1884.] 



on tlte Distances of the Fixed Stars. 



101 



So far as all existing researches go, a Centauri is the nearest of 

 the fixed stnrs. Regarding the faint comparison stars as practically 

 infinitely distant, let us try to realise how near or how far distant 

 a Centauri really is. 



If we wish to deal with distance so immense, we must alopt a 

 more convenient unit of measure. 



The most convenient unit for our purpose is the number of 

 years that light would take to reach us. Light takes almost exactly 

 500 seconds of time to come from the sun; this is a figure easy 

 to remember, and is probably exact to a single unit. The sun is 

 93 millions of miles distant, and this figure I believe to be exact 

 within 200,000 miles. 



Quite recently the accuracy of these figures has been confirmed in 

 a very remarkable way by different kinds of investigations by 

 different observers ; otherwise I should not have quoted them with so 

 much confidence. 



The parallax of a Centauri is three-quarters of a second of arc ; 

 therefore its distance is 275,000 times the distance of the earth from 

 the sun, and therefore light, which travels to the earth from the sun 

 in 500 seconds (i. e. in 8^ minutes) would take 4*36, or a little more 

 than 4^- years to come from a Centauri. 



You will find in the accompanying table a specific account of the 

 other results which were arrived at by Dr. Elkin and myself by 

 precisely similar means, and you will find on the wall diagrams 

 representing my own detailed observations in the case of Sirius and 

 c Indi. (See Diagrams IV. and V.; 



Table II. — Kesults of Recent Researches on the Parallax of Stars 

 IN the Southern Hemisphere. 



Time does not permit me to go into more detail as to each of 

 these separate results, full of interest though they are, and each of 

 them representing months of labour. 



