There are two good reasons for a trip to Sir John Soane's Museum at present - not that an excuse is needed. One is the splendid exhibition of Robert Adam drawings. The other is an installation in the Breakfast Room by artist David Ward, currently teaching at Westminster University and the AA. Called 'Weight & Measure', it takes its cue from drawings made by Soane's students when they were studying Stonehenge. Two plumb lines, one with a lead bob, the other glass, are suspended above partly-overlapping glass discs, one mirrored, the other plain - and all under Soane's amber light, in that room of many mirrors.
Unobtrusive, but mysterious and hypnotic, it's only on show until 26 July - try to see it.