Intelligence and Miscellanies. 361 



levolve swiftly, there will appear to be a continued circle of 

 light. If the circle be increased in size, or if the ignited end 

 be made to revolve more slowly, the circle may be made to 

 appear much brighter on one side than on the other, or it 

 may appear bright on one side and entirely broken on the 

 other. The twinkling of the stars and the deception in the 

 number of stars visible to the naked eye on a clear evening, 

 is somewhat similar to this. A fixed star having no visible 

 diameter, only one stream of the rays of light that proceed 

 from it can enter the eye ; and since the fixed stars are at 

 such an immense distance, the particles of light from one of 

 them that would fall upon so small a surface as the pupil of 

 the eye, must be at a considerable distance from each other. 

 When therefore a particle of light from a fixed star falls upon 

 the eye, it produces a vivid impression : this impression be- 

 comes gradually dimmer, until another particle arrives, pro- 

 ducing a vivid impression again. This causes the twinkling. 

 Here the circle is unbroken — another particle arrives, before 

 the impression made by the former one has entirely vanish- 

 ed. But the particles of light which proceed from more dis- 

 tant stars, fall upon the eye at too great intervals to keep up 

 a continued image. Hence when a particle of light from 

 one of these stars falls upon the eye, it produces a percep- 

 tion of a star ; but when we endeavour to contemplate this 

 star, it is invisible, because the image formed has vanished, 

 and another particle has not yet arrived to renew it. In this 

 way we are led to suppose there are more stars visible, than 

 upon examination we find. 



The only cause why telescopes enable us to see stars that 

 are invisible to the naked eye, is, that they concentrate the 

 rays from so large a surface, as to keep up a continued image 

 of the star. 



4. On the cause of hail during warm weather; hy Ben- 

 jamin Hallowell. — Large hail frequently falls during very 

 warm weather, which we have had repeated instances of, 

 the past summer. This phenomenon occurs only when 

 there is an excessive accumulation of electricity in the at- 

 mosphere, and it may be accounted for in the following 

 manner. Two highly charged clouds in opposite electric 

 states, coming within the electric influence of each other, 

 displace the air from between them so as to form a passage' 

 for the electric fluid, while the moisture remains. This sud- 



Vol. XV.— No. 2. 21 



