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SCIENCE 589
nomy and cosmology through discussions of meteorology,
optics, the magnet, chemistry, fossils, zoology, botany, and
physiology. Later in the century, John Pecham wrote an ad'
mirable short textbook on optics, and in the first half of the
fourteenth century John of Dumbleton, at different times a
fellow ofMerton and of Queen's Colleges at Oxford, tried to
formulate the mathematical law relating intensity of light to
distance from the source.
Throughout the middle ages meteorology formed a single, if
heterogeneous, subject with optics, mainly because both were
discussed in Aristotle's
Meteorology and medieval scientists
habitually published their original
results in the form of conv
mentaries on Aristotle and other authorities. Moreover, comets
were regarded as meteorological phenomena, belonging to the
region below the moon. Grosseteste seems to have observed
'Halley's comet* in 1228, and he used his method offalsification
in an interesting discussion oftheories ofcomets. Roger Bacon
also described a comet seen in July 1264, and attributed to its
influence various distressing political consequences. Another
meteorological phenomenon studied with interest in medieval
as in modern Engknd was the weather. A most remarkable
series of records were kept during 1 3 37-44 f r ^e Oxford dis^
trict by William Merlee, with a view ofmaking predictions
for
farmers. He based forecasts partly on the state ofthe heavenly
bodies, and partly on inferior signs of humidity: the moisten^
ing of salt, the carrying of sound from distant bells, and the
increased activity of fleas.
Other physical problems discussed by Grosseteste in various
special tracts were heat, which he regarded as a mode ofmotion
of particles ofmatter, falling bodies, and astronomy; a mathe^
matical problem that extended into his cosmogony was the
summation of infinite aggregates; and a practical problem on
which he wrote several treatises was the reform of the calendar.
By the beginning ofthe thirteenth century the cumulative in/
accuracy of the accepted Julian calendar had produced gross
errors in the date of Easter, and, as Roger Bacon put it in his
development, in the Opus Majus, of Grosseteste's proposals for