MISCELLANEOUS CIRCULAR 



U. S. DEPT. OF AGRICULTURE 



1 piece of flat iron 1 by 34 by 13 inches, for top cross bar (3). 



2 pieces of flat iron each 1 by 34 by 11 inches, for short cross bars (4). 



2 pieces of strap brass each % by T V by 6 inches, for clasping hooks (14). 

 2 pieces of No. 3 * (34-inch) oil-tempered spring-steel wire, each 8 feet long, for 

 # making the two coil springs (6). 



1 piece of No. 6 1 oil-tempered spring-steel wire, 2 feet long, for trigger spring (8). 



2 pieces of No. 6 oil-tempered spring-steel wire, each 10 inches long, for trigger 



bars (11). 



Fig. 2.— Details of construction of Biological Survey beaver trap 



1. Base bar. 



2. Cross bar. 



3. Top cross bar. 



4. Short cross bar. 



5. Trap jaw. 



6. Coil spring. 



7. Trigger. 



8. Trigger spring. 



9. Trigger wire. 



10. Trigger collar. 



11. Trigger bar. 



12. Hinged trigger loop. 



13. Trigger grip. 



14. Clasping hook. 



15. Wire mesh. 



16. Safety hook. 



1 piece of 1-inch mesh, No. 16 * woven wire, galvanized before weaving, 50 inches 



long from a roll 60 inches wide, for bottom and sides of trap (15). 

 50 feet of No. 15 l galvanized malleable wire, for lacing and linking wire mesh 



sides and floor of trap to jaws and bottom, for making trigger wires (9), 

 _ trigger collar (10), and safety hooks (16), and for fastening trigger spring. 

 30 inches of No. 12 galvanized wire, for trigger (7). 

 5 quarter-inch bolts, four of them % inch long and one 1 inch long, for attaching 



cross bars to base bar. 

 1 pair of 13^2-inch brass hinges with strap-shaped sides, and two screw holes in 



each, for trigger loop (12). 



SHOP WORK 



Brill -^-inch holes as follows: Two side by side. 3 inches from each 

 end of base bar; and one \i inch from each end of long cross bar. 



Drill M-mch holes as follows : One in center and one at 13 inches 

 from each end of base bar; one in center and one 6 inches each side 

 of center of main cross bar; one in center and one Yj inch from each 

 end of 13-inch cross bar; and one in center and one }4 inch from each 

 end of each 11-inch cross bar. 



Drill -rV-inch holes as follows: At 3-inch intervals along flat jaws. 

 3^8 inch from outer edge and to about 4 inches of the ends; one in 

 middle of one trap-jaw bar 10 inches to right of center and one in 

 the other 10 inches to left of center of trap; two in middle of main 

 cross bar at 8 and 9 inches from each end, for hinges for trigger loops. 



1 All wire sizes are standard American gauge. 



