2 ASTRONOMY. 



Gravity possibly not instantaneous. 



It has been observed that most of the agents we 

 are acquainted with require time to pass from one 

 point of space to another ; the force of gravity may 

 also be of this nature, and may not, any more than 

 light, be instantaneously transmitted from the sun to 

 the planets, or from the planets to one another. 



Is attraction a virtue propagated in time or not ; 

 and if so, does it travel quicker or slower than light ? 



The Solar Spots. 



Sir William Herschel attributes the spots on the 

 sun to the emission of an aeriform fluid, not yet in 

 combustion, which displaces the great luminous at- 

 mosphere, and which is afterwards itself to serve the 

 purpose of supporting combustion. Hence he sup- 

 posed the appearance of copious spots to be indica- 

 tive of the approach of warm seasons on the surface 

 of the earth, and he has attempted to maintain his 

 opinion by historical evidence. 



Light. 



At the depth of 723 feet through sea water, ac- 

 cording to Bouguer, light ceases to be transmitted, 

 and probably at three times that depth there is per- 

 petual darkness. 



Only one hundred thousandth's part (-YO^-OWU) f 

 the vertical rays of the sun can penetrate below 47 

 fathoms ; the depths of the ocean are consequently 

 involved in perpetual darkness. 



The most remarkable property of light is its 

 velocity. 



A peculiar Light. 



Moses says that the light was first formed and that 

 was the first day. On the third day after this, the 



