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I write, therefore I am

With this variation on a famous statement by the philosopher Descartes, I would like to express that the act of writing about what happens in my life is important to me.

Thursday, April 22, 2021

GOGBOT café, яєαℓιту ιѕ ѕуηтнєтι¢

I watched this GOGBOT cafeé on YouTube. It has talks by: Followed by video screening of Kesson live coding + AI generated visuals based on a sound recording of Chebedajha (aka Jeannetta Petrik).

Tuesday, April 20, 2021

Groot Peter

Conny and I walked to the shopping center called Winkelcentrum Zuid to visit some shop and way home we went to see the marke stone Steen bij Groot Peter (33.34-05). This a replica that is placed on September 16, 2016 in the North East corner of the intersection of Wesselerbrinklaan (runing North-South), Het Bijvank (on the West). and Het lang (on the East). The original marke stone was in the middle of Wesselerbrinklaan just South of the intersection . Behind the stone (as seen from the center of intersection) there are a number of oak trees that belonged to a farm called Groot Peter. The kadaster of 1832 shows a farm called Peters at that location. Often when a son of farmer would start a new farm near the farm of his father, the names of the farms were prefixed with the words Groot (big) for the original farm and Klein (small) for the new farm. This is probably how the name Groot Peter came into existence. The adjective Klein and Groot are also found in surnames from people coming from this region, because for a long time people were named after the farm where they came from instead of with a surname or patronym.


Monday, April 19, 2021

Hexagon puzzel

I gave Conny a small wooden puzzle as a present. In the Netherlands it is sold under the name Hexagon puzzel. It is produced in China, Yunhe County, Lishui City. The product model is XC-808 with the name Interesting Changeful Puzzle. She wanted to know how many solutions it had. After some wrong tries (including not realizing that the pieces could not be used upside down), I arrived at the conclusion that there are 4702 solutions excluding solutions that are the same with respect to rotation of the whole solution. I took the btc24_to_ec.cpp program, which I developed for the Beat the Computer No. 24 puzzle, and made it into a more generic program for puzzles on a hexagon grid (with either hexagons or triangles), calling it hexagon_to_ec.cpp. The command line arguments 1 --flat need to be used for the Hexagon puzzel. The output is fed into an exact cover solver and postprocessed with a small program that makes a letter string of each solution. Below all the solutions are shown in a random manner or can be traversed using the buttons. (The 'a' piece is always placed in the same orientation.)

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Sunday, April 18, 2021

In full bloom

Today, finally, all the flowers of our magnolia opened. It is almost three weeks ago that the first flowers opened. The temperature has been quite low for the time of the year in recent weeks, even dropping below zero degrees Celsius, causing some of the flowers to turn brown. But this afternoon all the flowers had opened and you could smell the nice scent of the magnolia in the garden.

Saturday, April 17, 2021


Conny and I went walking through the adjecent forests Snippert and Het Haagse Bos. At one point we came to a location where the path was submerged in water and we wondered whether there was a way to get to the other side when there appeared a woman on the other side, who wanted to get to our side. After some searching, we found signs of a small path leading around the area, which seemed to have been used for some time, because at one place there were three wooden trunks laid side by side over a water filled ditch. During our trip we found two two marke stones:
  • At 14:43, Steen tegen het ossenschot (20.32-01).
  • At 15:25, Steen aan 't Haagerbrook (20.32-02).

Thursday, April 15, 2021


I have been thinking about genealogy the last days. Yesterday evening, I spend some time adding some data to WikiTree based on some data from the Dutch resource site: WieWasWie. First of all, I realized that the WikiTree is American centered because, for example, the concept of a middle name is not universal. Here in the Netherlands, we do not have the concept of a middle name. Someone can have one or more firstnames, where having four firstnames is not rare. (Not to talk about a generation name in some Asian countries.) The second thing I realized is that although it is possible to add sources, it is not a source based approach. During the night, I thought about an algorithmic approach to genealogy, where the 'family tree' is constructed based on a collection of records. This morning, I spend some time transcribing the marriage certificate of Leonardus van Bragt and Margaretha Dorothea Faase. The result of this is:
      Heden den Zevenden Mei ACHTTIENHONDERD
    NEGENTIG, verschenen voor ons, Ambtenaar van den burgerlijken stand der gemeente
    Schoten in het huis derzelve gemeente,
    ten einde een huwelijk aan te gaan:
    Leonardus van Bragt
    oud drie en twintig jaren, van beroep bloemkweeker
    geboren te Velsen en wonende te Velsen,
    meerderjarig zoon van Willem van Bragt van beroep
    bloemkweeker en van Maria Elisabeth Alders, zonder
    beroep, beiden wonende te Velsen, ter Eene

    en Margaretha Dorothea Faase
    oud vier en twintig jaren, van bezoep zonder,
    geboren te Bloemendaal en wondende te Schoten,
    meerderjarige dochter van Jacob Faase, van beroep
    bloemkweeker, wonende te Schoten en van Petronella
    Catharina van der Veld, overleden, ter Andere Zijde,

    van welk huwelijk de vereischte afkondiging zonder stuiting hebben plaats gehad op
    Zondagen, den Twingtigsten en Zeven en twintigsten April deze jaar
    binnen deze gemeente en binnen de gemeente Velsen

      Door de aanstaande echtgenooten zijn ons overgelegd:
    1º Het bewijs, dat de huwelijksafkondigingen zonder Sluiting
    zijn afgeloopen te Velsen, 2º hunne geboorte-akten,
    3º de akte van overlijden der moeder van de bruid, 4º het
    bewijs dat de bruidegom heeft voldaan aan de wet op
    de Nationale Militie.
    Voorts verklaarden de ouders van de bruidegom en de
    vader van de bruid, die mede voor ons verschenen, hunne
    toestemming tot het aangaan van dit huwelijk te geven.

      Waarna wij hun in het openbaar hebben afgevraagd, of zij elkander aannemen tot
    echtgenooten en getrouw de plichten zullen vervullen, welke door de Wet aan de huwelijken
    staat verbonden zijn; hetwelke door hen toestemmend beantwoord zijnde, hebben wij in naam
    de Wet verklaard, dat zij door het huwelijk zijn vereenigd. In tegenwoordigheid van:
    Franciscus Faase, oud zestig jaren, van beroep bloemkweeker,
    wonende te Bloemendaal, oom-; Johannes Franciscus
    Faase, oud een en zestig jaren, wonende te Schoten, van be„
    roep bloemkweeker, oom-; Cornelis Hendrik van Looij, oud
    acht en veertig jaren, van beroep winkelier, wondende te Bloe„
    mendaal, behuwdoom van de echtgenoot en Johannes
    Alders, oud een en vijftig jaren, van beroep uurwekma„
    ker, wonende te Schoten, oom van den echtgenoot.

      En is hiervan door ons opgemaakt deze akte, welke na voorlezing, door ons, de com„
    paranten en de getuigen is ondertekend.

Where I have marked all the handwritten parts in italics. The ordinal indicator in the certificate has two dashes instead of one in the above transcription. I have used the Double Low-9 Quotation Mark as the two commas that indicate a continuation with the next line. Something that nowadays is usually done with a dash. This already shows some of the problems with transcribing documents. And, so far, no one has verified the transcription. In a distributed information system, you would at least have some mechanism to sign a transcription to indicate who did the transcription and who reviewed it with digital signatures. And there is also the problem that there could be multiple interpretations of the document and that one would like to record variants.

Next, I spend some time thinking about a way to represent all the data from the above marriage certificate in some form of JSON. Most of the information is already included in the page, but, for example, the information about the witnesses is not included. The extra information could be used to calculate the probability that two people mentioned in different records are indeed one and the same person. The information is also not in a computer readable form, although, I expect that it is retrieved from some kind of database with a welldefined structure. It would be nice if there is some kind of REST API to query this database. Below an example of how the information in the marriage certificate could be represented in a way that could be processed by a means of an application that constructs a family tree.

{ "source":{
    "Document type":"BS Huwelijk",
    "Institution name":"Noord-Hollands Archief",
    "Institution place":"Haarlem",
    "Collection region":"Noord-Holland",
    "Registration date":"07-05-1890",
    "Certificate place":"Schoten"},
           "name":"Leonardus van Bragt",
              "name":"Willem van Bragt",
              "name":"Maria Elisabeth Alders",
        "bride": {
           "name":"Margaretha Dorothea Faase",
               "name":"Jacob Faase",
               "name":"Petronella Catharina van der Veld",
            "name":"Franciscus Faase",
            "relationship":{"type":"uncle", "of":"bride"}},
            "name":"Johannes Franciscus Faase",
            "relationship":{"type":"uncle", "of":"bride"}},
            "name":"Cornelis Hendrik van Looij",
            "relation":{"type":"uncle through marriage", "of":"groom"}},
            "name":"Johannes Alders",
            "relation":{"type":"uncle", "of":"groom"}}]}}
      {"person":"Franciscus Johannes Faase", "signature":"bd078fe...."}]}

As is often the case with a more formal approach to solving a problem is that it requires a lot of more effort (and a different kind of mindset) than a more informal approach. Also it requires a greater attention to details of the people involved. And we should not forget that reality is always more complex than one thinks at first and that it is thus very difficult to develop a formalism which covers all cases.

Wednesday, April 14, 2021


Tuesday, April 13, 2021


Sunday, April 11, 2021

Het Haagse Bos

Because last week, the German governments demands all negative test for COVID-19 for people crossing the border from the Netherlands, Conny and I decided to halt our search for border poles and instead search for some marke stones and go for a walk through the forests known as Het Haagse Bos where a marke stone can be found. We found the following marke stones:
  • At 12:34, Steen aan de kamp in het veld (19.33-02).
  • At 12:44, Steen op het Wachtveld (19.32-06).
  • At 12:47, Steen bij Hendrik Beumer (19.32-01).
  • At 13:24, Snippertsteen (19.20.32)
The last stone is there were the marke Lonnekermarke, Lossermarke and Luttermarke meet.

Wednesday, April 8, 2021


After I came home from work, I worked on a program (at first based on hexagonnum.cpp) to calculate the number of convex polygons that can be constructed from a given number of equal sized, equilateral triangles. When it did produce a sequence that looked correct, I entered it in On-Line Encyclopedia of Integer Sequences. To my surprise, it did not return any results. Instead of suggesting it as a new sequence, I took the advice to first search the encyclopedia. I came along sequence A096004: Number of convex triangular polyominoes containing n cells, which looked like describing what I had calculated. When I compared it with my own sequence, I discovered that the value for fifteen triangles/cells was different. After some debugging, I discovered a bug in my program and after fixing it, it returned the same sequence.

Wednesday, April 7, 2021


There was about 1cm of snow on my car this morning. The roofs of houses, plants and some place on the ground were also covered with snow. In the past days, there were a lot of winter showers with snow and hail alternating with sunshine, several times even at the same time. On Monday evening and Tuesday morning, there was also some snow on roofs and some other areas. Todaym we also had some rain showers, but later in the afternoon, again some hail.

Monday, April 5, 2021


During the Easter weekend, Conny and I went to Voorthuizen where we rented hotel room at holiday part De Boshoek. We arrived on Friday after we had searched for 'border stones' of the city Apeldoorn. In 1750 the border of the municipality of Apeldoorn was established with wooden poles. Around 1794 the 26 wooden poles were replaced with stone poles. Most of these stone poles have since been removed. Along the entry roads, stone name signs of the city have been placed. It is these name signs, on the East side of the city, we have searched. Conny used the report (in Dutch) Speurtoch naar grenspalen and Google streetview to record the location of these in Google maps. Later, I discovered that some of these poles and also some others are indicated on various topographic maps.

On Saturday, we visited the Green Cathedral, which I visited before on August 25, 2016. We also walken around castle Geerestein just North of Woudenberg.

Yesterday, we continued our search for the name signs. This time on the West of the city. We also entered the crown domain Het Loo where we found another name sign just besides one of the original border stones with the letter A and E on opposing sides. We continued walking through the woods, which we felt were rather boring. Today, we decided to go home early and not visit any places on the way home, because rain, wet snow, hail, thunder and strong winds were predicted. We did see some wet snow on the way home.

Thursday, April 1, 2021

De Poppe

Conny and I continued our search for border poles. We walked in an area called De Poppe. We encountered the following border stones:
  • At 14:04, pole 17.
  • At 14:07, pole 17-I.
  • At 14:59, pole 17-II.
  • At 15:04, pole 18.
  • At 15:20, pole 20.
  • At 15:41, pole 20-II.
  • At 15:46, pole 20-III.

Wednesday, March 31, 2021

24.4° Celsius

The temperature at Twenthe Airport went up to 24.4° Celsius, which breaks the previous record of 23.7° for the temperature on this date in 2017. The predicted temperature according to the prediction at the start of the day, was 21.8° Celsius.

Tuesday, March 30, 2021


Monday, March 29, 2021

Idoneal numbers

On February 5, 2019, I wrote about hexagon numbers. Today, I discovered that the numbers I found, are sequence A229757 in the On-Line Encyclopedia of Integer Sequences. With the sequence, there are references to two publications: Reguläre Dreieckpflasterungkonvexer Polygone.and Tiling Convex Polygons with Congruent Equilateral Triangles by Eike Hertel and Christian Richter. The second paper is an extension of the first one with respect to proofs. The numbers for pentagons the numbers are related to the Idoneal numbers. It is not known if there are more idoneal numbers than the one that are known, but there are no more if generalized Riemann hypothesis is true. As a pentagon can often be changed into a hexagon by removing, one would expect that both sequence match with an offset of one. That is indeed the case for many numbers, but not all.

First two flowers

The first two flowers of our magnolia have opened today.

Sunday, March 28, 2021

Revisiting Coevorden

Conny and I revisited Coevorden to look for border poles we had missed on previous visits after I created a GPX file with waypoints using the ArcGis viewer and downloaded this (through Google Drive) to OsmAnd on my Galaxy Tab 3 tablet. The weather was a bit rainy for most of the time. We had brought some devices to remove weeds and brambles. We encountered the following border poles:
  • At 13:05, pole 133-I again.
  • At 13:10, pole 133-II. Almost submerged.
  • At 13:19, pole 134.
  • At 13:25, pole 134-I again.
  • At 13:30, pole 134-II again.
  • At 13:35, pole 135 again.
  • At 13:36, pole 135-I. (Plate says 135 with carved I.)
  • At 13:39, pole 135-II.
  • At 13:44, pole 135-III.
  • At 13:45, pole 136.
  • At 13:52, poles 137 and 137-I again.
  • At 15:15, pole 147-I again.
  • At 15:17, poles 147-II (N) and 147-II (D) again.
  • At 15:21, pole 148 (D) again.
  • At 15:22, pole 148 (N) laying in a ditch.
  • At 16:25, pole 152-I (D). Almost submerged.
We searched for about a quarter of an hour for pole 133-III, cutting away weeds and brambles, but failed to locate it. To our horror, the area where poles 145 to 146 stood is now a construction site with a large warehouse like building surrounded by parking lots (still under construction). It seems the poles have been removed. We also searched for poles 151-VI (D) and 152-I (N). It looks like these two have disappeared.

Saturday, March 27. 2021


Wednesday, March 24. 2021


Tuesday, March 23, 2021

Border changes around Losser

I continued working on a KML file (to be viewed in Google Earth) about the border changes just North of Losser. I spend a long time determining the position of the border poles 8 to 11 using the available data. The positions I have chosen, are inferred from cadaster data from now and 1832, do not perfectly match with the positions I calculated from the positions of the assurance stones and the map by Otto Koolmann. They are about seven meter off. My GPS measurements of the locations are probably not very accurate. The possibility that the border poles have been moved between the two dates, should not be excluded, because it is known that the poles were washed away several times by the meandering river. I do not know if it is possible to get more accurate GPS locations (without having to spend hunderds of Euro's). I found the ArcGis viewer where you can get GPS coordinates on a recent topographic map. It did show a dot at the location of one of the assurance stones. The GPS locations where close to the one that I measured myself. I used the viewer to adjust the GPS coordinates of some of the border stones along the current border. The KML file contains the following folders:
  • Losserbrugge: Some border poles based on a map just North of border pole 6 where there was a neutral area.
  • Koolmann: With the position of the assurances poles and the positions of the border poles based on the map of Otto Koolmann around the start of the twentied century.
  • Before 1949: With border poles on the border before April 23.1949.
  • 1949 - 1963: With (wooden) border poles for the border from April 23, 1949 till August 1, 21963.
  • After 1963: With some border poles placed after August 1, 1963.
  • From 1988: With some border poles that were only shown on a map after 1988.
Besides the folders there are also some border poles that were used during periods before and after the annexation.

Sunday, March 21, 2021


This morning, I was looking through the book Grensgang: een historische reis langs de randen van Overijssel (in Dutch) written by Jan ten Hove (starting from the back). It is about the history of the borders of Overijssel described as a trip along the border. On page 149, I found a reproduction of a drawing by Otto Koolmann about the 'Verzekeringsstenen', which could be translated (from Dutch) to English as 'assurance stones'. They are at a place where a turn of the border with Germany was established in the middle of the river Dinkel. To define it, on each side of the river two poles were placed, where the crossing point of those poles defined the exact position of the turn in the border. However, the river, as most rivers, was meandering, and over time some of the stone poles, (mostly on the German side) were washed away. To overcome this problem, four new stones were placed at a larger distance of the river as kind of assurance. Hence the name of these poles. We realized that the two unmarked stones we found last Thursday might have been two of the four verzekeringsstenen. We also read some account of some unmarked stones on the other side of the river. This afternoon, Conny and I decided to have a closer look and try to determine the location of the stones with GPS. We encountered the following stones and border poles:
  • At 13:17, unmarked stone on the former Dutch side at approximately 52°17'00.5"N 7°01'30.6"E.
  • At 13:40, unmarked stone on the former Germany side at approximately 52;deg;17'01.0"N 7°01'40.2"E.
  • At 13:42, unmarked stone on the former Germany side at approximately 52°17'03.3"N 7°01'39.5"E.
  • At 13:46, pole 11-II.
  • At 13:52, pole 11-III.
  • At 13:56, pole 12.
  • At 14:25, unmarked stone on the former Dutch side at approximately 52°17'01.7"N 7°01'30.4"E about 15 to 20 meters to the North of the other.
At home, I used the coordinates to locate the position of the orginal four border poles (with the numbers 8, 9, 10, and 11 of the pre-1949 border) using the drawing by Otto Koolmann. I tried to match these with the cadaster map of 1832 from the area, but failed to make an exact match. The article (in Dutch) De Verzekeringsstenen by Aafke de Wijk suggests that the two stones on the former Dutch side of the river might be two of the original border stones. I think that is not very likely. Conny send me a link to the article Loakgang langs de Markestenen en Rijksgrenzen van de Marke Losser, which was published in Oet Dorp en Marke with some more information about the part of the border we visited. In it we also read that the location were we parked our car last Thursday has a history that goes back to the fourteenth century and that just North of border pole there used to be a neutral area where border disputes were resolved.

Saturday, March 20, 2021

Parsing workshop

This afternoon, at 14:00 (CET), I gave the workshop A modern approach to parsing programs as part of the CyberSaturdays of TkkrLab. For some unknown reason, the mircophone of my headset was not working, and I had to use a MacBook of someone else. My intention of the workshop was that everyone, no matter their level, would get something out of the workshop. But afterwards, I felt that I had failed this objective. I realized that in the past weeks, I spend a lot of time working on the materials and the programs, instead of thinking about the workshop itself. I think that my previous experience would be enough to just improvise during the workshop, but I am afraid I was blinded by my pride to realize that giving a workshop online is a quite different. I think, I should have taken some time at the start to see the attendees and ask them about their experience level. I also think, I should have started with an example of parsing an expression and evaluating its value and use this as a starting point to explain everything that is needed to parse it. Something, like I start doing at 22:22 of the presentation. Taking the normal priority rules used in numerical expression, I could have explained the use of priorities and how you could use a formal grammar to describe it.

And then only explain something about the history of parsing and how I started developing IParse and that I took a very different approach from the traditional way of developing parsers. I remembered, for example, that IParse cannot parse all Context-Free Grammars (CFG), but that this has never been a problem for all the practical grammars that I have encountered in the past 20 years. Apparently, grammars used for programming languages are more limited than the general class of CFG, probably due to what can be easily comprehended by us humans.

Thursday, March 18, 2021


Conny and I spend some time walking near Losser, searching for border poles. We ended up walking a part along a walking path called Graafschapspad which was flooded at certain locations probably because of the high water level in the Dinkel river. We encountered the following border poles:
  • At 11:39, pole 4.
  • At 12:25, pole 5-II, which is almost submerged.
  • At 12:29, poles 5-III and 6.
  • At 13:22, pole 11.
  • At 13:30, unmarked border stone.
  • At 13:32, unmarked border stone.
  • At 14:25, pole 6-I.
  • At 14:31, pole 5-I, which is almost submerged.
There are some poles between pole 4 and 5-I, but they are between a nature reserve (on the Dutch side) and private property (on the German side). There are also some poles between 6-I and pole 11 that are along farm fields. When walking back, we looked if we could locate these from the path we walked. I took some tele pictures from places where we thought to see a pole. At home, I did discover a pole in one of the pictures. I think it is either from pole 7 or 7-I. At home, I spend a long time investigating all kinds of maps (from the Dutch websites: topotijdreis, PDOK viewer, and HISGIS, horigheid) because there has been some border changes after the second war. An area of about one square kilometer was annexed in 1949 and for the most of it returned in 1963 except from some farm field on the east bank of the river. I studied some old maps and also discovered something about four poles, numbered 8, 9, 10, and 11, that were placed two by two on both sides of the river as shown on a map from 1832. In the past centuries the river often changed it course and now is east of the location where these poles where placed. I created a KML file (to be viewed in Google Earth) with my findings so far, which I probably will update again. It seems that one pole has survived. In the area an artwork with the name De landmeter (the surveyor ) has been placed. We have not visited this.

Monday, March 15, 20210


Sunday, March 14, 2021

Passing by

Conny and I drove along ten of the cities billboards that usually show information about events in the coming months, but till the end of the month act as an outside exhibition, called Passing By with 19 reproduction of art works of just as many graduates from the AKI from 2020. These are the graduates as we encountered them on our route: Back at home, I made a map of the route we took.

It was a windy day with rain and sunshine quickly following each othere, a typical rainbow day. We saw two rainbows at different locations.


Saturday, March 13, 2021

Dell Latitude D630

This afternoon, when I prepared our Dell Latitude D630 to be used by Andy, I accidently plugged in the wrong power plug, one that has a slightly larger center plug. After some time, Andy pointed out to me that the battery light was blinking. When I plugged in the correct power plug, it kept on doing so. I concluded that I must have destroyed the charging port. I tried to open it, which took some effort, but I was not able to get to the charging port. Because Andy is the only one who has been using it in the past years, I decided to leave it as this and maybe dispose of it. I did take out the 2Gbyte memory module and the harddisk.

Friday, March 12, 2021

Game of Thrones: Season 8

This evening, we watched Games of Thrones (season 8). We watched the previous seasons in the past months. often not more than watching three episodes per evening and about five episodes per weekend. When we, after having seen four episodes, discovered that there were only two left to finish the series, we decided to watch the last two as well. I remembered that many people were disappointed when watching the final episode when it was broadcasted. I also recall that it was shown in movie theathers here in the Netherlands. I can now understand why some people were disappointed. It felt a little as an epilogue after the first third of the episode. But it does feel like in accordance with what George Martin might have had in mind to finish this series.


Thursday, March 11, 2021


Conny and I walked continued our search for border poles. This time we walked near the Haarmühle, which is a watermill just over the border with Germany. The current mill is from 1619. The previous watermill was from 1331. There is a mentioning of the name Haremole from 1188, which suggests that there was already some watermill in that periode. The current watermill was restored in 1988. Since 2000 is also used to produce electricity, We encountered the following border poles:
  • At 10:12, pole 835-C.
  • At 10:17, pole 835-B (stone 18).
  • At 10:28, pole 836-A.
  • At 10:29, pole 836-B.
  • At 11:06, pole 837-E (stone 21).
  • At 11:11, pole 837-F (stone 21A).
  • At 11:14, pole 837-G.
  • At 11:20, pole 837-H.
  • At 11:28, pole 837-J (stone 22).
  • At 11:37, pole 838 (stone 23).
  • At 11:50, pole 838-A.
  • At 12:00, pole 838-B (stone 24).
  • At 13:11, pole 837-C.
  • At 13:13, pole 837-B.
  • At 13:16, pole 837-A (stone 20).
  • At 13:20, pole 837.

Wednesday, March 10, 2021

RD 340306

This evening, I saw a triangle with the letter R.D. in an atlas at the location where we searched for the Dutch trigonometric point 340306. I tried to find some more information about it on some geocaching sites and on one of the sites, I found a link to an excel sheet with information about all Dutch trigonmetric points. To my surprise, I found that point 340306 has been cancelled. On PDOK viewer it is now shown when the RDinfo, Punten dataset is selected. Information about this can be found on RD-coördinaatpunten als open data (in Dutch) when entering the number below 'Puntnummer ingeven'. It gives the following information about the various points involved:

From the drawing, I understand that the distance between Nr 13 and Nr 14 is 156.9, and that 9.5 perpendicular from 66.0 from Nr 13 to Nr 14 is the location of Nr 11 and Nr 12. The drawing seems to suggest that Nr 14 is at the border, but the location is actually in Germany, which matches the description that talks about 24.8 meter South of the forest path.


Tuesday, March 9, 2021


Since just less than a week, non-essential shops are allowed to open again in the Netherlands for customers who have made an appointment in advance. About a week ago, I made an appointment to visit the charity shop Het Goed between 16:00 and 16:30. At 16:23, I bought the book 1001 Boeken die je gelezen moet hebben edited by Peter Boxall, written in Dutch and published by Librero Nederland b.v. in January 2017, ISBN:9789089988058, from for € 3.95 at the store. I also made some donation to express my gratitude and to compenstate for their losses during the lock-down. I used to visit this shop about twice a week and I might have spend the donated amount in case they would have been open.

Saturday, March 6, 2021


Conny and I continued our search for border poles. We walked through an area in Germany where all the roads are called Nork. We encountered the following border poles:
  • At 15:49, pole 834-F.
  • At 15:53, pole 834-G.
  • At 16:25, pole 835-A, stone 17.
  • At 17:16, pole 835, stone 16.
We did see pole 835B from a distance in the fields. From there we walked on the right side of the spring Zoddebeek, which in Germany is called Zoddebach. We got a little lost and had to cross the spring at a weir


Wednesday, March 3, 2021


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