377 
ON THE TOTAL ECLIPSE OF THE SUN, MAY 28, 1900. 
Part I.— General Arrangements. 
By Sir Norman Lookyer K.C.B., F.R.S. 
Objects of the Expedition. 
The discussion of the series of photographs taken with the prismatic cameras 
employed in the last three eclipses indicated that continued work with this form of 
spectroscoj)e should Ije undertaken, with the view (l) of obtaining data strictly 
comparable with the previous photographs, and (2) of extending the inquiry into the 
comparative lengths of the various arcs. 
For the first jDurpose it seemed desirable to repeat the Indian work with the 6-inch 
camera having two prisms ; while for the second an instrument of longer focus was 
necessary. 
Representations as to the importance of the latter instrument were made to the 
Royal Society, and ultimately the purchase of a Taylor triple lens, of 6 inches aperture 
and 20 feet focal length, was authorised. 
With these instruments it was hoped to obtain a very complete record of the 
spectra of the chromosphere and corona, and to obtain data relating to the distribu¬ 
tion of different substances. 
For comparison with the spectroscopic pictures of the corona given by the 
prismatic cameras, it was considered desirable to attempt to secure direct photo¬ 
graphs of the corona with instruments having lenses of focal lengths nearly the same 
as those of the prismatic cameras, and arrangements were accordingly made to use 
coronagraphs of 16 feet and 8 feet focal length for this })urpose. Other coronagrajjlis, 
of shorter focal length, were also provided, in case sufficient assistance should he 
available to enable them to be used, more particularly with the view of photographing 
the coronal extensions. 
Some importance was also attached to visual telescopic observations of the inner 
corona, in order to determine whether the filamentary structure observed in the 
eclipse of 1871 , at a time of maximum sun-spots, was also a feature of the inner 
corona at a time of sun-spot minimum. 
A comprehensive programme of observations of the general phenomena of the 
eclipse was also arranged. 
The Observiny Station and Preparations. 
The observing station selected for my party was determined upon from information 
supplied by the Hydrographer, Rear-Admiral Sir W. J. L. Wharton, R.N., K.C.B., 
F.R.S. Santa Pola appeared likely to meet the requirements of a man-of-war; and 
without such assistance as a man-of-war can render, the manipulation of long focus 
prismatic cameras in eclipse observations in a strange country is impracticable. 
VOL. oxcvni.—A. 3 c 
