"Frutex," Philadelphia, writes: " In one of Dr. Rothrock's Fairmount Park Lectures it is stated that there was provision made by William Penn, July 11th, 1681, ' that in clearing the ground, care be taken to leave one acre of trees for every five acres cleared, especially to preserve the oak and mulberry trees for silk and shipping.' It would be interesting to know in the subsequent sale of Pennsylvania lands, how this healthful provision came to be abrogated. There is much in the agrarian and arboreal history of our State that would perhaps be of interest if it could be brought out".