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reasonable hope of obtaining our end, we will neces- 
sarily, first: have to consider either the rainfall of the 
whole of the earth, or at least of large areas, for it is 
well known how much the rainfall may differ in different 
localities. That is, we will have to collect our data at 
a great number of different places. Meteorologists are 
so well convinced of this that for the British Isles alone 
they have over 2200 rainstations and they still complain 
that this number is hardly sufficient. Second: In 
order that any regularity, if it exists, may show itself 
clearly, we needs must have eafensive series, series 
extending over more than a century, probably over many 
centuries. Now such series do not exist in meteorology. 
There are 2 or 3 somewhat long series, but these are 
evidently insufficient. 
Of course the way of the meteorologists is the kingly 
road. If, as no doubt they will, they extend their 
observations to a still greater number of stations, they 
will, in a few centuries, collect materials such as we 
cannot imagine of getting in a different way. But we 
are impatient. In one of his letters Darwin says 
something to the effect that it is quite necessary to collect 
materials for future investigation, but that he has no 
respect for the man who is content to do that and 
nothing else. 
The question in my opinion thus ist Leaving the refined 
investigation of the meteorological data to the competent 
men of the future, cannot we provisionally find another, 
be it far more imperfect, way, independent of any thing 
that is done by the professional meteorologist, to provide 
ourselves with data about the weather, which satisfy these 
two conditions: 
first: of existing for a great number of different localities 
on the earth; 
second: of extending over long series of years. 
