The number your weather app calls "feels like" has never described you.

For most of a century it described a bottle. In 1940 Paul Siple and Charles Passel hung a small plastic cylinder of water from the roof of an Antarctic hut, level with the anemometer, and timed how long it took to freeze. What they published in 1945 was a cooling rate in kilocalories per square metre per hour — a four-digit number, not a temperature. Somebody else converted it into the friendly negative one a radio announcer could read.

That held until 2001, when a joint American, Canadian and British group replaced it. The current index models heat leaving a bare adult face turned into the wind, walking into it at 3.1 miles an hour. The wind comes off the standard anemometer at thirty-three feet and is scaled down to five feet, where a face is. The sky is clear and it is night, so the sun contributes nothing. Twelve volunteers, six men and six women, spent ninety minutes at a stretch on a treadmill in a chilled wind tunnel in Toronto with thermal transducers taped to their foreheads, cheeks, noses and chins.

The numbers came down hard. St. Louis reported 69 below on 20 January 1985; run that day through the current formula and it is 48 below.

None of which made the number about you. You have a hood up, you are standing still at a light, it is two in the afternoon and the sun is out. The old index at least sounded like an instrument. This one sounds like a person, and there is a particular one it means: bare-faced in the dark, walking into the wind at exactly 3.1 miles an hour.

The box an expensive object came in is rarely allowed to become trash at the same speed as the object becomes ours.

A phone, watch, or pair of headphones leaves its box in seconds. The box then waits for years. It occupies the back of a closet with its precise recesses empty, too finely made to hold anything else and apparently too important to discard.

Packaging is supposed to be temporary architecture. This kind is too competent at its job: dense board, exact tolerances, a lid descending on a trapped cushion of air. Throwing it away feels less like clearing debris than discarding part of the purchase.

We say we keep it for resale, moving, or the warranty. Sometimes that is true. Mostly, I think the box guards a more flattering possibility — that our choices remain reversible. The object may be scratched and absorbed into daily life, but its box preserves the day we chose it as a clean decision we could still undo.

I like the moment the box finally goes. It is not decluttering. It is an accession ceremony. We stop treating the thing as merchandise and admit it has joined the household. The return window closed years ago. Ownership happens on recycling day.

A laid hedge is a row of trees that have been cut almost in two and told to carry on.

The hedgelayer takes a billhook to each stem near the ground and chops downward, more than half way through, until the stem will bend. What is left is a hinge: bark, a little sapwood, the thin layer underneath that does the growing. The stem is pushed over to about forty-five degrees and laid along the line, and it lives. Sap crosses the hinge as it did before. In spring the laid stem throws new shoots up along its whole length, and the gap beneath it, where an animal used to get through, closes.

Cut too shallow and it will not bend. Cut too deep and you have firewood. The craft is the width of that tongue.

Hedgelayers lay uphill. Sap rises, they say, so the trees keep climbing through the wound. And they lay in a dialect. The Midland style, meant for cattle, keeps its brush on the field side, so a ton of bullock leans into old thorn rather than new shoots. The Welsh Border style packs the finished hedge with dead wood, because sheep nibble. Devon puts the whole thing on top of a bank. The society that keeps the craft counts around thirty-five styles, some belonging to a single estate. You can read the animal off the fence.

Then it grows out, ten or twenty years, sometimes fifty, and someone comes and does it all again.

I keep coming back to the arithmetic. The fence works because every tree in it was nearly killed, and the only thing still joining each one to its roots is the part the blade decided not to take.