Rough Ways Made Smooth: A series of familiar essays on scientific subjects — John Shaqi
Rough Ways Made Smooth: A series of familiar essays on scientific subjectsProctor, Richard A. (Richard Anthony)
Science
Rough Ways Made Smooth: A series of familiar essays on scientific subjects
Proctor, Richard A. (Richard Anthony)
Science
known that in 1666 and 1713 there were no sun-spots. In fact it is
worth mentioning that Cassini, writing in 1671, says, 'It is now about
20 years since astronomers have seen any considerable spots on the
sun,' a circumstance which throws grave doubt on the law of sun-spot
periodicity itself. It is at least certain that the interval from
_maximum_, spot-frequency to _maximum_, or from _minimum_ to _minimum_,
has sometimes fallen far short of 9 years, and has at others exceeded
18 years.
It appears again that certain meteorological phenomena show a tendency,
more or less marked, to run through a ten-year cycle. Thus, from the
records of rainfall kept at Oxford it appears that more rain fell under
west and south-west winds when sun-spots were largest and most numerous
than under south and south-east winds, these last being the more rainy
winds when sun-spots were least in size and fewest in number. This
is a somewhat recondite relation, and at least proves that earnest
search has been made for such cyclic relations as we are considering.
But this is not all. When other records were examined, the striking
circumstance was discovered that elsewhere, as at St. Petersburg, the
state of things observed at Oxford was precisely reversed. At some
intermediate point between Oxford and St. Petersburg, no doubt the
rainfall under the winds named was equally distributed throughout the
spot period. Moreover, as the conditions thus differ at different
places, we may assume that they differ also at different times. Such
relations appear then to be not only recondite, but complicated.
When we learn that during nearly two entire sun-spot periods cyclones
have been somewhat more numerous in the Indian Seas when spots are
most numerous than when the sun is without spots, and _vice versâ_,
we recognise the possible existence of cyclic relations better worth
knowing than those heretofore mentioned. The evidence is not absolutely
decisive; some, indeed, regard it as scarcely trustworthy. Yet there
does seem to have been an excess of cyclonic disturbance during the
last two periods of great solar disturbance, precisely as there was
also an excess of magnetic disturbance during those periods. The
excess was scarcely sufficient, however, to justify the rather daring
statement made by one observer, that 'the whole question of cyclones
is merely a question of solar activity.' We had records of some very
remarkable cyclonic disturbances during the years 1876 and 1877, when
the sun showed very few spots, the actual _minimum_ of disturbance
having probably been reached late in 1877. A prediction that 1877 would
be a year of few and slight storms would have proved disastrous if
implicit reliance had been placed on it by seamen and travellers.
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