FACTORS AND TABLES OF EQUIVALENTS USED IN FORESTRY ils 
TasBLeE 21.—Grades and slopes per 100 feet horizontal—Continued 
DEGREE OF SLOPE AND EQUIVALENT GRADE PERCENT 
| 
Degree of . Degree of Degree of Degree of ca 
Ge at Grade Sone Grade alone Grade ioe Grade 
Oe ig Percent aan) ve Percent oy Percent Qril Percent 
0 30 0. 873 5 8. 749 9 30 16. 734 18 32. 492 
1 1. 746 5 30 9. 629 10 17. 633 19 34. 433 
1 30 2. 619 6 10. 510 11 19. 438 20 36. 397 
PD, 3. 492 6 30 11. 394 12 21. 256 22 30 41. 421 
2 30 4. 366 7 12. 278 13 23. 087 25 46. 631 
3 5. 241 7 30 13. 165 14 24. 933 30 57. 735 
3 30 6. 116 8 14. 054 15 26. 795 35 70. 021 
4 6. 993 8 30 14. 945 16 28. 675 40 83. 910 
4 30 7. 870 ) 15. 838 17 30. 573 45 100. 0 
TABLE 22.—Raitos for customary map scales 
Inches per} Miles per | Feet per | Meters per| Feet per 
Seale 1 to mile inch inch inch 165 inch 
600 105. 6 0. 00947 50 15.2 2 
1, 200 52.8 . 01894 100 30.5 4 
2, 500 25. 344 . 03946 208 63. 5 8.3 
4, 800 13. 2 . 07576 400 121.9 16 
5, 280 2, . 08333 440 134. 1 17.6 
10, 000 6. 336 . 15783 833 254. 0 33.3 
12, 000 5. 28 . 18939 1, 000 304. 8 40 
21, 120 3 . 83333 1, 760 536. 4 70. 4 
31, 680 2 «fi 2, 640 804. 7 105. 6 
45, 000 1. 4C8 . 71023 3, 750 1, 143. 0 150 
62, 500 1.014 . 98643 5, 208 1, 587. 5 208. 3 
63, 360 1 1 5, 280 1, 609. 3 211. 2 
90, 000 . 104 1. 4205 7, 500 2, 286. 0 300 
96, 000 . 66 1. 5152 8, 000 2, 438. 4 320 
125, 000 . 507 1. 9729 10, 417 3, 175.0 416.7 
500, 000 . 127 7. 8914 41, 667 12, 700. 0 1, 666. 7 
1, 000, 000 . 063 15. 7828 83, 333 25, 400. 1 SAOSONO 
2, 500, 000 . 025 39. 4571 208, 333 63, 500. 1 8, 333. 3 
TABLE 23.—Scale of velocity equivalents of the Beaufort scale of wind 
Beau Velocity 
wei Description Indicators of velocity 
4G Meters per Miles per 
; second hour 
Os Calimesa Calm air; smoke rises vertically..___-_-_| Less than 0.3.___| Less than 1. 
S| Mvioht ain ea ee Direction of wind shown by smoke drift, | 0.3 to 1.5___-_____| 1 to 3. 
but not by wind vanes. 
2 | Slight breeze__________ Wind felt on face; leaves rustle; ordinary | 1.6 to 3.3_______- 4 to 7. 
vane moved by wind. 
3 | Gentle breeze_________ Leaves and small twigs in constant mo- | 3.4 to 5.4________ 8 to 12. 
tion; wind extends light flag. 
4 | Moderate breeze - __-_-_- Raises dust and loose paper; small | 5.5 to 7.9_______- 13 to 18. 
branches are moved. 
5 | Fresh breeze _________- Small trees in leaf sway; crested wavelets | 8.0 to 10.7_______] 19 to 24. 
form on inland waters. 
6 | Strong breeze_________ Large branches in motion; whistling | 10.8 to 13.8______] 25 to 31. 
heard in telegraph wires; umbrellas 
used with difficulty. 
7 | High wind___________- Whole trees in motion; inconvenience felt | 13.9 to 17.1______] 32 to 38. 
when walking against wind. 
SMliGalett bt Ve-5 AE tS Breaks twigs off trees; wind generally | 17.2 to 20.7______| 39 to 46. 
impedes progress. 
9 | Strong gale____________ Slight structural damage occurs to signs; | 20.8 to 24.4______] 47 to 54. 
branches broken. 
10 | Whole gale___________- Trees uprooted or broken; considerable | 24.5 to 28.4______} 55 to 63. 
structural damage occurs. 
Me STORM eke ose ee Very rarely experienced; accompanied | 28.5 to 33.5______| 64 to 75. 
by widespread damage; forests wind- 
c thrown or broken off. 
12a Me Utes Cama Ceres ee oe lle eee el yee ee OR OA Pe ore eee 33.6 or above___-| Above 75. 
