From coconuts to GPS: A brief history of navigation

It's good, but it's no coconut. Image: Getty.

If I ask Google:

It helpfully displays a map of where I used to live:

Google is very good at knowing where I used to be. My phone is constantly keeping track of my location and uploading it to their servers. It has stored my location 579,088 times since September 2013.

Each location stored looks like this:

{
 “timestampMs” : “1431497952458”,
 “latitudeE7” : 513453840,
 “longitudeE7” : -1015043,
 “accuracy” : 27,
}

This isn’t that easy to read. The E7 is an instruction to divide by 10,000,000, to reach a traditional set of latitude and longitude coordinates. “timestampMs” tells us that wherever 51.345384° N -0.1015043° E is, I was there at 1,4314,9795,2458 milliseconds after midnight on the 1st January 1970.

Even knowing what each of those numbers represent, we need to do some work to get these back into a human context. By putting the numbers through mapping software I can find out that “51.345384°, -0.1015043°” is Purley Oaks station in South Croydon. By running the timestamp through a conversion system, I can see I was apparently there at 7:19:12 AM on the 13 May 2015. This makes perfect sense, it was part of my daily commute at the time — I’d have been there most days at that time.

Most of the data stored about my location places me somewhere I lived or somewhere I worked. Just occasionally, I do something interesting and the database gets to store whole new sets of coordinates. If I take several years of this data I can produce maps of the sums of my positions over time:

This is my life as latitude and longitude, expressed in a way that can be easily understood by a human. Where I’ve spent any amount of time the map is redder; journeys appear as snail trails across the country.

Google’s algorithms don’t require any of this “coloured in map” nonsense. After a few weeks, your Android phone can make a reasonable guess at where your work and home are, based on where you spend most of your days and where you spend most of your nights. It doesn’t need to ask — that would be intrusive.

To determine a position on a globe while inconveniently being stuck on that globe you need fixed external references. Fortunately the universe is full of these.

One of simpler means sailors used to work out their relative position from destination was a kamal – a board with a hole in the middle. By putting a string through the hole and holding one end of the string in your teeth, you position the lower edge of the board on the horizon and move it further away until the board obscures your target star (typically Polaris — if visible).

An enthusiastic Wikipedia editor showing how the kamal works. Image: Markus Nielbock/Wikimedia Commons.

The length of the string between your teeth and the board tells you your latitude. By knowing the length of string required for certain ports, you could adjust course to navigate to a place. Using nothing more than your teeth, a string, a plank of wood, a star – and the horizon.

In Polynesia (lacking in a helpful pole star) titiro ‘ētū – “star peekers” – made of nothing but coconuts and seawater were used to navigate to specific islands. To use these, you cut off the top of the coconut and make a ring of holes around the base. You then make a hole near the top for the target star and fill it with water up to the holes (with coconut oil to maintain surface tension). You look through the device at the star at its highest point; if the water inside the device is flat, you are on the same latitude as your destination. The stars will guide you with the simplest of tools, if you know how to use them.


Progression east-west (longitude) can be understood if you know the difference between high-noon on a clock set at a fixed location (Greenwich) and a clock set at the current location. Each hour difference represents 15° of travel longitudinally (1/24 of 360°). Simple enough, if you have a clock that can keep time on the ocean – but that was a complicated problem to solve. Before that, all sailors could really do is line up on the right latitude and go for it.

To make use of more markers than the sun and North Star, you could use nautical almanacs and sextants. These almanacs were essentially large lists of what celestial objects should appear at certain points of the sky, and at what time they can be expected to do so. By using the sextant to compare predicted appearances to actual locations, you can determine the distance to fixed positions.

The Global Positioning System (GPS) has mostly replaced the need for these tables. Reliable but not available on-demand stars have been replaced by artificial celestial bodies that spend their whole lives yelling about where they are and what time they think it is. By comparing signals from several different satellites to the time your GPS device thinks it is, you can triangulate your position on the earth within a few meters.

Few mobile phones contain true GPS: mostly they use aGPS or WPS. aGPS uses the resources of the mobile network to speed up reconciliation based on fragmented signals, but WPS (Wireless Positioning System) is something different altogether. It takes advantage of the fact that we littered our world (especially urban areas, where GPS struggles) with millions of radio location beacons, in the form of Wi-Fi access points.

While the vans with the weird cameras were taking pictures of every road in the world, they were also mapping the radio landscape we have made: each house with a Wi-Fi access point, broadcasting a unique identifier. By mapping these to a true GPS reading, location services can provide a guide to any device with a wifi chip. If you read Device #1053443 with 50 per cent strength and Device #10232321 with 74 per cent strength and Device #24324239 with 60 per cent strength, the chances are you are “here” — the most likely place where those signals converge at that strength.

These vans are no longer necessary: while walking around your phone will pick up on any new or unknown access points. With sufficient logs of these devices, their location can be deduced by comparison to known devices and used for future navigation. As well as recording our every step, our phones are automated radio cartographers. This is still ultimately working on similar principles to the nautical almanac and sextant, it just has a much larger look-up table and uses thousands of man-made stars to light the way.

As navigation has become much easier there is also the risk of becoming too dependent on what might turn out to be fragile technology. The US Navy is currently re-introducing celestial navigation training. so that its sailors can figure out where they are in the event of an attack on the GPS system. After the apocalypse, we might find ourselves getting around by holding a bricked phone up to the horizon and measuring the length of the headphone cord to our teeth. 

 
 
 
 

Cycling on London’s Euston Road is still a terrifying experience

Cyclists on the Euston Road. Image: Jonn Elledge.

The New Road, which skirted the northern boundaries of London’s built up area, first opened in the 1750s. Originally, it was intended to link up outlying villages and provide a route to drive sheep and cows to the meat market at Smithfield without having to pass through the congested city centre. 

As with bypasses and ring roads the world over, however, it increasingly became congested in its own right. Today, you won’t often find livestock on the route, which is now Marylebone, Euston and City roads. But you will find up to six lanes of often stationary buses, cabs, and private vehicles. In a city whose centre is largely free of multi-lane highways, London’s northern ring road has long been the sort of abomination that you avoid at all costs.

But now, somewhat surprisingly, the road is seeing yet another new use. Earlier this week, the first phase of a temporary cycle lane opened on the Euston Road, the middle section of the route which runs for roughly a mile. As London rethinks roads throughout the city, this addition to the cycling map falls solidly into the category of streets that didn't seem like candidates for cycling before the pandemic.

It is, to be clear, temporary. That’s true of many of the Covid-led interventions that Transport for London is currently making, though those in the know will often quietly admit to hoping they end up being permanent. In this case, however, the agency genuinely seems to mean it: TfL emphasized in its press release that the road space is already being allocated for construction starting late next year and that "TfL will work with local boroughs to develop alternate routes along side streets" when the cycle lane is removed.

At lunchtime on Friday, I decided to try the lane for myself to understand what an unlikely, temporary cycle lane can accomplish. In this case it's clear that the presence of a lane only accomplishes so much. A few key things will still leave riders wanting:

It’s one way only. To be specific, eastbound. I found this out the hard way, after attempting to cycle the Euston Road westbound, under the naive impression that there was now a lane for me in which to do this. Neither I nor the traffic I unexpectedly found myself sharing space with enjoyed the experience. To be fair, London’s cycling commissioner Will Norman had shared this information on Twitter, but cyclists might find themselves inadvertently mixing with multiple lanes of much, much bigger vehicles.

It radically changes in width. At times the westbound route, which is separated from the motor traffic by upright posts, is perhaps a metre and a half wide. At others, such as immediately outside Euston station, it’s shared with buses and is suddenly four or five times that. This is slightly vexing.

It’s extremely short. The publicity for the new lane said it would connect up with other cycle routes on Hampstead Road and Judd Street (where Cycleway 6, the main north-south crosstown route, meets Euston Road). That’s a distance of roughly 925m. It actually runs from Gower Street to Ossulton Street, a distance of barely 670m. Not only does the reduced length mean it doesn’t quite connect to the rest of the network, it also means that the segregated space suddenly stops:

The junction between Euston Road and Ousslston Street, where the segregated lane suddenly, unexpectedly stops. Image: Jonn Elledge.

 

It’s for these reasons, perhaps, that the new lane is not yet seeing many users. Each time I cycled the length of it I saw only a handful of other cyclists (although that did include a man cycling with a child on a seat behind him – not something one would have expected on the Euston Road of the past).


Though I hesitate to mention this because it feeds into the car lobby’s agenda, it was also striking that the westbound traffic – the side of the road which had lost a lane to bikes – was significantly more congested than the eastbound. If the lane is extended, it could, counterintuitively, help, by removing the unexpected pinch points at which three lanes of cars suddenly have to squeeze into two.

There’s a distinctly unfinished air to the project – though, to be fair, it’s early days. The eastbound lane needs to be created from scratch; the westbound extended. At that point, it would hopefully be something TfL would be keen enough to talk about that cyclists start using it in greater numbers – and drivers get the message they should avoid the Euston Road.

The obvious explanation for why TfL is going to all this trouble is that TfL is in charge of the Euston Road, and so can do what it likes there. Building cycle lanes on side nearby roads means working with the boroughs, and that’s inevitably more difficult and time consuming.

But if the long-term plan is to push cyclists via side roads anyway, it’s questionable whether all this disruption is worth it. A segregated cycle lane that stops without warning and leaves you fighting for space with three lanes of buses, lorries, and cabs is a cycle lane that’s of no use at all.

Jonn Elledge was founding editor of CityMetric. He is on Twitter as @jonnelledge and on Facebook as JonnElledgeWrites.