July 11, page 29: The infographic about U.S. coin composition incorrectly stated that the penny acquired its current composition in 1984. It actually changed in 1982. Also, coins are struck from planchets (not cast from molten metal) and some (not all) dollar coins produced between 1849 and 1889 contained 90% gold.
Sarah Everts’s Newscripts column on cats and gravity (C&EN, July 18, page 40) calls to mind an experiment that Alexander Graham Bell and friends performed many years ago and that was reported in a CBC Radio broadcast in the 1940s.
Bell was entertaining two American friends, one an engineer and the other a mathematician, at his home in Baddeck, Nova Scotia. They were discussing the supposed ability of cats to always land on their feet. The engineer was sure that they could, but the mathematician maintained that it was impossible. Bell proposed a trial.
He called for his gardener/handyman and asked him to collect as many cats as he could. Bell then gathered up all the cushions from the living room furniture and laid them on the patio. When the gardener/handyman returned with a basket full of puzzled cats, everyone but Bell took them up to a balcony from which the cats were dropped, one by one, with all sorts of initial attitudes, onto the cushions below, as Bell watched. He was able to report that all landed on their feet.
The mathematician conceded that he had erred in considering the cats to be rigid bodies, which they manifestly are not.
Robert A. Stairs