OCR Text |
Show Photographic Power of Wood. Experiments recently made have shown that a section of a tree trunk or of a branch, cut across the grain, possesses the power to impress upon a photographic plate in the dark a distinct dis-tinct image of itself, plainly showing the rings of growth. There is a great difference in the intensity of this power pow-er among different kinds of wood. The conifers (pines and firs) possess it In high degree. The wood is placed either eith-er in contact with the pate or at a short distance from it, and the exposure ex-posure varies from half an hour to 18 hours. Boards long exposed to the air, an oak box 100 years old, rotten wood from a stump, and even bog-wood, bog-wood, have been found still photographically photo-graphically active. |