PROCEEDINGS 



OK THE 



Delaware County Institute of Science 



Vol. Ill, No. i Octohkr, 1907 



THK STAR VAULT AND THE MOVING OBSERVER. 



BY JACOI! H. BROWN.* 



I have in miud to describe in this paper certain appear- 

 ances on the star vault which ensue upon certain changes in 

 the position of the observer ; and, as many of the circum- 

 stances conceived to exist are wholly imaginary, and as some 

 of the positions supposed to be assumed are entirely beyond 

 the limit which it is at present possible to attain, I shall have 

 nothing but the just inferences of science to bear me out in 

 my various statements. 



In order, therefore, to insure greater accuracy of concep- 

 tion I ma3^ perhaps, be allowed to remind 3'ou that astrono- 

 mers have the v/s/b/c /lon'rjon , whose plane passes perpendicular 

 to the earth's railius through the e^-e of the observer, and the 

 rational horirjoi , whose plane passes parallel to this through 

 the centre of the earth. This latter need not concern us, the 

 distance measured on a perpendicular between the two being 

 a question of high science. When, therefore, the horizon is 

 spoken of it is the visible horizon that is meant, and this is, 

 as far as our intents and purposes extend, identical with the 

 rational horizon : as will, indeed, appear clear when it is 



a. remembered that the distance between the two is the length of 

 c: 



ID". 



' * Through the kindness of Miss Anne Knapp Whitney, the Institute 



^^ is enabled to publish this article fro.n the pen of its deceased member, 

 Jacob H. P)ro\vn. 



BOTANIC 



