234 On the Appearance of the Stars when viewed Cursorily. 



Art. VIII. — An Attempt to account for the fact that the Stars 

 appear greater in number when viewed cursorily than 

 when examined with attention.* By a Correspondent. 



The discoveries of science are well known to be frequently 

 accidental, and the observations of one literary man will of- 

 ten prove useful and applicable to the pursuits of another, 

 even in a different branch of study. It is the adoption and 

 generalization of such a discovery that constitutes the aim of 

 these remarks. 



I have long been dissatisfied with the explanation currently 

 given of the apparent number of the stars being greater to a 

 cursory observer, than when attentively examined. Fergu- 

 son says, (Astronomy, chap, xx.) " The number of the stars 

 discoverable by the naked eye in either hemisphere is not 

 above a thousand. This at first may appear incredible, be- 

 cause they seem to be without number ; but the deception 

 arises from our looking confusedly at them without reducing 

 them to any order ; for, look but steadfastly on a pretty large 

 portion of the sky, and count the number of stars in it, and 

 you will be surprised to find them so few. 1 ' 



The method by which I account for the circumstance is as 

 follows : Messrs Herschel and South, (Edinburgh Journal of 

 Science, vol. ii. p. 28, &c. Also Phil. Trans, and Mem. Ast. 

 Soc. Lond.) giving an account of their observations on double 

 stars, remark, " A rather singular method of obtaining a view, 

 and even a rough measure of the angles of stars of the last de- 

 gree of faintness has often been resorted to, viz. to direct the 

 eye to another part of the field ; in this way, a faint star in the 

 neighbourhood of a large one has often become very conspi- 

 cuous, so as to bear a certain illumination, which will yet to- 

 tally disappear, as if suddenly blotted out, when the eye is 

 turned full upon it, and so on, appearing and disappearing al- 

 ternately as often as you please. 11 



I may illustrate this by an observation of my own, made 

 some months since, with a 8g feet achromatic by Carey, and 

 2.750 inches clear aperture, using a low power which I have 



* We should be glad to hear again from the author of this article, and, 

 if agreeable, to learn his address. — En. 



