Heartbeat line tattoo on the back of the neck

The machine in Ward Nine is older than both of us put together, a grey box with a stylus that scratches its line onto paper that unspools like a long ribbon. Mr Akinola on the night desk calls it the old tin fiddle. Last night it drew the line for a man in bed four who had been arguing with the porters about the football, and I stood with the paper running through my fingers and watched every peak rise and fall, one after another, as neat as stitching. I'm telling you because you asked in your last letter what I actually do all night, and this is the nearest I can get to an answer.

Nobody tells you that a heart draws a shape. The sharp spike is the squeeze, the small hump after it is the rest, and the flat stretch between is where the whole thing waits to be asked again. When the line runs flat for too long, the pen goes quiet and someone comes running. I have never once run. I walk, and I keep my hand steady, and I read the trace the way Dad used to read the weather off the harbour wall.

Last Tuesday I tore off a strip for the consultant and folded it into my apron pocket by mistake. I found it at home, creased into a small zigzag, and I couldn't bring myself to throw it away. It's pinned above the kettle now. Every morning I look at it while the water heats, and I think that a line can be the most ordinary thing in the world and still be the only proof anybody needs that they're here.

Write soon, and tell Mum I'm eating properly.

Love, Jo