Re: Food Prices

On Mon, 2 Jun 2025 11:29:31 +0200, Rolf Mantel <news@hartig-mantel.de>
wrote:

Am 01.06.2025 um 04:26 schrieb Jeff Liebermann:

On Sat, 31 May 2025 20:49:21 -0400, Frank Krygowski
<frkrygow@sbcglobal.net> wrote:
 

On 5/31/2025 5:07 PM, Jeff Liebermann wrote:

>

The
rest were not hard, mostly because of quirks: I've got a repair project
pending on my side porch steps; I had to align my reflecting ceiling
sundial with due north-south, and learned my house is precisely oriented
that way... etc.

 
In the distant past, I use an analog watch:
<https://www.wikihow.com/Use-an-Analog-Watch-as-a-Compass>
The tricky part is dealing with daylight savings time.
 
These days, I find a printed paper road map.  I locate two points. One
is my own location.  The other is an identifiable landmark in the
distance.  Mountain peaks work well.  Lay the map on a flat table.
Align on the map your location and the distant landmark.  True north
is printed on the map as an arrow.

>
In my region, we have several north-south lines as features:
>
Directly south of Heidelberg, the hill edges, the old Roman road, the
railway line and the motorway are all parallel North-south lines.
>
The Rhine from Speyer to Mannheim flow due North though not exactly
straight.
>
<https://maps.app.goo.gl/Y3gegeDExwwv6rTg6>

When I displayed the link on my desktop, I noticed that there was no
compass symbol or compass rose.  However, on my Android phone, just
tapping the two concentric circles in the lower right, would toggle
the compass display.  Obviously, it makes little sense to display a
compass on a desktop that doesn't rotate or move much.

At bit further to the North, the motorway A67 goes perfectly to the
North for 25km.

Perfect north?  Many years ago, before WAAS, RTK and other GPS
accuracy enhancements were available, we were using "differential
GPS".  The system featured pseudolites (ground based GPS satellites)
that would broadcast satellite corrections using the low frequency
marine navigation system.  In order for it to function correctly, the
location and altitude of the pseudolite needed to be located extremely
precisely.  I forgot the survey accuracy that was required, but I
think it was within a few cm.  I had to go through some contortions to
deal with changes in location caused by continental drift, tidal
variations, earthquakes, etc.  I also had the same problem using GPS
to check the official survey markers along my road.  I'm not up to
date on the magic currently used to correct the corrections, but I can
assure you that even the largest objects (i.e. motorways) will move
substantially.  To be fair, I doubt these movements will be noticed
using a magnetic or flux gate compass.  Certainly, nobody needs that
kind of resolution and accuracy in a hand held device.  However, I
suspect that there will be substantial changes that will be noticed
for long baseline measurements (motorway again) and long time spans
(years), especially if the motorway crosses an earthquake fault line
or lubricated feature (rivers).

Fairly inexpensive RTK products:
<https://www.sparkfun.com/gnss/rtk-surveyors.html>
1.4cm accuracy.

On a grander scale, the Rhine Rift Valley goes in a straight line
North-to-Northwest 200km (125 miles) from Basel to Bruchsal (with edges:
black Forest and Vosges in France) and then heads straight North for
another 50 miles from Bruchsal towards the end at Frankfurt / Mainz (the
Odenwald as eastern edge gives a good North-South approximation, the
western edge is less sharp).
>
Rolf

--
Jeff Liebermann                 jeffl@cruzio.com
PO Box 272      http://www.LearnByDestroying.com
Ben Lomond CA 95005-0272
Skype: JeffLiebermann      AE6KS    831-336-2558