50 Years Ago

'Internal circulations within liquid drops' — It has long been recognized that under certain conditions some sort of axisymmetric flow is induced within liquid drops as they pass through a viscous medium ... Although an internal circulation theory has been very attractive in considerations of meteorological phenomena, there appears to be little experimental evidence to substantiate such a theory ... In this communication we discuss a technique which affords velocity measurements and at the same time outlines the vortical core ... The streamlines within the drop are recorded photographically by means of dye trails. The figure indicates the streak-lines due to the motion within water drops moving through mineral oil ... We have obtained a great deal of velocity data with this method.

From Nature 27 April 1963

100 Years Ago

The twinkling of stars may be imitated in the dark-room. If a small light be looked at in a dark-room, as, for instance, that coming through the smallest diaphragm of my colour perception lantern, ... care being taken not to move the eye, the light will appear to twinkle like a star. It will be noticed that pale bluish-violet circles start at the periphery of the field of vision, and, gradually contracting, reach the centre. On reaching the centre the light brightens. If the circles stop the light disappears. The colour of the circle is the same for white light or any colour.

From Nature 24 April 1913