192 Daily Variations of the Strength of the Wind [April, 
in the mouths of historians, grammarians, and the like. 
Sorely perplexed would these worthies be if called upon to 
show, in the case of any law of Nature such as those we 
have mentioned above, how an exception could “ prove the 
rule.” Indeed the persons who apply this phrase to natural 
questions prove two things, — their inborn or inbred inapti- 
tude for Science, and their ignorance of their own craft. 
For the origin of the saying may be illustrated by the fol- 
lowing examples : — If we find that in some country or at 
some age an especial legislative adt or royal charter was 
necessary, e.g., to enable some man to obtain a divorce, we 
may then conclude that in the rule, in the common course 
of law, divorces were not granted ; and here therefore, and 
in a host of parallel matters, it is rational to say “ the ex- 
ception proves the rule.” But it will be at once seen that 
there is here no possible remotest analogy with anything in 
the laws or rules which we discover in Nature. 
Looking over the fadts brought forward and the considera- 
tions advanced I certainly fail to see how the absolute 
infecundity of animals of different species and the so-called 
‘‘physiological test ” can justify themselves to any candid 
inquirer. 
II. DAILY VARIATIONS OF THE STRENGTH OF 
THE WIND ON LAND AND AT SEA. 
* HE researches of Herr W. Koppen on this subjedt have 
been recently laid before the public in the “ Natur- 
forscher.” 
Though the daily periods of temperature and of barometric 
pressure, as well as a number of other meteorological ele- 
ments, have been for many years the subjedt of close 
examination, it is only of late that the daily period of the 
strength of the wind has been taken into consideration. 
Yet this very feature shows itself more distindtly and gene- 
rally than any other meteorological element, with the sole 
exception of the temperature, and perhaps of relative 
moisture. As will appear below, the daily period of the 
strength of the wind is perhaps even of greater significance 
