James May on: instruction manuals

The directions on the can said: "Dispense a walnut-sized blob of foam into the palm of the hand." Well, I thought, this was ridiculous.

If they wanted to quantify the amount of foam needed for a shave, then surely they could come up with something a bit more comprehensive than ‘walnut-sized'. The humble walnut, after all, is not subject to British Standards or the Système International d'Unités. Walnut sizes are variable.

But when I thought about it for a bit, I realised I couldn't come up with anything better. A churchwarden's pipe-bowl-sized blob? A blob a bit bigger than a biggie coloured marble? A blob the size of that pointy bit on your elbow, but maybe slightly more? Perhaps the walnut was, in fact, an excellent volumetric datum.

However, it still didn't seem right. I have quite a large head, and all of the bit below my nose and round to the sides, plus the region under my chin, has to be shaved. I haven't worked it out properly, but I reckon around 20 per cent of my bonce by surface area needs to be foamed up. A satsuma seemed more like it.

So I dispensed a satsuma-sized blob into my palm, but that isn't the end of it, is it? It grows.I didn't know this, because I normally use a stick-type shaving soap. It just wouldn't go away, and I ended up scooping it into the bog and attempting to flush it away. That made it grow more.

This is really an elaborate preamble to my question for the month, which is: should we read the instructions? There's a school of thought that says we shouldn't, because it's unmanly. But, hang on: I bet the astronauts read the manuals for the Saturn V and the Lunar Module very extensively, and you wouldn't call them soft.

I think the cult of not reading instructions stems from the narrow technological experience most people have. Most of us only have to deal with electronic devices. Satnav, say.

There's a school of thought that says we shouldn't read instructions because it's unmanly. But I bet the astronauts read the manual for the Saturn V

I've never read the instructions for a satnav. Electronic devices are grindingly logical in the way that only binary things can be. A simple language for programming anything like this, including the apparently baffling alarm radio in a hotel room, has developed over several decades. You press a button, press two buttons together, or press a button and hold it. There aren't that many permutations, and you can work it out easily. Unless you're Clarkson.

And anyway, if you do muck it up, the worst that can happen is that you end up somewhere dreadful, like the Cotswolds. Annoying, but not life-threatening. It's tempting to conclude that instructions suck, big time.

But a word of caution is in order here. This general contempt for users' guides, instilled by cloying familiarity with digital trinketry, should not be allowed into the rest of our lives.

For example, last week I took delivery of a screw-cutting metal-working lathe. Machine tools, it transpires, are utterly unforgiving, and a lathe offers the opportunity to bring steels of varying hardness together at high speed and with mechanical bloody-mindedness, which is catastrophic, especially if the thing has gathered up your clothing or a limb on the way.

Plus - and you can call me dull-witted if you like - I don't have an instinct for which set of gears in the head will make all the bits rotate in the right ratio to cut, say, an M6 screw. There's a chart for this sort of thing, and I'm happy to admit that I've consulted it. Instructions are good, after all.

And there's more. Earlier this year, I took delivery of a Triumph motorcycle. Now I already know how to ride a motorcycle, and the various settings available on the dash display and trip computer I managed to work out after five minutes of fiddling around in the garage. So I never read the guide.

But then, this morning, during a tidy-up, something made me look into it. I had absolutely no idea that I wasn't supposed to carry animals on the motorcycle, or drink the coolant.

Worst of all, I read, with the chill of pure terror in my heart, that attempting to adjust the brakes while the motorcycle is in motion could lead to loss of control and an accident. Thank God I took the trouble to find that out. I could have been killed.

Always read the manual.