LONDON’S Millennium Bridge is not the only structure in the world with a
tendency to wobble (Â鶹´«Ã½, 31 March, p 38). Reader Chris Knibbs
encountered the same problem when he built a perch for his chickens.
He wanted it to be “realistic”, like a tree branch, so he suspended a short
pole on wires that could sway slightly. Unfortunately, even a minor swing would
set the birds leaning forwards and back in unison to counter the sway of the
perch. This made the perch sway more. So the chickens rocked further and
faster.
“I would be woken by the sound of loud creaking noises…
