Exhibits.—1. Photograph of Prismatic Solar Spectrum, photographed by Mr. Ives, of Philadelphia, U.S., on an Ives’ Chlorophyl-Eosine plate.
The negative was made with minimum exposure and forced development, to show the strongest possible contrasts. The action in red and orange is due solely to chlorophyl, that in yellow-green about one-third to chlorophyl and two-thirds to eosine, that in dark-green chiefly to chlorophyl. The visible spectrum appears strongest in deep red and weakest in blue—the exact reverse of an ordinary photograph in this respect, and a result which cannot be secured with any but a chlorophyl process. This was exhibited by Ven. Archdeacon Stock, who received it from C. Piazzi Smyth, Astronomer Royal of Scotland. Professor Piazzi Smyth, in sending this, remarks that with this photo-material sunsets may be photographed brilliantly; and peaches and oranges will come out brighter than the green leaves they are amongst.
2. The Marimba, or African piano.
This instrument was obtained from the Zulus, but, with various modifications, it is found in many parts of South Africa.