c. Weight per yard.
d. Tensile strength.
e. Amount of stretch.
f. Amount of friction developed by rubbing two pieces of cloth together.
This test was made because the friction developed in taking a book from between two others is an important matter when a shelf is full of books. If the friction is great the wear on the back of the book is correspondingly excessive.
g. Endurance when folded back and forth in the same place.
h. Endurance under extraordinary conditions of rubbing.
Some of these qualities, such as tensile strength, amount of stretch, etc., were comparatively unimportant, but the tests for all were severe and contributed much to our knowledge of the qualities which should enter into the composition of durable book cloths.
After a very careful consideration of the results of the tests and a thorough examination of the samples submitted, a committee of librarians and government officials unanimously chose three samples as the best of all those submitted by the manufacturers. Of these three samples the cloth numbered 666 was considered the most satisfactory.
Although these three samples were excellent, they all had one defect—the color was pressed in by machinery, not dyed in the piece. After various experiments had been made by the manufacturers this defect was remedied. The Government Printing Office then advertised for bids on cloths which would meet the Specifications drawn up by the Bureau of Standards (See Appendix A). Since that time all the Government documents which continue the old sheep-bound set have been sent to depository libraries bound in cloth made according to these specifications.