10 



5. These data were worked out on the base of the geographical 

 net and each degree of latitude was divided in two halves zones; 

 the elements were distributed on the squares thus obtained, and 

 combined. This procedure was called the ,,Zonesystem" and it 

 served as a basis for the meteorologist also. 



6. In order to establish all possible uniformity, the mean date 

 mere taken as average ones and that in such a way that the 

 totality of data was added up and the mathematical mean taken. 



The formula applied is the following: if a,, a 2 , a 3 . . . a n are 

 the data and their number, the mean results from the formula 



a, + o 3 4- fl, + "n 



n 



1. The meteorologist worked on the basis of the weather 

 charts of Europe and the special reports issued for Hungary. 



8. As the geographical starting point was of great importance 

 for the progression of the advance, the H. C. O. accepted the 

 meridian of Ferro, for the simple reason that its line does not 

 intersect any of the European countries and consequently none of 

 them are severed off; on the contrary the meridian of Greenwich 

 cuts off one part of England, even London, the western part of 

 France and the whole Iberian penninsula. From Ferro the whole 

 eastern progression can be counted uninterruptedly, a fact which 

 renders matters much more simple. 



At the meeting held in 1899, at my initiative, at Sarajevo, 

 Hungary, Austria and the occupied provinces of Bosnia and Her- 

 zegovina came to an arrangement, which only the H. C. O. carried 

 out without intermission. 



As a matter of course, the weather, the culmination, the 

 direction of flight taken by the masses were to be indicated as 

 far as possible. 



In order to determine whether the advance is made in a 

 broad front or on definite limited roads, an observation en masse 

 of the chimney-swallow was carried out in Hungary in 1898. 



Besides the ordinary system at the disposal of the H. C. O., the 

 masters of elementary schools were recruited; the results were, 

 for the spring of 1898 not less than 5903, and for the autumn 

 of the same year not less than 2366 data. 



