Chapter 4 Halley’s General Strategy for Reconstructing Conics, Book VIII
Whether or not it was deserved—and it may well have been deserved—Halley gives Aldrich the credit for pointing the way on how to reconstruct Book VIII. In the preface to the reconstruction, Halley recounts Aldrich’s observation that “…in Pappus’ Mathematical Collection, [Pappus] himself passed on lemmas serving [what] was to be demonstrated in the seventh and the eighth book of the Conics at the same time; whereas in the other books, different [lemmas] to the different [books] are provided. Hence, to you [Aldrich] we owe the discovery that the [two] books are conjoined; that the problems in [Book] eight are allotted their determination from the theorems on diorisms () in [Book] seven.” Surely, by the time Halley wrote this, he would have known the connection between the contents of Books VII and VIII which Apollonius himself points out in the preface to Book VII, as described above. Still, Aldrich’s observation regarding Pappus may truly have been the trigger that set the project going.