ASTRONOMICAL NOTES FOR OCTOBER, 1881. 359 



ASTRONOMY. 



ASTRONOMICAL NOTES FOR OCTOBER, 1881. 



BY W. W. ALEXANDER, KANSAS CITY, MO. 



Sidereal time of mean noon on the ist i2h. 42m. 27.49s; on the 31st i4h. 

 40m. 44.09s. Equation of time for apparent noon, ist lom. 30s; 31st i6m. i8s 

 Equation of time is used to avoid the irregularity which would arise from using 

 the true sun as the measure of time, a fictitious sun, called a Aiean Sun, is sup- 

 posed to move in the equator with a uniform velocity. This mean sun is sup- 

 posed to keep, on the average, as near the real sun as is consistent with perfect 

 uniformity of motion ; it is sometimes in advance of it, and sometimes behind it, 

 the greatest deviation being i6m. i8s. 



The most favorable time for making telescopic observations will be from the 

 1 2th to the 1 6th and from the 27th to the end of the month. It reaches perigee 

 on the 4th, apogee on the i6th and returns to perigee on the 31st. 



