Miss Prim's such a comfort

SATNAV - PART ONE Has satnav done the job? Artics are still getting stuck in green lanes in Devon. Even enthusiasts (like me) admit that intelligent awareness is better than blind faith when Miss Prim says: "At the roundabout, take the second exit".

But consider the skills required to create even an imperfect system that maps the backlanes of Britain and France and receives guidance from man-made planets. All contained in a cough-drop box and retailing for about £250. Surely that's worth a tip of the hat.

Forget direction-finding for a moment. Switch to ETA mode so that the device calculates - and updates - the time left before you arrive at your chosen destination. Strangely comforting to see the minutes tick off, even on motorways.

The picture shows a satnav holder made by my DIY perfectionist brother, presently doing Land's End to John O'Groats on foot. Without electronic aids.

TECHNO-ART Technology in literature? Well, let's start with fiction. Neville Shute helped design the R101 airship before turning his hand to best-selling novels in the fifties. Best-known probably for "A town like Alice" and the apocalyptic post-nuclear "On the beach". In others nuts-and-bolts were the heroes - as for instance, "Trustee from the toolroom", which suggests - unfairly - that titles weren't his thing.

The unforsaken merman

Already I'm cheating on my stated aims. Can swimming crawl possibly snuggle under the umbrella of technology? Belatedly I open the dictionary. The first two definitions are predictable, the third offers a Damascene moment: "The totality of the means and knowledge used to provide objects necessary for human sustenance and comfort." That word objects - surely it has an intangible well as a tangible meaning: goals as well as things? For me crawl works, it's the most effective form of aquatic self-locomotion. The hard bit is learning the breathing. After that it's pure sensuousness. I experimented with my kick this morning: kicked hard and felt the resistance to my arm stroke diminish in the water. Joy.

Here’s how you hoist up the John B sail

This lovely thing is a Meissner Classic winch and is intended for hoisting and releasing a yacht's sails. It withstands enormous forces as becomes apparent if you incautiously unhook the rope from that beautifully shaped securing device and leave your fingers in the way. Engage a crank in the top and the mechanical advantage allows a human to haul with the power of ten. A ratchet prevents the wind-filled sail from biting back. That's all there is, really. Yet those on my brother's yacht cost £700 each. A matching pair would look good on your mantelshelf (as they say in the North).

Car door needs protecting from physics

Remember the law of levers. The longer the lever the greater the force that can be applied. My car door is just one example of why you should always stay on the right side of this particular law. When open, the door's edge extends some 1.5 m away from the car body. Far enough for the weight of the door itself (no lightweight) to deliver plenty of destructive force at the attachment point to the car. The idea of a driver leaning on the top of it while chatting to someone in the car park doesn't bear thinking about. Which is why the hinge (one of two) in the centre of the photo is extremely substantial. I'd be overdoing things if I called the hinge pretty but it has its own rugged charm. Rugged and reassuring. I glance at it with pleasure every time I get into the car.

TECHNO-ART Which painter made best use of technology as a subject in an acknowledged masterpiece? Answer: Turner in "Rain Steam and Speed". Closely followed by his poignant canvas of The Fighting Temeraire being towed to the breaker's yard by a steam tug.