Fractured upper plate along line of rivet holes; silky fractures; metal hard about holes, with small granular spots near punched holes.

Hiron rivets, "Burden's best."

Punched holes: Punch, ".753 diameter; die, ".774 diameter.

Square inches.

3.63

2.24

2.49

4.08

Sharp but not loud report heard at 100,000 pounds and again heard just before fracture of the plate.

Fractured plate across row of four rivet holes; the metal first separated at the middle sections, which displayed in part fine granular fractures and in part silky appearance.

Photograph of fractured plate, showing granular metal, next two rivet holes, radiating

from rivet holes.

Photograph of under plate, Joint No. 83. Appearance after rivets were sheared, showing the development of "Cooper lines."

" iron rivets, "Burden's best."

Punched holes: Punch, 1" diameter; die, " diameter.

Gross sectional area of under plate
Net sectional area of under plate.

Bearing surface of rivets

Shearing area of rivets (".82 diameter)

32

10.08 x 496

Square inches.

4.97

2.84

2.13

2.64