. Report of the Expedition to Castellon de la Plana, Spain. ut 4 feet. The one at the narrow end carried the object-glass, immediately in front of which was the platform for supporting theprism. At the wider end an adjustable sliding box, divided into a largeand small chamber by an inner partition, fit into the outer mahoganylining; a repeating back, into which the plate-holder fitted, was attachedto the larger of these chambers, whilst the smaller chamber was providedwith ground glass at the camera end, the other end being open to the object-glass ; the use of this latter portion is explained
. Report of the Expedition to Castellon de la Plana, Spain. ut 4 feet. The one at the narrow end carried the object-glass, immediately in front of which was the platform for supporting theprism. At the wider end an adjustable sliding box, divided into a largeand small chamber by an inner partition, fit into the outer mahoganylining; a repeating back, into which the plate-holder fitted, was attachedto the larger of these chambers, whilst the smaller chamber was providedwith ground glass at the camera end, the other end being open to the object-glass ; the use of this latter portion is explained below. For making the exposures a balanced double-flap shutter was designed; 1905.] Eclipse Expedition to Castellon de la Planay Spain. 25 this was contained in the larger chamber, a few feet in front of the plate,and was operated by a lever. As explained previously, it was intended that the prism should be drawnin front of the object-glass at the beginning and towards the end of totality, Fig. 8.—Camera end of 40-foot Coronagraph and Prismatic a. Eepeating back and dark slide. b. Ground glass screen for observation of less refrangible part of spectrum. c. Handle for operating exposing shutter. when photographs of the coronal and flash spectra were to be taken onplates 6 x 15 inches, the longer edge being in the direction of length of photographic plate was only sufficient to include the spectrumfrom about Hp to some part in the ultra-violet, and the visible portionof the spectrum fell on the ground glass attached to the small chamber onthe right of the plate-holder; hence the spectroscopic phases of the eclipse 26 Profs. H. L. Callendar and A. Fowler. [Oct. , could be visually observed and simultaneously photographed ; by this meansit was anticipated that the flash spectrum might be secured both at thebeginning and end of totality. During the greater part of totality theprism was to be removed, and photographs of the corona obtained on plates12 x
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