ioo Williamson. — Action of Wood on Photographic Plates. 
Bibliography. 
1. Russell, W. J.: The Action of Wood on a Photographic Plate in the Dark. Philosophical 
Transactions of the Royal Society, 197 B, 1904. 
2. Groom, Prof. P., and Rushton, W. : Structure of Wood of Indian Species ot Firms. Journal 
of the Linnean Society, vol. xli. 
EXPLANATION OF PLATE XI. 
Illustrating Miss Williamson’s paper on Some Experiments on the Action of Wood on 
Photographic Plates. 
Fig. 1. Print from negative from sample of Oak, showing the spring wood dark, autumn wood 
light, and medullary rays light. This is the reverse of the negative. 
Fig. 2. Specimen 260, Scotch Pine, which had been subjected to ioo 0 C. for two days some 
months previously. The negative gave the spring wood dark and the autumn wood light, so the 
reverse is shown in the print. 
Fig. 3. Larch. The negative gave spring wood light and autumn wood dark, so in the print 
there are broad dark rings in the position of the spring wood and narrower light bands in the 
position of the autumn wood. Cf. Fig. 2. 
Fig. 4. Scotch Pine, Specimen 321. 
Fig. 5. Scotch Pine, Specimen 191. This specimen showed broad bands of both spring and 
autumn wood. The paper indicators showed that this gave a negative of the Larch type. Cf. Fig. 3. 
Fig. 6. Scotch Pine, Specimen 191, which had been subjected to ioo°C. for two days some 
months before the negative was obtained. This follows the general rule for Scotch Pine, as in Fig. 2, 
and is the reverse of Fig. 6, 
Fig. 7. Scotch Pine, Specimen 471, air-dried. This is again the Larch type of image, as in Fig. 3. 
Fig. 8. Scotch Pine, Specimen 283, air-dried. This follows the normal rule for Scotch Pines — 
spring wood active and autumn wood inactive. 
Fig. 9. Scotch Pine, Specimen 283, previously heated to ioo°C. for two days. This shows 
a negative with spring wood inactive and autumn wood active. 
