The similar reductions
for the wet-bulb thermometer are rapidly approaching completion.
--Regarding the preparations for the Transit of Venus Expeditions.
Originally five stations were selected and fully equipped
with equatoreals, transits, altazimuths, photoheliographs, and clocks;
but I have since thought it desirable to supplement these by two
branch stations in the Sandwich Islands and one in Kerguelen's Island;
and the additional instruments thus required have been borrowed from
various sources, so that there is now an abundant supply of
instrumental means.... There will thus be available for observation of
the Transit of Venus 23 telescopes, nine of which will be provided
with double-image-micrometers; and five photoheliographs; and for
determination of local time, and latitude and longitude, there will be
nine transits and six altazimuths.... All the observers have undergone
a course of training in photography; first, under a professional
photographer, Mr Reynolds, and subsequently under Capt. Abney, R.E.,
whose new dry-plate process is to be adopted at all the British
Stations.... A Janssen slide, capable of taking 50 photographs of
Venus and the neighbouring part of the Sun's limb at intervals of one
second, has been made by Mr Dallmeyer for each of the five
photoheliographs.
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