Greater sensitiveness in the paper,
A good black tint, and
Greater freedom from spots and blemishes, all very material merits.
C. E. F.
[Our Correspondent has forwarded five specimens, four of which are certainly very satisfactory, the fifth is the one prepared by brushing.]
Replies to Minor Queries.
The Groaning Elm-plank in Dublin (Vol. viii., p. 309.).—Dr. Rimbault has given an account of the groaning-board, one of the popular delusions of two centuries ago: the following notice of it, extracted from my memoir of Sir Thomas Molyneux, Bart., M.D., and published in the Dublin University for September, 1841, may interest your readers:
"In one of William Molyneux's communications he mentions the exhibition of 'the groaning elm-plank' in Dublin, a curiosity that attracted much attention and many learned speculations about the years 1682 and 1683. He was, however, too much of a philosopher to be gulled with the rest of the people who witnessed this so-called 'sensible elm-plank,' which is said to have groaned and trembled on the application of a hot iron to one end of it. After explaining the probable cause of the noise and tremulousness by its form and condition, and by the sap being made to pass up through the pores or tubuli of the plank which was in some particular condition, he says: 'But, Tom, the generality of mankind is lazy and unthoughtful, and will not trouble themselves to think of the reason of a thing: when they have a brief way of explaining anything that is strange by saying, "The devil's in it," what need they trouble their heads about pores, and matters, and motion, figure, and disposition, when the devil and a witch shall solve the phenomena of nature.'"
W. R. Wilde.