Units of paper quantity size and type of paper being sold. Reams of 500 sheets (20 quires of 25 sheets) were known in England in c1594; in 1706 a ream was defined as 20 quires, either 24 or 25 sheets to the quire. In 18th- and 19th-century Europe, the size of the ream varied widely. In Lombardy a ream of music paper was 450 or 480 sheets; in Britain, Holland and Germany a ream of 480 sheets was common; in the Veneto it was more frequently 500. Some paper manufacturers counted 546 sheets (21 quires of 26 sheets). J.S. Bach's manuscript paper at Weimar
Drilling formula sheets Drilling formula sheets Drilling Formula Sheets is a set of Drilling Formulas used commonly by drilling engineers in the onshore and offshore oil drilling industry. They are used as part of a key piece of engineering work called Well Control. These formulas are part of the teachings of all well control schools and well engineering schools and for many years have been available from the American Petroleum Institute (API). The formulas from Skynet Labs are currently available in several formats, such as Excel sheets, smart phone app and HTML5 web. The formulas otherwise are available in several well control handbooks.