THE NATURALISTS' COMPANION. 
92 
built them. The Indians answered 
by saying that, although the tra¬ 
ditions of their people extnded 
back many centuries, neither they 
nor their forefathers knew who 
built them. 
This is a highly interesting ques¬ 
tion, and I hope that archaeologists 
will take hold of and express their 
ideas upon it. 
Near Astoria. Ore., there is a de¬ 
posit of clam shells which covers 
an area of over four acres, and is 
piled in places to a depth of ten 
feet. The amount of shells is in¬ 
calculable. Over a thousand loads 
have been hauled away to make 
roads, but that amount is hardly 
noticed in the diminution of the 
immense heap. From time to time 
relics of the old clam-eating tribes 
that made the place their head¬ 
quarters are found. A party re¬ 
cently found a clam-opener. It 
was made from a whale’s tooth, is 
about eight inches long, and is 
ground sharp at the end. There 
are some sixteen inches of soil on 
top of these immense clam-beds, on 
Avhich grow fir trees, some of them 
four hundred years old. 
THE SOHEimi Blinys. 
In a short paper under this title put 
forward by Mr. 1. Lancaster,of Chicago, 
an attempt is made to explain the equil¬ 
ibrium of soaring birds by the mechan- 
i('al action of currents of air on inclin¬ 
ed planes. A horizontal air current, 
meeting the inclined i)lane of the bird's 
wings, is resolved into two forces, one 
in the direction of the inclined })lane 
and tlie other at right angles to it, so 
that the creature when |)oised in mid- 
air mav b(' said to be continualh' slid¬ 
ing down an upward current of air. Jnj 
test of this theory, practical observa-* 
tions were made on the southwestern^ 
coast of Florida, Avhere soaring birds, 
are someAvhat abundant. On one oc- , 
casion, a score of light gray pelicans , 
rose in the air and floated in the vicin¬ 
ity for several hours, oflering an excel¬ 
lent opportunity for studying their' 
motions. One of the birds had at first 
some ditiiculty in obtaining a position, ■ 
but in the end maintained a steadier i 
]:oise than any of the others. The 
flocdc was about thirty feet distant ; 
from the observer and their Avings wer(‘ 
apparently perfectly rigid. Finally, j 
one of the birds rose steadily in the - 
air at the rate of about ten feet per ^ 
second until a mile or more above the j 
sea. . . . The problem is one of] 
considerable interest, and iiarticulrriy 
if its solution, as seems not unlihely. i 
has any bearing upon the question of; 
aerial navigation. The. exjilanation ■ 
ottered is not satisfactory in several ; 
particulars, for the assumption that | 
the entire force of an aii‘ current is -j 
changed by the bird's surface from 
horizontal to vertical is not wai*ranted, 
nor does it account for the motion oi- 
poise of soaring bii’ds during a period . 
of calm.—SciEXTiFic Amekicax. " 
On the 29th of September, between | 
8 and 9 r. m.. a mirage Avas observed J 
by many persons at ^'^alla in SAveden. i 
The entire loAver part of the nortliAvest- ■ 
ern horizon shone with a lurid glare, : 
above Avhich was a cloud-bank assum- i 
ing the most remarkable forms. From ' 
time to time animals, ti-ees and shruf-.s ; 
Avere seen. Later a group of dancers i 
Avere seen, the men being distinguished | 
from the Avomen. Further north tiu* 
cloud formed an oak forest, in front of ; 
Avhich there was a valley, and nearer 
still a park Avith sanded paths, and at 
about T 80 the cloud sank into a mass 
and the phenomenon disappeared.— 
Nature. 
ShoAv this paper to your friends. 
