I can’t stop thinking about this. I understand that if the world was a perfectly smooth sphere this would be the case, but surely a normal athletic field is flat… or is it?
One thing that is common, if not recognized by most people is how much the curvature can affect property acreage.
According to one surveyor, in places where the property lines are along lines north to south a mile apart and lines east to west a mile apart, it is unusual for two “sections” or farmland or ranchland to be the same area even though they are all approximately one mile by one mile.
Note that the word “sections” can have two different meanings.
One is a unit of measure of area - it is 640 acres. If someone has a section of land, it may be a mile by a mile but it may also be a half mile by two miles.
The other is as something like an address on a property map or like a rough description of a plot of land that may or may not be square and may be much more than 640 acres. One example would be in old Spanish land grants that have been split into large parcels. They are called sections, but are rarely square or 640 acres.
I think a real field would be surveyed and leveled so that at every point the surface would be perpendicular to a plumb bob. So geometrically it would be a section of the Earth’s spherical surface, not a plane. However I doubt that any real life 400 meter athletic field would be surveyed to an accuracy where the difference between a spherical field and a planar one would be of any significance. If the Earth were a perfectly smooth sphere 4000 miles in radius and a perfectly flat rod 400 meters long were set down on it, each end of the rod would be about 1/8 inch above the ground.
Here in flat, boring, grid-mapped Kansas, a section is indeed a mile by a mile.
A half mile by two miles is two half-sections. Obviously, YMMV.
I read somewhere (no cite) that they had to take the curvature of the Earth into account when planning and building the Golden Gate bridge, but they don’t do that when building a road on flat ground (Kansas has been mentioned, but they schould have mentioned the Laufenburg Hochrheinbridge instead, see here). Why not? Because you don’t need to. It happens all on its own while building on a sphere. Same with the track. It follows the Earth curvature. Just a tiny little bit, it is only 250 m long, 95 m wide, but the curvature is there. It is very small, that is why you have to go around 100,187.5 times. But it is there.
Probably. Rounding errors on this scale are relevant. Imagine the track is badly built, and the middle is 2 cm lower than the ends, for whatever definition of middle and of ends. Then your feet would walk further than your head, not the other way around. But Godott fearing proper American builders would not do such a mistake, would they?
There are some buildings large enough that the curvature is significant. In the vast majority of them, they choose to make floors level, not flat (i.e., they’re a section of an Earth-sized sphere). Level matters for a lot of practical purposes (such as not forming puddles), while flat matters for hardly anything.
So you are using “section” in the meaning as the address of a plot on a map, not as a unit of measurement of area.
By the way, two people shocked me not long ago when they asserted that a section is one mile by one and a half miles! One of them grew up in a city and so it isn’t surprising that he could be so wrong. The other one grew up on a neighboring farm (that is not all that far from Kansas). I think that his confusion is that his family farm is made up of four quartersections in a shape like an L – actually, a backwards L. So, at the big end, the farm is a mile wide while at the small end it is a half mile wide.
One of my neighbors when I was growing up owned something like 100 sections of farm and ranch land. By the time he passed away, years later, he owned more than 200 sections of land in Oklahoma and Texas – my recollection is that it was around 235 sections, but I may be wrong. Nobody would consider that to mean that he owned 235 individual pieces of land that were each one mile by one mile.
Did they prove, definitively, that walking that circle against the spin of the Earth does not cause the walker to go back in time?
A fact I didn’t stumble across but was curious enough to look up: On the Bewitched television series Darren worked for the McMann & Tate advertising company; Howard McMann appeared in exactly two episodes and was portrayed by two different actors.
Were they in the eras of the two different Darrens? Maybe when Samantha magically changed him, she changed every other muggle in the world at the same time.
(and I’m amused to see that “muggle” doesn’t trigger Chrome’s spellcheck).
This is the main difference between the UTM coordinate system (or any “projected” system), and latitude/longitude (the one commonly used “geographic” system).
UTM is “flat,” while lat-long is “level.”
You can see how much they diverge across large distances (something billy-jack brought up, above) by observing how a UTM grid overlays lat-long lines in, say, a USGS topo map…or by seeing how one UTM zone misaligns with the adjacent UTM zone.
It is indeed why you have funny jogs on rural highways in much of the Midwest — section (or township) line adjustments. Some are to correct 19th-century survey errors, but most are a necessary consequence of meshing “flat” and “level” — typically about a fifty-foot jog every forty miles or so (don’t quote me on those numbers, but that feels about right).
Have a look at the Manitoba-Saskatchewan border. From a distance, it appears straight. Zoom in and you will see a slight “jog” at regular intervals. The “jogs” are at 38.62 km intervals. The Alberta-Saskatchewan border is absolutely straight.
But how much farther would your nose run?
Correct. A section contains 640 acres. But 640 acres do not necessarily create a section.
(Hope that makes sense!)
Interesting random fact: put up fast, and spray painted white, at a time when spray painting was fairly new, and white was the standard or only spray color available.
Hence the political expression “a level playing field”. Ironic that a properly leveled playing field isn’t level – it’s graded so that water runs off, instead of pudling.
You may be familiar with Noel Coward’s “Mad Dogs and Englishmen” from 1931. The lyrics deal with what the Brits did in eastern Asian countries on hot days. Part of the lyrics read:
“Mad dogs and Englishmen go out in the midday sun
The smallest Malay rabbit deplores this foolish habit
In Hong Kong they strike a gong and fire off a noonday gun
To reprimand each inmate who’s in late.”
In 1965 - Noel Coward fired the noonday gun in Hong Kong.
They still ring a bell and fire the gun every day at noon - a big tourist attraction.
Stephen Colbert’s family traditionally pronounced their name as it looks ( in normal English rules). He changed it to a French pronunciation on his own.
This seems kind of confusing. If you take off from Sydney NSW and lock your heading to 90º (and you have extra fuel tanks), after nearly a day at 500mph, you will find yourself passing over the south end of the Bahamas. We think of East as following a line of latitude, but the real meaning seems to be something entirely different (except at the equator and the poles).
I guess it depends on what you mean by “lock your heading to 90º”, and I am surprised some aviation and navigation expert has not chimed in yet, but Sydney is in the South hemisphere and the Bahamas in the North hemisphere, I am not sure you and I are visualizing the crossing of the equator with your heading locked 90° the same way.