TIDE TABLE FOR A ROOM

21 September 2026 · 51.500 N, 0.120 W · solar noon 12:53:30, the sun 39.09° up

The room is 4.2 m east to west, 3.6 m north to south, 2.55 m high, with one window in the south wall running from 1.05 m to 2.85 m along it and from 0.9 m to 2.05 m above the floor, set back 0.34 m in the thickness of the wall. There is nothing else in the way. Given that room, on that date, at that latitude, every time below is correct to the second.

Direct sunlight, first touch to last
First	Last	Total	On
—	—	never	the near edge of the floorboards
11:33:52	15:04:16	210m 25s	a glass of water on the low table
10:22:00	13:09:48	167m 49s	the arm of the chair
15:14:15	17:06:47	112m 33s	the spine of the third book down
—	—	never	the brass handle of the door
12:30:58	14:59:37	148m 40s	the left eye of the cat, asleep
08:19:22	11:58:07	218m 46s	a fold in the curtain
—	—	never	the dust on the picture glass
11:55:36	15:31:21	215m 46s	the rim of a cup left since morning
11:48:55	14:18:22	149m 28s	the seam of the rug
17:05:30	17:37:11	31m 42s	the light switch
08:47:07	10:03:22	76m 16s	the top of the radiator
—	—	never	a nail, painted over, in the north wall
—	—	never	the ceiling, directly above the sill

Five of the fourteen are never reached at all. The floor directly beneath the window is one of them: to clear its own sill it would need the sun 68° above the horizon, and on this date, here, it never gets past 39.09°.

This table was computed, not observed. If you are in a room with a window, the times will be wrong for you, and finding out how wrong is the only part of this that happens outside a screen.