An unusual wedding proposal

I don’t often tell this story now, but it’s still a good one and one worth sharing. It combines my geekiness with some romance. For some more details of how this was made, see the making of the box.

Geocaching

Geocaching (roughly expanded as Location-Store) is a hobby where you hide something ‘fun’ in a public place, mark it’s location using GPS, and then others use try to find it using it’s GPS co-ordinates and a clue. Once found, you can take the item and replace it with something of your own. We’ve only ever tried this once, it was kind of fun, but not so great that we did it again.

Reverse Geocaching

So what if you could do this the other way around? Rather than hide an item, and provide a location to find it; you gave the other person the item in a locked box, and they had to find the location where it unlocked. This was the brain child of Mikal Hart, who created both the main circuit board and code that made this story possible.

The Story

I gave Sarah a locked wooden box for her Birthday, which was once a Victorian tea caddy. It had no markings, keyhole or lock, just a small screen and a single silver button. Accompanying it was a short poem:

My gift to you an ancient chest,
Full of mystery and surprise;

You must travel near and far,
To find where treasure lies;

It’s owner must think carefully though,
As rushing be not wise.

Naturally curious, Sarah pushed the button and the screen read; “Hi Sarah, Your Present Awaits You… Seeking Signal” before returning the next part of the message; “Attempt 1 of 30, Distance 316.8km, Access Denied.”

It took a while before she realised that the box knew where it was. It had a GPS tracker inside and Sarah could only assume that it would open when she was in the right place – when the distance would read zero. But how to find a location that was over 300km away in only 30 presses?

Around a fortnight later, after a couple more pushes of the button, her sister’s boyfriend realised that if you drew a circle around you on a map, the right location must lie on that circle. A few more days passed, and I asked ‘what if you drew two circles, from two different places?’ With three circles there is only one intersection and you’ve found the location. Well to the nearest few miles at least, but the box would need to be within 40m of the programmed location.

Locations of button pushes mapped with circles added

The box was duly sent with her sister on their holiday near Gloucester. That added another circle and after a few puzzled days with circles missing most of the UK mainland, she realised it was set on Bruges in Belgium; the location of a previous holiday. Nearly two months after receiving the box, tickets were booked - by ferry – the airport conversation being rather predictable:

Presses and final opening location in Bruges

Security Man: “Did you pack that yourself?”
Sarah: “No”
Security Man: “What’s in it?”
Sarah: “I don’t know”
Security Man: “Can you open it for me please?”
Sarah: “No, it won’t open here.”

A few more presses around the city and she drew some more circles on a tourist map (we’d taken a compass with us!) and there was some inkling of roughly where it might open. I suggested we take a horse and carriage ride to get another reading further away (Sarah has a love for horses so it didn’t take much persuasion). Another press and the display counted down “620m, 602m, 578m” as the carriage trembled over the cobbled streets.

Arriving at a watering hole by the Lake of Love, where legend says couples throwing a coin in to the lake will have eternal happiness, the box displayed “Access Granted” and made a gently whirring noise as the lock inside retracted. Sarah lifted the lid and was greeted by the engagement ring that she had unknowingly been carrying around for over 2 months.

We completed the day with a carriage ride back to the main square and a hot air balloon ride over the city. Sarah knew I had something planned, but she still suspected it was the tickets for the evening that would be in the box.