Table VIII contains the colour measurements of five sets of screens for trichromatic colour work which have come from time to time under the writer’s notice.
The measurements are the tintometrical colour units required to match the screens under daylight conditions, and are classified under the theoretically accepted terms of Red, Green and Violet.
TABLE VIII.
| Set. | Red Screens. | Green Screens. | Violet Screens. | ||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
| No. | Red. | Or. | Vi. | Light. | Yel. | Green. | Or. | Light. | Blue. | Green. | Black. |
| 1 | 119·0 | — | — | 1·6 | 27·0 | 36·0 | — | 9·0 | 32·0 | 1·4 | 6·6 |
| 2 | 24·2 | +·8 | — | — | 8·9 | — | ·1 | — | 13·0 | — | 3·1 |
| 3 | 26·4 | — | ·8 | — | 7·5 | — | 1·4 | — | 16·6 | — | 3·2 |
| 4 | 22·6 | — | — | — | 7·6 | — | 1·4 | — | 15·3 | — | 3·1 |
| 5 | 21·0 | — | 9·0 | — | 28·0 | 14·0 | — | — | 28·0 | — | 2·8 |
The Red screens are all practically pure except No. 5, which transmits also 30 per cent. Violet. No. 1 is distinguished by its greater colour depth and purity, the degree of which latter is recorded at 1·6 light units brighter than standard.
In the Green division, only Nos. 1 and 5 transmit any green, No. 1 transmitting also 42·8 per cent. yellow and being 9·0 units brighter than standards; No. 4 transmits 66·6 per cent. yellow to 33·3 per cent. green; Nos. 2, 3 and 4 are all yellows tinged with orange.
In the Violet division, Nos. 2, 3, 4 and 5 are all pure blues; No. 1 is tinged with green.