+---------------------------------+---------+----------------------+ | VELOCITY. |Pressure | | | | on a |Character of the Wind.| +---------+-----------+-----------+Sq. Foot.| | |Per Hour.|Per Minute.|Per Second.| | | +---------+-----------+-----------+---------+----------------------+ | Miles. | Feet. | Feet. | Lbs. | | | 1 | 88 | 1·5 | ·003 | Barely observable. | | 2 | 176 | 2·9 | ·012 |} Just | | 3 | 264 | 4·4 | ·027 |} perceptible. | | 4 | 352 | 5·9 | ·048 | Light breeze. | | 5 | 440 | 7·3 | ·075 |} Gentle, | | 6 | 528 | 8·8 | ·108 |} pleasant | | 8 | 704 | 11·7 | ·192 |} wind. | | 10 | 880 | 14·7 | ·3 | Fresh breeze. | | 15 | 1,320 | 22 | ·675 | Brisk breeze. | | 20 | 1,760 | 29·4 | 1·2 | Stiff breeze. | | 25 | 2,200 | 36·7 | 1·875 | Very brisk breeze. | | 30 | 2,640 | 44 | 2·7 |} High | | 35 | 3,080 | 51·3 | 3·675 |} wind. | | 40 | 3,520 | 58·7 | 4·8 | Very high wind. | | 45 | 3,960 | 66 | 6·075 | Gale. | | 50 | 4,400 | 73·4 | 7·5 | Storm. | | 60 | 5,280 | 88 | 10·8 |} Great | | 70 | 6,160 | 102·7 | 14·7 |} storm. | | 80 | 7,040 | 117·2 | 19·2 | Hurricane. | | 90 | 7,920 | 132 | 24·3 |} | | 100 | 8,800 | 146·7 | 30 |} Tornado. | | 110 | 9,680 | 161·2 | 36·3 | } | | 120 | 10,560 | 176 | 43·2 | } “Washoe | | 130 | 11,440 | 191 | 50·7 | } zephyrs.”[2] | | 140 | 12,320 | 205·3 | 58·8 | } | | 150 | 13,200 | 220 | 67·5 | } | +---------+-----------+-----------+---------+----------------------+ [2] With apologies to Mark Twain. [Illustration: Fig. 72_a_.--Angles and degrees compared. It will be observed that an angle of 1 in 4 is practically 14°.] TABLE OF EQUIVALENT INCLINATIONS.