If one should ask them how they know that all invoices are charged (or copied into the tissue books) the invariable answer would be, "Oh! we never lose any bills before they are copied." Ask them how they know none are lost and, after thinking a while, they will admit that they really do not know _for sure_. They begin to check back the tissue book after some customer brings in a bill for payment which has never been copied into the tissue book, and hence has not been posted to the customer's account. [Illustration: Fig. 5. Old-Style Copy Press. _Underwood Typewriter Co._ ] Fig. 4 shows the old-style cloth bath, Fig. 5 the old-style copy press, and Fig. 6 the old-style sales book (tissue paper leaves). LOOSE-LEAF SALES SHEETS AND INVOICES This style of billing was the first variation from the plan of using copying ink, or pencil, on invoices and then transferring the ink to tissue paper books, by wetting the leaves with water and then absorbing the surplus water with paper blotters. Or this was done by placing damp cloths on the under side of the leaf and covering it with a leaf, placing the invoice downward on the tissue leaf, closing the book, and placing it in a copying press. The ink from the invoice was sufficiently transferred to the tissue paper to make an impression thereon. [Illustration: Fig. 6. Old-Style Sales Book. _Underwood Typewriter Co._ ] If the person who did the copying did not use due care, the paper would be too wet and the ink would run and blur the copy and the invoice. If two invoices were accidently picked up by the person copying, the top invoice would not be copied on the tissue sheet. This is a most serious objection, for the reason that the copy in the tissue was used as record of the invoice for the purpose of posting into the ledger. Another difficulty was the usual one experienced through the use of bound books in office work. Only one person can use a book at one time. If Fayette Henry, the accountant, was using the tissue-copy book, and Dave Pike, the order clerk, wanted to use it to see if all invoices had been copied by the office boy, he had to wait on Fayette Henry. The loose-leaf sales sheet shown in Fig. 7, with the pages serially numbered and placed in proper binders after each sheet has been filed, overcomes all of the difficulties mentioned—with many additional benefits. [Illustration: Fig. 7. Loose-Leaf Sales Sheet and Invoices. No Ruling on Sales Sheet. _Remington Typewriter Co._ ]