40 Messrs Herschel and South oil the Double Stars 



the air above 32° (the freezing point.) For this reason the 

 air of England is ^4° pr 25° more heated than that of the be- 

 fore-mentioned countries. The air of Sweden and Norway 

 will then of course, by the laws of comparative specific gravi- 

 ties, displace that of England, and from the relative situation 

 of those countries with this country will produce a north- 

 east wind. This current is in common stronger by day than 

 by night, because the variation of temperature in the air of 

 Great Britain is at that time the greatest, being frequently 

 from 50° to 60° about noon, and sinking to 32° in the night. 

 I do not submit this hypothesis as capable of determining 

 the exact duration, or the existence of this current of the air 

 during the whole of the period I have mentioned, but think 

 it highly probable that it will account for a north-east wind 

 prevailing at this particular season, as observations prove that 

 it does. 



Art. VII. — On the Systems of Double Stars which are 

 S7ipposed to be Binary 07ies, from the observations of Sir W. 

 Herschel, and Messrs Herschel aiid South. 



In a preceding Number we have given an account of sixteen 

 systems of double stars which have been demonstrated to be 

 binary ones, from the observations of Sir W. Herschel, and 

 Messrs Herschel and South. We proceed now to those sys- 

 tems which will probably turn out to be binary, from the ob- 

 servations of the same astronomers. 



1. 65 Piscium, R. Asc. 0'' 40'. Decl. N. 26° 43\ 

 This star is a double one, and is a very pretty object, both 

 stars being of the seventh magnitude. The angle of position in 

 1783.15 was 30°. 95, n p or sf. In 1822.86 it was 25°.80. 

 The rate of decrease, from these and other observations, is 

 0°.l 17 per annum ; and if we suppose it to revolve uniformly 

 in a circle, its period would be 3077 years. The distance in 

 1783 was IJ, the diameter of the large star. In 1819 M. 

 Struve made it 5". 77. The distance seems like the angle to be 

 subject to a slow variation. 



