Uploaded November 2017 | Updated September 2026, 1 week ago
8 in per mile squared is the allegedly drop of a horizontal line, on the globe model of the Earth. In this video I will show if I using a theodolite can measure this drop. The first part of the video deals with finding first hand accurate height measurements for the observation point and for Turning Torso, the result can be seen at 11:50
Table of contents:
Height of observation point, 1:08
Ground height at Turning Torso, 2:43
Height and dimensions of Turning Torso, 3:55
Calculations of drop on a globe Earth, 7:27
Calculations of refraction on a globe Earth, 7:50
Theodolite observation, 8:36
Error of measurement, 11:15
Result, 11:50
As you might notice this footage was recorded in windy conditions which caused the theodolite to move a little bit up and down. It would have been better to do the observation in less windy weather, but the visibility this day was exceptional clear, and most other days it will not be this clear. So I favored clear bouncy footage over blurry still footage.
The preferred way to measure with a theodolite is to do several observations turning the theodolite 180 degrees to minimize errors. But since I thought the error from the wind would be larger I chose not to, and also to simplify the observation for a later video. Looking back, I should properly have done more observations, since the uncertainty of intersection caused by the wind, could be averaged to minimize the error.
When measuring with a theodolite it is also important to have it calibrated on a regular basis. Since I just bought this theodolite and it had been stored away for some time, it properly has not been calibrated for a long time. I should have followed the prescribed method for calibrating the theodolite before using it, but I didn’t. Testing the theodolite afterwards I can see it has a small error, and also since it does not have an electronic angle reader there is also a small error from how precise I can position the telescope. From my testing this might lead to an error as large as 8m/26ft when used over a distance of 29.14km/18.11mi. Using a well calibrated professional electronic theodolite will likely reduce this possible error significant.
When I combined the estimated error of measurements I used a loose simple summation, and not the proper scientific way in order to keep the video as simple as possible.
Theodolite model: Geo-Fennel FET 500
Link to manual for the theodolite: geo-fennel.de/uploads/tx_produkte/FET_500.pdf
The observation with the thodolite was done on the 27th of October 2017.
Altimeter measurements were done from March to August 2017.
Weather conditions from https://www.dmi.dk/vejr/arkiver/vejrarkiv/:
Highest temperature of the day: 11 °C
Average temperature of the day: 10 °C
Lowest temperature of the day: 7 °C
Humidity: 86 %
Air pressure: 1015 hPa
Highest wind speed: 17 m/s
Highest wind speed, average 10 min: 13 m/s
Direct sunshine: 2 hours
#TurningTorsoFlatEarth
8 in per mile squared is the allegedly drop of a horizontal line, on the globe model of the Earth. In this video I will show if I using a theodolite can measure this drop. The first part of the video deals with finding first hand accurate height measurements for the observation point and for Turning Torso, the result can be seen at 11:50
Table of contents:
Height of observation point, 1:08
Ground height at Turning Torso, 2:43
Height and dimensions of Turning Torso, 3:55
Calculations of drop on a globe Earth, 7:27
Calculations of refraction on a globe Earth, 7:50
Theodolite observation, 8:36
Error of measurement, 11:15
Result, 11:50
As you might notice this footage was recorded in windy conditions which caused the theodolite to move a little bit up and down. It would have been better to do the observation in less windy weather, but the visibility this day was exceptional clear, and most other days it will not be this clear. So I favored clear bouncy footage over blurry still footage.
The preferred way to measure with a theodolite is to do several observations turning the theodolite 180 degrees to minimize errors. But since I thought the error from the wind would be larger I chose not to, and also to simplify the observation for a later video. Looking back, I should properly have done more observations, since the uncertainty of intersection caused by the wind, could be averaged to minimize the error.
When measuring with a theodolite it is also important to have it calibrated on a regular basis. Since I just bought this theodolite and it had been stored away for some time, it properly has not been calibrated for a long time. I should have followed the prescribed method for calibrating the theodolite before using it, but I didn’t. Testing the theodolite afterwards I can see it has a small error, and also since it does not have an electronic angle reader there is also a small error from how precise I can position the telescope. From my testing this might lead to an error as large as 8m/26ft when used over a distance of 29.14km/18.11mi. Using a well calibrated professional electronic theodolite will likely reduce this possible error significant.
When I combined the estimated error of measurements I used a loose simple summation, and not the proper scientific way in order to keep the video as simple as possible.
Theodolite model: Geo-Fennel FET 500
Link to manual for the theodolite: geo-fennel.de/uploads/tx_produkte/FET_500.pdf
The observation with the thodolite was done on the 27th of October 2017.
Altimeter measurements were done from March to August 2017.
Weather conditions from https://www.dmi.dk/vejr/arkiver/vejrarkiv/:
Highest temperature of the day: 11 °C
Average temperature of the day: 10 °C
Lowest temperature of the day: 7 °C
Humidity: 86 %
Air pressure: 1015 hPa
Highest wind speed: 17 m/s
Highest wind speed, average 10 min: 13 m/s
Direct sunshine: 2 hours
#TurningTorsoFlatEarth
