XXX 



Contents 



No. 14. THE SOLAR ECLIPSE OF APRIL 17, 1912. (From Nature, 



May 9, 1912, Vol. LXXXIX, p. 241.) 44 



This remarkable eclipse had a peculiar interest of its own, 

 and the observers of it had the advantage that the central 

 line passed through Paris and many other important places 

 in Northern Europe, but up to the last moment it was un- 

 certain whether the eclipse would be total, annular or partial. 

 The value accepted for the apparent diameter of the moon 

 was therefore of paramount importance. I observed it in 

 front of the school house at Eaubonne, a northern suburb of 

 Paris, and used an ordinary binocular when the naked eye 

 was not enough, and a hand-screen made of three coloured 

 glasses which reduced the density of the sun's light without 

 altering its colour. This was a very efficient instrument and 

 I am sorry that I do not know the source from which it 

 was obtained. I bought it from a hawker in the streets of 

 Barcelona, on the eve of the eclipse of August 30, 1905, and 

 of course, like all hawker's goods, it was anonymous . . 405 



I used it in front of the eye-pieces of the binocular and 

 with it the diminution of the luminous crescent could be 

 easily followed, and the view furnished was very sharp. As 

 the area of the luminous crescent diminished rapidly before 

 the advance of the dark lunar disc the colour of its light 

 suddenly changed to a deep red. It would have been im- 

 possible to perceive the red colour, intense though it was, 

 had it not been for the perfection of the hawker's reducing 

 glass 407 



After the light of the solar crescent had become red the 

 lower cusp became indented by black blades or teeth ; then 

 the upper cusp showed a similar phenomenon and almost in 

 a moment the teeth spread irregularly over the whole cres- 

 cent, crossing and intersecting each other like a crystallisation. 

 Very quickly the dark disc of the moon advanced and pushed 

 the beautiful network over the eastern edge of the sun, and 

 apparently at the same moment the network reappeared, 

 coming over the western edge of the sun, attached to the 

 black limb of the moon and at the same time held by the 

 limb of the sun. In a few moments the uncovered crescent 

 of the sun had increased so much that the delicate lacework 

 could no longer bear the tension, it parted and disappeared 

 instantly, while at the same moment the dark limb of the 

 moon recovered its perfect smoothness of outline. This was 

 the form which "Baily's beads 1 ' took in this memorable 

 eclipse. The pattern observed by Baily himself in 1835 was 



