Nails
2 of the 7 encyclopedias on this shelf carry an entry for Nails. Both are reproduced below, so you can see where they agree and where they differ.
Collier's New Encyclopedia (1921)
flattened, elastic, horny plates, which are placed as protective coverings on the dorsal surface of the terminal phalanges of the fingers and toes. Each nail consists of a root, or part concealed with a fold of the skin; a body, or exposed part attached to the surface of the skin; and a free anterior extremity called the edge. The skin below the root and body of the nail is termed the matrix, from its being the part from which the nail is produced. This is thick, and covered with highly vascular papillæ, and its color is seen through the transparent horny tissue. Near the root the papillæ are smaller and less vascular; hence the portion of nail corresponding to this part of a whiter color; from its form, this portion is termed the lunula. It is by the successive growth of new cells at the root and under the body of the nail that it advances forward, and maintains a due thickness, while at the same time its growth in a proper direction is insured.
The Encyclopedia of Founding (1892)
Formerly all nails were made by hand or forged on the anvil, and large quantities are still produced in this manner in England and other parts of Europe. Nail-making by machinery was originated in Massachusetts in 1810. At present we have machine wrought-nails, cut-nails, and cast-nails. The machine cut-nails are simply wedge-like in breadth, equal in thickness--head and body--to the sheet iron from which they are cut, and these are always to be preferred for strengthening and securing the sand surfaces of moulds, rather than those which have had heads forged on them. The length of iron machine cut-nails and the number contained in a pound will be found in the following table: Size. Length in inches. No. in a pound. Size. Length in inches. No. in a pound. Size. Length in inches. No. in a pound. 3-Penny. 1 1/4 420 6-Penny. 2 175 12-Penny. 3 1/4 52 4-Penny 1 1/2 270 8-Penny. 2 1/2 100 20-Penny. 3 1/2 28 5-Penny 1 3/4 220 10-Penny. 3 65 30-Penny. 4 24 40-Penny. 4 1/4 20