ledged works he refers to Graunt's book as Graunt's and not as his own. Petty in 1660 was too much occupied to write a book demanding such an amount of original investigation. There is no reason given for an unwillingness to acknowledge the authorship on Petty's part. The "Bills of Mortality" contained nothing offensive. On the other hand, the popularity and novelty of the book would certainly have induced Petty to claim it as his own, if he had really been the author. Moreover, between Petty's works and the "Bills of Mortality" there is considerable difference of style, language, opinion, and knowledge. The witness of contemporary testimony is not decisive. The fifth edition of the work, published in 1676, was edited by Petty. His contemporaries might accordingly ascribe the book to him.
This view, however plausibly stated, hardly seems to give adequate weight to contemporary testimony. How are we to reject the following statement of Evelyn:[1] "He (Petty) is author of the ingenious deductions from the bills of mortality, which go under the name of Mr. Graunt."
John Aubrey, whose friendship with Petty was closer than Evelyn's, and who had even a better opportunity than Evelyn for discovering the real author, tells us that the "Bills" was due to him.[2] We are not able to assign a reason for Petty's wish to conceal his authorship under the name of a friend, but we do know that several of his works were published anonymously during his lifetime. The following letter to Aubrey of the 29th of May, 1678, may throw some light on this matter.
"As for the reprinting the book of taxes, I will not
