THE REGISTER, 41 



In calculating all these different results, we should take, in 

 order to be very exact, the means of the sums of all the observa- 

 tions during the i^eriod of time in question, by reason of the 

 inequality of the length of the months. 



The sums which form the basis of all these means should be 

 inscribed in the tables in the place reserved for them. 



The preceding calculations, after a little practice, will not ap- 

 pear difficult, and may be quickly performed ; but it can hardly 

 be too often urged upon the observer to make them without 

 delay ; otherwise, this task, which is slight if accomplished daily, 

 would become very heavy, if left to accumulate for several 

 months. It is only by making the correction himself that the 

 observer can institute his own comparisons, and really study the 

 course of the meteorological phenomena. His interest will in- 

 crease still more with the feeling that he is cooperating in a 

 great work, which concerns at once his whole country and the 

 science of the world, and the success of which depends upon the 

 accuracy, fidelity, and devotion of all who take part in it. 



A copy of the observations of each month must be forwarded 

 during the first week of the following month. It should be 

 carefully collated by two persons, one of whom reads the figures 

 aloud. Each observer will receive for this purpose a double 

 series of blank forms, one of which will be retained by him. 



Many of the phenomena connected with the state of the at- 

 mosphere are of great interest for comparative climatology, 

 especially in a practical point of view. The periodical pheno- 

 mena of vegetation and of the animal kingdom, such as the 

 epoch of the appearance and the fall of the leaves, of the fiower- 

 ing and ripening of the more generally cultivated fruits; the 

 seed time and harvest of plants: the coming and going of mi- 

 gratory birds ; the first cry of the frogs, the appearance of the 

 first insects, &c. ; the moment of the closing of rivers, lakes, 

 and canals by ice, and of their opening; the temperature of 

 springs at different periods of the year; the temperature in the 

 sun compared to that observed in the shade; that of the surface, 

 and that below the surface of the ground. All observations of 

 this kind are valuable. 



The observer will find it very instructive to project curves 

 which indicate the diurnal, monthly, or annual variations of tern- 



