J REMARKS UPON METEOROLOGY. 



in a point in the horizon; sometimes the lines converge ot 

 both ends, in opposite parts of the horizon, while at other 

 times the lines shoot up to the zenith and terminate there. 

 Upon the shape, extent, and position of these arcs, and 

 upon their relation to the wind and the barometer, many 

 meteorological predictions depend. In the fits* place :is to 

 their shape, they may be composed of long parallel lines or 

 threads, forming a lunar arc; or of small rounded clouds, 

 lying side by side or in rows, a mottled arc; or they may he 

 composed of clouds resembling a volume of smoke, as it 

 rises from a chimney top, a wreathed arc; or they may as- 

 sume the appearance of feathers, having h linear centre and 

 lateral branches, a feathered arc. Then independent of any 

 particular shape, the arc may be perfectly or imperfectly 

 formed; it may reach only to the zenith, or it may reach 

 quite across to the opposite point ; it may be either increas- 

 ing or diminishing in size, forming a precipitating or dis- 

 solving arc ; or, according as it coincides with the present, 

 future, or past state of the wind, it will take the title of a 

 Indications of present, future, or past arc. A present arc almost always 

 it e W1 Jf indicates, that the wind will leave the point from which it is 

 blowing; and when it arises from a S or W quarter, we 

 may form a pretty good judgment whether the wind v.- ill go 

 to the right or left b:\nd, by noticing whether the barome- 

 ter be rising or falling; if rising, the wind will pass to the 

 right hind, if falling, to the left ; in employing the terms 

 right and left, I suppose the face of the obvet ver turned to 

 the point of the horizon from which the arc proceeds. The 

 appearance that was observed on this day was a future arc, 

 and according to a pretty general rule, that whenever an 

 arc is formed to the left hand of the wind, and the barome- 

 ter at the same time falls, the wind will move into that 

 point, we had in the evening a squall from E. On the 4th 

 •was another arc, which passed from S to N ; an expression 

 which signifies, that it had two converging points in oppo- 

 site parts of the horizon, and that it was most distinct in 

 the S end: had it been equally perfect at both extremities, 

 it would have been expressed, an arc between N and S. As 

 the wind and the arc crossed each other at right angles, the 

 direction of the arc did not inform us, whether the wind 



would 



