very
small, only
> read to the nearest minute, and the horizontal circle doubled as a
compass.
> Robert A. Holt, LS
> Holt Survey Associates
> Woodstock, Vermont
WOW ! I want one!
Most of my work is done away from (easily accessable) established control.
The compass feature would be a real asset.
So you are an old seismic surveyor, eh. That is where I cut my teeth.
Peter
>
Roy A. Fletcher
Peter B. Legere (ple...@mountain-inter.net) wrote:
with editing...
: My spare theodolite is a Kern DKM1. I had occasion to take it in for repair
: recently and was told that it was a rare and desirable instrument and known
: as a "mountain transit".
: It is supposidly the smallest theodolite ever made.
I'd eliminate the word "supposedly". It is the smallest transit ever made.
When I was a student at BCIT here in Vancouver, B.C. one of the
instructors used to do a glacier survey every summer. The DKM1 went in
one pocket of his parka and a 6" tripod went in another. Other pockets
carried brandy, some tobacco and further essentials for completing a
wild-land survey. I remember reducing the data for him, and angles were
always estimated to 2.5". He knew how to use that instrument, and it
appears he was pretty good at writing up a research grant application.
The bull-prick far exceeds the optical plummet --- for doing 2d-surveys.
However, if you do a large control survey with a Kern set-up, then adjust
it with a least-squares modelling all errors, you will see that the error
residuals for dislevelment and centreing are far greater than expected.
Zeroing has always been difficult with Kern instruments.
I don't think the caver needs a natural-light (theodolite) instrument
in the dark cave. My choice would be a Brunton or Suunto compass
reading to 1/2-degree or a sextant reading to 10'. A sextant and a
calculator with a resection routine would give a very quick method
of establishing a survey network of points throughout the cave.
You have to be aware of the light source used to illuminate the
points being sighted. Move the light ten metres horizontally and
the point being sighted will appear to move as well. I was talked
into helping with a down-hole survey by some caving friends. The
first belly-crawl through an underground stream ended the spelunking
career of this claustrophobic.
Regards. RAF
Bert Ashbrook
Roy A. Fletcher <uy...@vtn1.victoria.tc.ca> wrote:
>
> I don't think the caver needs a natural-light (theodolite) instrument
> in the dark cave. My choice would be a Brunton or Suunto compass
> reading to 1/2-degree or a sextant reading to 10'. A sextant and a
> calculator with a resection routine would give a very quick method
> of establishing a survey network of points throughout the cave.
> You have to be aware of the light source used to illuminate the
> points being sighted. Move the light ten metres horizontally and
> the point being sighted will appear to move as well. I was talked
> into helping with a down-hole survey by some caving friends. The
> first belly-crawl through an underground stream ended the spelunking
> career of this claustrophobic.
>
> Regards. RAF
Roy,
Lensatic compasses and clinometers (Suunto or Sisteco/Silva brand) are
exactly what we use. Until 10 or 15 years ago cavers used pocket transits
(Brunton and other brands) but the Suuntos are much more rugged and
waterproof.
Common wisdom (among cavers!) is that theodolites are to be avoided because
lots of short shots on the order of 3-5 feet are common in tight passages.
Small station position errors on short shots leads to relatively large
angular errors, which are cumulative. Also theodolites tend to be more
expensive, more bulky, and more fragile than Suuntos.
Wet bellycrawls can be quite pleasurable when the water's warm. It's the
snow runnoff streams that'll get you. What a way to introduce someone to
caving!
Bert Ashbrook
akmainiac
> Hello Peter:
> While surveying for portable (helicopter) seismic exploration operations in
> remote parts of the Rockies, (This is in the early 80's) I used a Wild T-Zero
> which was also referred to as a "mountain theodolite". It was very small, only
> read to the nearest minute, and the horizontal circle doubled as a compass.
> >My spare theodolite is a Kern DKM1. I had occasion to take it in for repair
> >recently and was told that it was a rare and desirable instrument and known
> >as a "mountain transit".
> > It is supposidly the smallest theodolite ever made.
> >I would be interested to know if any of you have one and if there are, in
> >fact, smaller theodolites out there.