25 
stead of a favorite temperature ranging from 37° to 41°, as was the case 
in March, it is found that from 55° to 60° is the favorite temperature for 
nearly the last wave. Indeed, 63° is about the average temperature at 
which the real rear guard, composed of Cuckoos, Whippoorwills, etc., 
usually moves. 
In cloudy weather there were 184 records, and in clear weather 113; 
or 62 per cent. in cloudy to 38 per cent. in clear weather, as against 60 
and 40 per cent., respectively, in March. The records with relation to 
the wind are as follows: Wind N., 64 records; NE., 0; H.,6; SE., 47; 
S., 49; -SW.,42; W., 23; NW., 33; or for N., NE., and NW., 97; with 
138 for 8., SE., and SW. 
The average barometer for 298 records was 29.88 inches, against 30 
inches in March. 
A STUDY OF THE ‘‘ BIRD WAVES” WHICH PASSED UP THE MISSIS- 
SIPPI VALLEY DURING THE SPRING OF 1884. 
The following study, for obvious reasons, must be considered as an 
experiment, known to be incomplete, and wanting in many essential de- 
tails. The project was not thought of until migration had commenced; 
no instructions were issued to observers to note bird waves; only afew 
sent in any specific notes on the subject, and most of the information 
relating to it had to be picked out of a mass of notes not pertaining to 
the question, and so intimately connected with other themes as to be 
difficult of separation. Under such adverse conditions no attempt 
would have been made to study the bird waves were it not for the ex- 
treme importance of the subject. It is during the nights of bird waves 
that the bulk of migration takes place. This is especially true of fall 
migration, though to a large extent of spring also. To study migration 
successfully it must be studied when most active. Moreover, it is on 
bird waves that the action of the weather is most apparent; hence, these 
waves furnish the readiest means of studying the relation between me- 
teorology and migration. The greatest drawback is met with in the 
difficulty of accurately observing and reporting bird waves. It is by 
far the hardest part of the field work in the study of migration, and 
requires more time and more constant presence in the field than most 
observers can give. 
The only station at which the successive bird waves were accurately 
and fully noted was that at Saint Louis, Mo, where Mr. Otto Wid- 
mann, the most careful, competent, and painstaking observer in the 
district, spent nearly the whole time in the field. For the present, 
then, all that can be done is to take the bird waves of Saint Louis as a 
text and see how far they extended, and how the movements of birds 
at other places agreed with them. From the absence of material, it 
will be impossible to study all the waves of the Mississippi Valley. 
Those observed at Saint Louis will be given in full, not only to serve 
