1927 Transit of Mercury seen from Suffolk with a Cooke

 

Mr. A. F. Bennett: Suffolk

The transit was observed in a perfectly clear sky from 7h 55 m onwards, using the 6-inch Cooke equatorial refractor, first by projection, then by Cooke solar diagonal with eyepiece X 80, and finally, for the concluding phases, X 240. The seeing was fairly steady. The contacts at egress were timed by marine chronometer and " venner " chronograph watch, the chronometer being rated by wireless signals before and after the observation, as follows :. The " Black Drop " phenomenon was very marked and differed somewhat from the appearance observed with exactly the same instruments and eyepiece at the transit of 1924 May 8. On that occasion, a dark and more or less diffused shading appeared between the planet and the Sun's limb just before inner contact.

 In this transit, of 1927 Nov. 10, a dark band or ligament, more certainly defined, seemed to spread between the limb and planet, making the appearance of the latter somewhat pear shaped. Due to atmospheric tremor at the Sun's limb, the time recorded for the last contact cannot be given the same weight as those for the two earlier phases. It is interesting to note that at 8 h 7 m the planet could be glimpsed, just within the limb, when using (as a monocular) one half of a pair of ex-Service Dollond inverting binoculars, power X 6, aperture 35 mm., with an orange-tinted dark cap over the eyepiece.