♦ KNOWLEDGE . 



NIGHT SKY FOR SEPTEMBER (Fii 



Showing the heavens as they appear at the following hours :- 

 September 1 at lOi o'clock. | Septembt r 9 at 9J o'clock. 



September 5 at 10 o'clock. 



September 13 at 9i o'clock. 



[jerfect its construction, is more liable to 

 at a fixed station. That it is contiim 

 shaken is something, but it is not the chii 

 it is exposed. Tlie n;reat chani^e.s of t ini| 

 when a shij) jiasses from the lrMi|M i iir 

 the torri<l zone to tlie tenipeiMi. 

 meter far more sevei-ely than ill! \ i 

 And then it i.s to be noted tli;it' ;i n > i_\ m 

 error corresponds to a differenee of liin_'i 

 eient to occasion a serious error in the ; 

 position. For this reason and for other 

 to have some means of determinini; C 

 independently of chronometers. 



This, in fact, is the famous jiroblein 



•rs offered and have been 

 yroblem that AVhiston. 

 Newton was afraid of 



s aiul iiiortaTS ; for which 



