430 APPENDIX F. 



Forces and other Phenomena. — 11. The norther usually commences 

 with a violence nearly equal to its greatest force, if its initial point be 

 near the observer. If it has traveled some distance, it will be warmed 

 up, and moderated ia its violence, at first attack. Its greatest force 

 might be marked five, in a scale between a gentle breeze, at one, and a 

 hurricane, at ten. The writer has measured one traveling at about 

 thirty-two miles per hour — but many others at twelve to eighteen miles. 

 The mean progress seems to be about fifteen miles per hour. 



12. Just before a norther, two to six hours, the south wind lulls, and 

 the still air becomes very oppressive. A low black cloud rolls up from 

 the north, and when it comes near the zenith, the wind strikes with 

 vigor. Sometimes we have a sudden dash of rain; but generally 

 northers are intensely dry, and soon drink up all the moisture of the 

 surface earth, and of the objects upon it, capable of yielding their 

 humidity. 



Great thirst of man, and all other animals, is experienced ; an itching 

 sensation over the skin ; a highly electric condition of the skiu of horses 

 and cats ; a wilting and witheiing of vegetation, even when the tempe- 

 rature would not account for it ; a reduction of temperature, usually very 

 sudden, sometimes, though rarely, a degree per minute, for twenty 

 minutes ; and in winter commonly a reduction from 70" or 75°, to 30° 

 or 40°. 



This fall of temperature is the more severely felt fi-om the diying 

 power of the north wind — evaporation fi:om the surface of the skin 

 increasing the severity of the temperature. 



13. Nervous, rheumatic, and gouty persons suffer more severely than 

 others. To invalids suffering from other maladies, it has not been found 

 unhealthy ; and for persons of weak lungs, if not too much exposed to 

 its direct fury, it is found, to be more salubrious than the humid south 

 vrinds. Gonsmmptions do Twi oriyinate over the area of the nortjier. 

 On the contrary, many persons afflicted with weak or diseased lungs, 

 resort to this region, and find relief. The western and northern portions 

 of this area are most salubrious, and best adapted to weak lungs. 



Phenomena not readily explicaMe. — When a dry norther commences, 

 the whole air, in an hour or two, curdles, and becomes smoky, or rather 

 whitish, and has a distinct smell. Its odor sometimes resembles that 

 which is developed by a flash of lightning, though, at other times, it 

 reminds one of fine straw smoke, in its odor. 



It is highly probable that this turbidness and odor, are flue to the 

 ozone set free, by the high electrical excitation, in a dry r jther. Ex- 

 periments instituted to test the matter, last April, werp loo late in the 

 season. 



Sirocco. — When the norther has a little westmg, it is observed to 

 be more intensely dry, and to be destructive to vegetation, even before 

 the frost which usually follows it. Com, beans, young foliage, and the 

 grass and weeds of the prairie, bow and wither before it.* A few of 

 these I have called Siroccos. They occur as well in summer as in spring 

 or autumn, and differ, in several respects, from the true norther. 



* The citizens of Galveston, and the southern portions of Texas, ■will remember 

 the violent north-wester in 1856, which preceded and attended the storm which 

 wreclced the Nautilns. It was, in my judgment^ a true Sirocco. In lilie manner the 

 noith-west wind, that withered the corn-nelds m Lamar, Fannin, and Grayson, and 

 the counties south of these, on the 17th day of August, 1858, deserves a like name. 



