Six slips of the sensitized papers were covered by a thin metal plate, pierced by six rows of apertures, a complete row lying over each sample of paper. The rows contained seven apertures each, one being left uncovered to receive the full energy of the impinging light. The remaining six were covered respectively by a Red, Orange, Yellow, Green, Blue or Violet standardized screen of 15 units colour intensity; the whole was fitted into a suitable exposure frame. Many exposures were made, from which the four following were selected:-- No. 1. 20 min. exposure to a dull sky. " 2. 10 " " " bright sunlight. " 3. 20 " " " " " 4. 30 " " " " The results are arranged in Tables VI and VII. Table VII contains results of different exposures under sunlight conditions. TABLE VI. DULL SOUTH LIGHT. 20 Minutes’ Exposure on White Sensitized Papers. -----+-----------------+-----------------+------------------ Pap-| | | ers | OPEN SCREEN. | RED SCREEN. | ORANGE SCREEN. | | | -----+-----------------+-----------------+------------------ | Blk. Or. Red. | Blk. Or. Yel. | Blk. Or. Red. 1 | 7·8 4·2 6·0 | 2·0 4·8 3·0 | ---- ·3 ·2 | | Red. | 2 | 6·0 5·0 5·5 | 1·9 3·1 ·4 | ---- ---- ---- | | Yel. | 3 | 7·8 3·2 7·0 | 2·7 4·7 3·0 | ---- ---- ---- | | Red. | 4 | 7·2 4·3 6·0 | 2·2 3·2 ·2 | ---- ---- ---- 5 | 5·8 7·2 4·0 | 1·9 2·3 ·8 | ---- ---- ---- 6 | 5·6 7·4 4·0 | 1·8 2·6 6 | ---- ---- ---- -----+-----------------+-----------------+------------------