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SMITHSONIAN CONTRIBUTIONS TO KNOWLEDGE 
VOL. 27 
measures 5 feet, 5.7 inches, or 3 inches less than when fully extended in the hori- 
zontal plane. 
5. The position of the center of pressure of the wing. — This is indicated on 
two compo-board patterns, C and D. C was made from a fully extended wing, 
while D was made from the wing in the soaring position. The centers of pressure 
of the wings are about 2 feet, 0.5 inches apart, or 1 foot, 0.25 inches from the 
central point of the bird’s body. 
6. The position of the center of gravity of the soaring bird. — (Length of 
buzzard, 26 inches.) The center of gravity of the soaring buzzard in the hori- 
zontal plane, CG lf was found to lie 9^ inches behind the tip of the beak and 16^ 
inches in front of the tip of the tail. 
The center of gravity of the soaring bird in the vertical plane, CG 2 , was 
found to lie 2.8 inches above the ventral point of the body and 1.6 inches below 
the dorsal point, the depth of the bird’s body at CG X being 4.4 inches. 
In determining the center of gravity, the bird was frozen in the soaring 
position, its wings making a dihedral angle of 150°. It was then hung up, first 
horizontally and then vertically, and balanced till the line from which it was sus- 
pended coincided with a plumb-line placed in front of it ; the measurements were 
then made. 
The bird was afterwards, and while still frozen, hung up in the same way 
in Mr. Smillie’s photographic room, and exposures made by him in both posi- 
tions. These photographs, E 1 and F 1 were enlarged to natural size, and meas- 
urements made on the enlargements yielded, as nearly as could be determined, 
the same results as when taken directly upon the bird. 
As determined by measurements upon the buzzard in soaring position, the 
er of gravity was found to be 2.65 inches below the center of pressure (esti- 
ag the center of pressure to be at the bend of the wing) ; or, employing the 
compo-board pattern in a corresponding position, the distance was seen to be a 
small fraction of an inch less. 
7. The position of the root of the wing. — This is indicated on the tracing A x . 
a. (Depth of the body on a vertical line with root, 3.5 inches.) The root lies 
1.6 inches below dorsal line, 1.9 inches above ventral line. 
b. (Length of body, 26 inches.) The root lies 7.6 inches behind tip of beak, 
18.4 inches in front of tip of tail. 
8. The dihedral angle between the icings. — The photographs taken previ- 
ously were not sufficiently large or distinct to enable us to determine this with 
exactness. It was estimated, however, as 150°, and experiments were made on 
this basis. 
9. The center of gravity of the dissected wing.— This was found, first, for 
the wing having all the muscles, up to the ball and socket joint, intact. One of 
the wings was frozen in the soaring position and its center of gravity found by 
balancing on a point. Its position was marked by a wire thrust through the 
wing at this place, and the wing (H) is preserved in formalin. This position 
is also marked on a special tracing, I. It lies 6 inches from the base of the 
humerus bone (root of wing). Secondly, it was found for the wing denuded of 
all muscle. Its position was marked on the other wing of the bird, which is pre- 
served dry, spread in the soaring position. It lies 9f inches from the base of the 
humerus. 
