1 The Birth of Science - MSRI

11.2 The Renaissance 301
tic works that survived down to the Renaissance still exist today, or that
those that exist have all been published or are even necessarily known.
An annotation by Leonardo in Codex L of the Institut de France contains
the sentence “You will get through Borges the Archimedes from the bishop
of Padua and through Vitellozzo the one from the village at San Sepolcro.”
43 Some of Leonardo’s sources on Archimedes must have contained
information now lost: for instance, he describes and draws an otherwise
unknown steam cannon (the architronito, or “mega-thunder”), crediting it
to Archimedes, 44 and he knows biographical details concerning a stay of
Archimedes in Spain 45 and concerning his tomb 46 of which we have no
other record.
There is more in Leonardo’s manuscripts that seems to be based on now
vanished sources. It would be nice to find out, for example, where he read
about the magnification of faraway objects and the possibility of building
an instrument that could be used to study the features of the moon’s sur- page 372
face. 47 Perhaps his source was the same that allowed Girolamo Fracastoro,
a bit later (1538), to be more specific and say that this is done with two
lenses, not least because Fracastoro too (a physician, poet and humanist)
talks about using the instrument to observe the moon. 48 What is certain is
that neither author was able to describe in detail, and much less build, the
telescopes of which they write.
Mechanical technology, too, continued to move forward in the sixteenth
century, with the building for amusement of various self-propelled mechanisms
(which gave rise to such things as clocks with jackwork) and the
reproduction of ancient devices, like the differential gear, which were to
be of great importance to productive technology. 49
43 Codex L of the Institut de France, 2a = [Leonardo/Richter], vol. II, p. 428.
44 The passage is quoted by Gille, who adds: “Such experiments . . . led Leonardo to conceive
the war engine he called the architonitro, whose paternity he attributes to Archimedes, for reasons
not too clear. It seems this was simply the same as the famous seventeenth-century experiment of
making a cannon shoot by filling it with water and heating” ([Gille: IR], p. 179).
45 Codex Ashburnham 2037 (ex codex B), 12 b = [Leonardo/Richter], vol. II, p. 451. Trips of Archimedes
after his return from Egypt, not known from any ancient source presently available, are also
mentioned by Torelli in his biography of the scientist at the beginning of [Archimedes/Torelli].
46 Codex Arundel (British Museum), 279 b = [Leonardo/Richter], vol. II, p. 446.
47 Codex E of the Istitut de France, 15b = [Leonardo/Richter], vol. II, pp. 140–141.
48 “Per dua specilla ocularia si quis perspiciat, alteri altero superposito, maiora multo et propinquiora
videbit omnia” (G. Fracastoro, Homocentrica sive de stellis, II, viii); the reference to the moon
is in III, xxiii. This is the book where the author puts forth Eudoxus of Cnidus’ theory of concentric
spheres.
49 The first application of differential gears in production (to a threading machine) came centuries
after the introduction of the same mechanism in astronomical clocks. Any doubt that it was an independent
reinvention rather than the resumption of Hellenistic knowledge disappears when we
observe that in sixteenth-century astronomical clocks differential gears were employed to transform
synodic months into sidereal months, the exact same use to which they were put in the
Revision: 1.11 Date: 2003/01/06 07:48:20