100 YEARS AGO

Certain letters have appeared in Nature upon the bearing of the properties of radium upon the cosmical time scale. These letters are based on the assumption that radium, or some equally active body, exists in the sun and contributes materially to the output of solar energy. If this assumption were true, we ought, I think, to be able to detect the rays peculiar to radio-active bodies on the surface of the earth — they should bear some proportion to the great stream of light and heat waves which reaches us. Now a solution of iodoform in chloroform is very sensitive to the β and γ rays. A purple coloration is produced by the rays from 5mg. of radium bromide even after filtering through 1cm. of lead. On the other hand, I find that direct sunlight (if heating be obviated) has no action when the thinnest screen is interposed even after many days. Some of my solutions are now nearly two months old, and they have been exposed in light-tight cardboard boxes to such sunshine as has reached us during that period. They are quite unchanged. It is, of course, possible that the stream of rays needs to be above a certain critical density in order to decompose the iodoform, but in any case, my experiments prove that the β and γ rays reach us at most in only faint quantities from the sun.

From Nature 8 October 1903.

50 YEARS AGO

During a short survey of Milford Haven (July 27–30, 1953) for the purpose of assessing the possibility of reviving the oyster fishery, six American slipper limpets (Crepidula fornicata) were found in or near Pennar Gut, the estuary of the Pembroke River. Crepidula, a serious pest of oysters, had previously been recorded only from the east and south coasts of Britain... Pennar Gut was used in the years following the Second World War for laying up both merchant and naval ships, and is adjacent to Pembroke Dock. There is a ship-breaking yard on the opposite shore near Milford Haven. Evidence has been adduced to show that a major factor in the spread of Crepidula has been the movement of laid-up naval and merchant ships, which may remain for several years in infested areas on the east and south coasts of Britain and later be transferred for refitting or breaking-up to other areas.

From Nature 10 October 1953.