50 Years Ago

I wish to appeal to my fellow geologists and workers in the rapidly growing subject of geochronology to discontinue a habit or fashion which is both unnecessary and misleading. I refer to the habit of calling radiometric ages 'absolute' ages. An age does not become 'absolute' by virtue of being expressed in units of time such as a year ... The term is not only redundant and both philosophically and scientifically without meaning: it is also misleading in its psychological suggestion of a higher degree of accuracy than can be justified ... If any of the culprits claim that they are in good company with Newton and Kelvin, who both wrote of 'absolute time', they have only to remember Einstein and the coming of relativity.

From Nature 22 December 1962

100 Years Ago

'Smoke trace of compound vibrations of tuning-fork' — The accompanying print is from one corner of a smoke trace used by me at a popular lecture in 1901. One curve shows the fundamental (128 per second), another the first upper partial, while the centre curve of the three shows the form of vibration executed when the first upper partial is sounding, together with the prime. The three sounds may be heard by the audience, and the smoke traces of each obtained in their presence.

From Nature 19 December 1912