A nice drawing of the rete from Nicephorus Gregoras’s “περὶ κατασκευῆς καὶ γενέσεως ἀστρολάβου” (“On the Mathematical Origin and Construction of the Astrolabe”). This rete, like other diagrams in copies of Gregoras’s text, lacks stars and finer details. In the few copies I’ve seen that include the stars, the rete closely resembles the one surviving […]
Oliver Wendell Holmes could write a thank-you letter. Here he thanks E. D. Cope for sending him a copy of his latest essay. Holmes regrets that he has not yet found the free time to concentrate on Cope’s essay and so has yet to read it, though he looks forward to doing so. Boston, Nov. […]
The Hippiatrica assembles treatments for a wide range of ailments and injuries horses might suffer. The work itself is a collection from various other treatises by authors—e.g., Eumelos, Apsyrtos, Anatolios, Pelagonius, Themnestos, and Hierocles—and was probably assembled sometime between the 5th and the 10th centuries. In this illustration from a 15th-century Italian copy (now in […]
In 1710 the English empiric and author William Salmon published the first volume of his massive Botanologia. The English Herbal. Like most herbals, entries included names of plants, varieties, descriptions, where the plant grew, its qualities (e.g., hot or cold, dry or wet), its virtues, when it flowered, how to combine it with other ingredients […]
This diagram showing the structure of the cosmos comes from Nicephorus Blemmydes’ “Epitome physica.” At the center is the sphere of elemental earth surrounded by a narrow sphere of water. Then a broad sphere of air surrounds them capped by the sphere of fire. Separating the elements from the heaves is the sphere of the […]
The most common type of astrolabe is the planispheric astrolabe, which works by projecting the sphere of the heavens onto a plane in a way that preserves angular distances and allows the user to carry out a wide variety of calculations.[1] The rarest form type of astrolabe is the spherical astrolabe. Although Latin and Arabic […]
This illustration from a 15th-century manuscript seems to be a type of geomantic figure that correlates the planets, signs, and figures (arrangements of dots). It shows the standard astrological relationships between planets and signs. Starting at the top and proceeding counterclockwise from the moon: Moon — Cancer Mercury — Gemini and Virgo Venus — Taurus […]
Jean Tagault was a lecturer in surgery and anatomy at the University of Paris in the mid–16th century. His manual on surgery included not only descriptions of how to perform various procedures that ranged from the relatively trivial and non-invasive to the more cringe-worthy invasive operation. Here he displays a particularly ornate pair of toothed […]
Between 1880 and 1885 Lewis Carroll published ten very short stories in The Monthly Packet, each of which posed mathematical problems. Carroll referred to these stories as “knots” and invited readers to send in answers to the problems in each. Carroll printed the answers he received and at times chided the readers who answered incorrectly. […]
Apollodorus of Damascus is generally thought to have written the “Πολιορκητικά,” a treatise on siege engines, addressed to an unnamed emperor (probably Trajan). The text first treats siege engines used to besiege a hilltop fort, machines to protect troops from objects rolled down the hill as well as devices for protecting men attacking the base […]