It was a warm weekend in London. Yesterday, Jay and I went to Hampstead Heath to swim in one of the park's ponds. It was a lot of fun. The ponds include a men's pond, a women's pond and a mixed-sex pond (there are other ponds where no swimming is allowed). We went to the mixed pond.

The pond is bordered by a thin, grassy "beach" crowded with people. There are also an outdoor changing area and rest rooms. To go swimming, you walk out on a concrete pier and either jump in or lower yourself into the water via a ladder.

The water is COLD. But you do get used to it after a bit. I went swimming once. Jay went three times and swam as far out as he could before coming back.

The oddest thing about swimming in the pond is that your feet never touch bottom. It's nothing like swimming in a pool or at a beach. Poles and life-preserver rings are scattered around the pond for people needing a rest.

I have to say I was a lot cooler after my swim. And it was nice to stand in the sun and warm up.

If you walk around London long enough, you will see people on motor scooters equipped with clipboards. Who are these people?

They are aspiring London cabbies, learning the tangled network of roads they will have to negotiate in a city that dates back to the Roman Empire. This is a place where street names change unpredictably; just down the block from where I work Clerkenwell Road becomes Theobald's Road. And the grid street plan is an alien concept.

Taking a book of street maps along when you venture outside your neighborhood is considered normal. The standard work is the "A to Z", also referred to as the "A to Zed" (We have two of them).

The process of learning London's streets in order to qualify as a cabbie is called "getting the knowledge."