Selections include "Books hitherto published on aerostation" (pages 463-465) and an example of one of the many full-page photo-zincographs that illustrate the text. "Astra Castra is a work of 530 pp. large quarto; it consists chiefly of extract[s] from other works and writings, and it is useful as affording data for a history rather than as a history itself. On pp. 463-465 is a list of books and papers on aeronautics, which seems fairly complete up to the date 1864. . . . We should advise any one desirous of studying the history of aeronautics to consult Mr. Turnor's list in Astra Castra, which is the most perfect we have met with."
- from the article Aeronautics in the Encyclopaedia Britannica, 10th Edition (1902-03).