The useful habit is to ask what each feature is for rather than what it looks like. Nearly every one addresses a specific difficulty, and several address problems that are…
The distinction that organises the whole subject is between comparing and measuring. A balance compares; a scale measures a force. Almost every difference between weighing devices follows from which one…
The useful way to read any station is to work out which of two plans it is, then look at how the roof is held up. Those two facts explain…
The useful habit is to read a map as an argument rather than as a photograph. Somebody decided all of this, and knowing what they decided tells you what the…
The whole subject is fluid control. Too little and nothing appears; too much and it blots; and the difference between the two is a matter of fractions of a drop.…
A built viewpoint is an argument about what matters in a landscape. Somebody chose the position, the height and the direction, and everybody who stands there afterwards sees what they…