Portrait of a Killer: Jack the Ripper—Case Closed that a paper manufacture expert she hired asserts that reams of paper supposedly used by Jack the Ripper to write several letters to Scotland Yard and paper purchased by Sickert's mother bear the same small-press watermark. She also claims that there are matches in the cutter's marks, which are a result of the rough cutting of each quire (or small package) for packaging. A "quire" was usually of 24 sheets. Though Cornwell's book sold many copies, many Ripperologists and other critics argued that Cornwell's theory was far from persuasive. Critics also note that Cornwell has said that she did not
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.