100 YEARS AGO

Referring to Mr. Hardy's experiment described in his letter in Nature, October 8, it is easy to show that whatever the intensity of radio-activity might be at the surface of the sun, by mere surface ratios and assuming no absorption its activity per unit area at the distance of the earth must fall to about one forty-thousandth part... This supposes no absorption from, possibly, some thousands of miles of solar atmosphere. Moreover, we assume in the comparison a sun of solid radium bromide. It would appear, however, that a very small percentage of this body in the materials of the sun would suffice to account for many millions of years of solar heat. ... The absence of β and γ radiations at the earth's surface is, therefore, not a weighty argument against the presence of radium in the sun. The arguments in favour of supposing that this element exists in the sun are:— (1) The presence of radium on the earth; (2) the high atomic weight of radium; (3) the presence of helium in the sun; (4) Arrhenius's theory of the Aurora Borealis; (5) the fact that the estimate of the duration of solar heat from the dynamical source appears to run counter to geological data.

J. Joly

From Nature 15 October 1903.

50 YEARS AGO

Forthcoming events

Monday, October 19

Institution of Electrical Engineers (at Savoy Place, London, W.C.2), at 5.30 p.m. — Discussion on “Television”.

Tuesday, October 20

University College, London (in the Anatomy Theatre, Gower Street, London, W.C.1), at 1.15 p.m. — Prof. J. B. S. Haldane, F.R.S. : “The Physiology of Diving”.

Institute of Physics, Education Group (at the Royal Institution, Albemarle Street, London, W.1), at 6.30 p.m. — Prof. O. R. Frisch, F.R.S. : “Atomic Energy — How it all Began”.

Wednesday, October 21

Geological Society of London (at Burlington House, Piccadilly, London, W.1), at 5 p.m. — Prof. J. Z. Young, F.R.S. : “The Evolution of Vertebrate Organization”.

Thursday, October 22

University College, London (in the Anatomy Theatre, Gower Street, London, W.C.1), at 1.15 p.m. — Dr. Randolph Quirk : “Careless Talk : Some Features of Everyday Speech”.

From Nature 17 October 1953.