Decemser 6, 1918] 
time intervals and so strictly rhythmical in 
character. Georce H. Hupson 
PuaTrsBurGH, N. Y. 
ALLEGED REDISCOVERY OF THE PASSENGER 
PIGEON 
In Science for Noyember 1 is a communi- 
cation under the caption “ Alleged rediscovery 
of the passenger pigeon,” in which the state- 
ment is maintained that a flock of this sup- 
posedly extinct bird was recently seen in New 
York state. Among other observations offered 
in support of the identification, mention is 
made of “the whistling sound of their wings.” 
During the seventies and early eighties it was 
my privilege to form an intimate acquaintance 
with the passenger pigeon, seeing many thou- 
sands of them, shooting hundreds of them and 
finding numerous scattered nests in the vicinity 
of Minneapolis, Minn. The wings of this bird 
never “ whistled,” the sound made in taking 
flight being a flapping or fluttering noise sim- 
ilar to that made by the tame pigeon. A 
flock in rapid flight made a rustling or swish- 
ing sound as it passed through the air. On 
the other hand it is a well-known fact that the 
wings of the mourning dove produce a loud 
characteristic “ whistling sound ” as it launches 
itself into the air and until it gets well under 
way. Among pigeon hunters in the old days, 
this was a commonly recognized distinguish- 
ing feature between the two species when other 
means were obscured. 
In and about a “buckwheat field” is an 
ideal place for an assemblage of mourning 
doves. Passenger pigeons also fed on grains 
of various kinds, chiefly wheat and oats, but 
their favorite food was thin-shelled nuts, 
largely acorns here in the north. 
In view of the fact that no reports of the 
passenger pigeon from experienced ornitholo- 
gists have been received for a considerable 
number of years, in spite of persistent search, 
it would seem as though this bird must be re- 
garded as an extinct species. 
Tuos. S. Roperts 
ZooLoGicaAL MusEuM, 
UNIVERSITY OF MINNESOTA, 
November 20, 1918 
SCIENCE 
575 
DEMONSTRATIONS OF VISUAL PHENOMENA 
PURKINJE EFFECT 
Ir a color wheel with a reddish and a bluish 
color be spun in the light of a strong lantern, 
and then slowly have its plane turned until 
the incidence of the light is just grazing, the 
Purkinje effect is at once demonstrated to a 
class. As the angle of incidence changes 
from normal to grazing, the intensity of illu- 
mination is reduced to zero, and the red be- 
comes invisible. The effect of this is in gen- 
eral to change the. apparent color of the dise 
through a series of very pretty shades. 
PERSISTENCE OF VISION 
This is easily shown to a class by means 
of a lantern, with a slide bearing some letters. 
Instead of imaging the slide on a white sur- 
face, the image should be absorbed by black 
velvet or the image may be formed in an 
open doorway. Now move a fairly white stick 
vertically down in the plane of the image. 
Different portions of the image can then be 
seen on the stick, and if the stick be moved 
fast enough, the eye sees the entire image 
easily. 
Pau F. Garur 
WELLS COLLEGE 
USONO 
To THE Epiror oF Science: In connection 
with the discussion in your columns as to a 
more specific name for our country than 
“ America,” it may be interesting to note that 
the advocates of the international language, 
Esperanto, solved this problem so far as they 
were concerned quite a while ago, by the adop- 
tion of the name “ Usono.” This is the sub- 
stantive form of the expression US 0 NA., com- 
posed of the initial letters of this nation’s full 
designation. Usona is, in Esperanto, the ad- 
jectival form. 
In a rather hasty and superficial glance 
through the back files of Esperanto publi- 
cations, I find the word used, either in the 
text or in date lines, titles, etc., in various 
magazines, books and pamphlets issued in Eng- 
land, France, Germany, Poland, Switzerland, 
