Astronomical and Nautical Collections. 365 



If we take the mean of the fourteen results as relating generally 

 to stars from the 1st to the 4th magnitude, it will appear that the 

 mean sum of the parallaxes of two opposite stars is equal to 

 0".036 of space, or the parallax of a single star equal to 0".018. 



If any reliance can be placed on these observations, every 

 attempt to determine the parallax of these stars in declination 

 must be entirely hopeless ; since in this case we can only measure 

 the shorter axis of the Ellipse, and the uncertainty of refraction 

 must amount, at least, to twenty times the quantity we are in 

 search of. 



v. An account of some Parhelia seen at the Cape of Good Hope. 

 By the Rev. Fearon Fallows, A. M. 



June 21, 1823, 

 My dear Sir, Cape Town. 



If you think the following worthy of insertion in any Scientific 

 Journal, it is at the Editor's service. 



I am, my dear Sir, 

 To Dr. T. Young, Yours most truly, 



&c. &c. &c. F. Fallows. 



Wednesday Evening, May 7, 1823. — During my ride this evening 

 toward Sea-point, I was favoured with a most beautiful sight at 

 sunset. The sky was delightfully clear ; — not a cloud was visi- 

 ble, and the sea horizon remarkably distinct. When the sun's 

 lower limb had just dipped the water-edge, immediately several 

 parhelia made their appearance, — four on the left hand, and three 

 on the right. They assumed the same shape as the real sun, and 

 were as bright, but not so large. When the upper limb of the sun 

 came in contact with the horizon, it, and the mock suns, appeared 

 as bright points upon the water edge, and then, in an instant, all 

 vanished together. Upon my return home, I made a diagram of 

 this phenomenon, as seen at short intervals after each other, a 

 copy of which (in preference to a minute -description,) I beg here 

 to subjoin. 



H R the horizon, S the real sun. The remaining figures upon 

 H R are the mock suns. Bar. 30.2 inches. Ther. 04 inches. 



