Protractograph (Patent No: 286587)

Inventor: Bowen, Orville H.

Location: Robb

Comments: N/A

Description: Orville H. Bowen, Robb, Alberta, Canada, 22nd January, 1929. Filed 17th April, 1928. Serial No. 336,231.

Claim.—1. A drafting instrument including a straight base member, an arcuate base member connecting at its ends with said straight base member near the ends of the latter to provide shoulders at the inner corners of said straight base member, and an arm pivoted to said straight base member with its pivot cutting through the plane of the said shoulders, said arms having a straight longitudinal edge occupying a plane cutting through the centre of the said pivot.

2. A drafting instrument including a flat straight base member having shoulders at its inner corners, said base member having an enlarged central portion with a pivot opening centered on the plane occupied by said shoulders a flat semi-circular base member connecting at its end with the inner edge of said flat straight base member near the ends thereof and having a calibrated upper face and an arm having an enlarged inner end mounted on a pivot pin held in said pivot opening with the main portion of said arm extended tangentially and having a straight calibrated longitudinal edge in a plane cutting through the centre of said pivot pin, said arm also having angularly directed flanges extending from said edge thereof, on opposite sides of said semi-circular base member.

Claims allowed, 2.