A pair of contact springs are slowly shifted over so as to close the circuit at successive assigned instants during a complete phase.
In the instants when a sharp image of the photosphere is seen or photographed, it shows a granulated appearance like white flakes strewed fairly evenly upon a dark ground.
The instants of contact between the limbs of the sun and planet defied precise determination.
A few instants after the echo of the reports resounding over the stone- built Kremlin had died away the French heard a strange sound above their head.
2940, Dr Repsold proposed a method of meridian observing which consists in causing a web to follow the image of a star in transit by motions communicated by the observer's hands alone, whilst electrical contacts on the drum of the micrometer screw register on the chronograph the instants corresponding to known intervals from the line of collimation.