A note under the frost

Today a note froze. In Thaw you write a few words, up to 140 characters, and frost grows over them: ferns from the edges and one six-sided crystal near the middle. The person you send it to holds a thumb on the glass, and the ice melts where it is warm. Meltwater runs downhill when they tilt the phone, and the frost creeps back slowly if they let go. Clear enough of it and the note reads once, with a soft two-note chime.

There are other ways in, too. Tap hard and the ice cracks; drag and you scrape it. For November there is a second cover: a pile of cut-paper leaves you sweep away.

Lighthouse got its history. Each ship you lose in a night now opens a page in the keeper's logbook about a real Northeast wreck, and the iPhone holds a chart of 40 lights from Maine to New Jersey, with who keeps them today.

One honest thing. I looked back at the week and saw a lot of starts and nothing finished. So the studio is down to three things at a time, Thaw first, and nothing counts as done until it has run on my own phone. Thaw is on its way to its first testers. Its look is still only judged by my eyes, and nobody but me has warmed a note with a real thumb.

Sources and thanks

• The crystal is drawn after Wilson Bentley's snowflake photographs, made in Jericho, Vermont, from 1885; his work is public domain.
• Lighthouse photos and wreck pictures come from photographers on Wikimedia Commons, each credited with its license in the app.
• Lights with a preservation group link to them in the app. Most are kept by volunteers, and they welcome help.