ee 
Report on A. Perrey’s Researches relative to Earthquakes. 57 
it has happened only in one country or on the same identical or 
different hours in two or several countries, separated by intervals 
not participating in the movement. Noting then, after the Con- 
naissance des ‘'emps, to what day of the lunation, each day of 
earthquake corresponded, he brings together in one column all 
the days which pertain to the first day of a lunation; in a second, 
all pertaining to the second day of a Iunation, and so on. Thus 
he forms a table consisting of 30 columns, each column giving 
the number of days of earthquake corresponding to the succes- 
sive days of the moon. The numbers vary, and the law of vari- 
ation is the same in his first table comprising a register of 2735 
days of earthquakes between 1801 and 1845, as in his later one 
embracing 5388 days between 1801 and 1850. In both tables, 
the number of earthquakes during days near the syzygies is a little 
larger than in days near the quadratures. 
In his second method, the author regards as distinct, the earth- 
quakes in different regions separated by an undisturbed region, and 
each day of earthquake is counted 1, 2, 3, &c., according as the 
earthquakes of this day were experienced in 1, 2 3, &c. separate re- 
gions. By this new mode of tabulating, the number 2735 is 
increased to 3041, and that of 5388 to 6596. The same law is 
observed in these new tables as in the first set: and similar also 
is the result obtained by dividing the half century into two quar- 
ter centuries. 
considering by this method 931 shocks felt in Ceutral America 
and mostly at Arequipa, as published by M. de Castelnau in the 
Sth volume of:his “ Voyage dans les parties Centrales de l’Amer- 
ique du Sud.” This table, without giving identical results with 
the proeting, leads to the fundamental relation already men- 
tioned. 
Finally, in-the fourth method of arrangement, the application 
of which is difficult and has not yet been made by M. Perrey, the 
collection of shocks in a country, preceded and followed by a 
period of tranquillity is regarded as a single phenomenon. 
To the nine tables formed by one or the other of the first three 
methods of tabulating, the author has added a tenth, formed by 
the first mode: it embraces four years, from 1841 to 1845, and 
only 422 days of earthquakes. Although this number is small 
the numbers lead to the same general conclusion—that is, the 
greater frequency of earthyuakes at the syzygies than at the 
quadratures, eae 
Szconp Serres, Vol. XIX, No. 55.—Jan., 1855. 8 
