JuLy 2, 1914] 
NATURE 
of the whole reckoning system refers to a day 
which in this almost perpetual calendar is a 4 
Ahau katun, which begins with the eighth day of 
the score called Kumku. This has therefore been 
called the normal or zero date, from which all the 
monumental dates reckon in days, scores of days, 
years, scores of years, and cycles. Astronomers 
do not seem to have taken up the question whether 
this zero-date, which lies somewhere near 3000 
B.C., may possibly refer to some remarkable plane- 
tary configuration. It may, however, be alto- 
gether fictitious. Very little is known about their 
cosmogony, and it is not known why they should 
have considered themselves in the ninth cycle of 
their world’s history when they constructed the 
Quirigua and Copan monuments. This mode of 
reckoning was still used at the Spanish conquest, 
but as they had not invented a leap-year correction 
they occasionally shifted their new year’s day to 
make the religious feasts tally with the actual 
seasons. But since it is not known when such 
shifts were made, and since the various nations 
did not interpolate alike, none of the numerous 
dates can be determined. 
Most of this American archeology is still in the 
descriptive stage. For instance, the less there is 
known about the reason why the chief deity, or 
hero, Kukulcan or Quetzacoatl, the Great 
Plumed Serpent, is thus represented, the more 
minutely he is described and figured wherever a 
fragment of him is found. We can see that it is 
a snake. But the answer to the pertinent ques- 
tion: Why aserpent? That there is no particular 
reason except that ‘“‘the body of a snake combines 
readily in art with certain characteristic parts of 
other animals,” that it lends itself especially well 
to design and ornamentation, is rather disappoint- 
ing. 
BIRDS AND WEATHER. 
HE difficult question of the influence of 
meteorological conditions on the phenomena 
of bird migration has fortunately been very 
thoroughly studied as regards the British area, 
but we are none the less glad to welcome the 
recent labours of Dr. Defant on this subject. 
Dr. Defant as a meteorologist has submitted to a 
critical examination the data collected some years 
ago regarding the spring arrival in Austria of 
some thirty species of birds. He has selected 
four species for special treatment, and the data 
cover a period of seven seasons (1897—1903). 
The published weather reports have supplied all 
the necessary meteorological data for the corre- 
sponding periods. 
At the outset of his paper Dr. Defant points 
out that, while all meteorological factors must be 
taken into account, the relation of all other con- 
ditions to that of atmospheric pressure renders 
possible a concentrated attention on the latter. 
A comparison of the ornithological data with the 
1 “Der Einfluss des Wetters auf die Ankunftszeiten der Zugvigel im 
Friihling.” By Dr. A. Defant, Vienna. Reprinted from Schwalée, new 
series, vol, ili., 1913, pp. 135-56, and charts. | 
NO. 2331, VOL. 93] 
457 
temperature records gave.a purely negative result, 
no direct relation being discoverable. Dr. Defant 
also rightly insists on the importance of consider- 
ing the weather of the whole of southern Europe, 
the conditions prevailing in the actual area of 
arrival being obviously less important than those 
in the regions immediately to the south through 
which the migrants must pass. 
The spring immigration of the starling and the 
lark are treated together, these species showing 
a detailed similarity in this aspect of their seasonal 
movements. Tables are given showing that 
there is an annual variation both in the earliest 
date of arrival and in the duration of the influx. 
The period of heavy immigration usually lasts 
about eight days and the average date of maxi- 
mum arrival for the seven years was February 23, 
while the average dates for particular years varied 
from February 12 to March 3. 
With the partial exception of one year out of 
the seven it was found that the periods of maxi- 
mum immigration coincided with periods of low 
atmospheric pressure in the west and north-west 
of Europe and higher pressure in the south, south- 
east, or east. These conditions give southerly or 
south-easterly winds in Austria and the countries 
immediately to the south, and usually rising tem- 
peratures. The immigration was all the greater 
when these favourable conditions had been im- 
mediately preceded by a prevalence of high pres- 
sure in the north and north-west (or north-east) 
and low pressure in the east or south-east; such 
conditions usually entail low temperatures and 
northerly or north-westerly winds. 
Dr. Defant then considers the average daily 
pressure for the three regions into which he 
divides southern Europe. These are A =western 
Asia Minor, the Balkan Peninsula, the Adriatic 
Sea, and southern Italy; B=the remaining greater 
part of Italy, the western Mediterranean and 
northern Africa; and C=Spain and Portugal. 
The last-named region is soon shown to be irre- 
fevant, and Dr. Defant’s second conciusion results 
from a comparison between A and B. He finds 
that strong immigration in Austria occurred when 
the pressure in these regions was relatively higher 
than on the days immediately before and after 
and when the pressure in A was higher than in B. 
The east to west pressure gradient thus formed 
when coupled with the effect of the earth’s rota- 
tion produces the south-easterly winds character- 
istic of the type of weather already described as 
favourable to migration. 
The cuckoo and the house martin are then 
treated in like manner (not jointly as in the pre- 
vious case, but simultaneously to economise space 
in tables and graphs). The same two conclusions 
are arrived at for these immigrations occurring 
much later in the season than that of the starling 
and the lark. A second type of weather was also 
found favourable in the case of the cuckoo, 
namely, extended high pressure over the whole 
of central and southern Europe, usually with weak 
easterly or north-easterly winds. In seasons 
