COMMON THINGS THE ALMANACK. 



the end, that is, sunrise, midday or noon, and sunset. The first 

 and last of these having been fully explained, it remains to offer 

 some observations on the second. 



The hour of noon, or midday as commonly understood, is that 

 at which a correctly regulated clock strikes twelve, or the moment 

 at which the centre of the sun's disc passes the meridian, or the 

 moment which divides the interval between sunrise and sunset into 

 two equal parts. When these conditions come to be closely 

 examined, however, they are found to be inconsistent one 

 with another, the times which they severally express being in 

 fact different. 



63. It has been already explained in our Tract on "Time," 

 that the moment at which the centre of the sun's disc passes the 

 meridian is not that at which a correctly going clock strikes 12. 

 The former is apparent, and the latter mean or civil noon. It is to 

 the latter that the term noon or midday is commonly applied r and 

 to which we shall here exclusively apply it. 



Since, therefore, the moment at which the centre of the sun's 

 disc each day passes the meridian is not the moment of noon, nor 

 any fixed and invariable time either before or after noon, it is as 

 necessary that the almanack should indicate from day to day what 

 this time is, as that it should show the times of sunrise and sunset. 

 In all good almanacks, a column is therefore appropriated to this, 

 placed as it ought naturally to be between those which indicate 

 sunrise and sunset. This column is variously headed, " equation 

 of time," or " sun fast," or " sun slow," or " clock before sun," 

 or " clock after sun," as the case may be. Whatever be the 

 words at the head of the column, the numbers which are consigned 

 to it are the number of minutes and seconds before or after 

 twelve by the clock (supposed of course to be perfectly correct and 

 to show civil or mean time *) at which the centre of the sun's disc 

 passes the meridian. 



This meridional transit of the sun's centre may vary froni the 

 hour of noon to the extent of more than sixteen minutes one way 

 or the other. 



If the almanack for 1854 be referred to, it will be seen that the 

 meridional transit of the sun's centre took place in that year 



From 1st Jan. to 15th April . . .in the afternoon. 



,, 16th April to 14th June . . . in the forenoon. 

 ,, 15th June to 31st Aug. . . in the afternoon. 



,, 1st Sept. to 25th Dec. . . . in the forenoon. 

 25th Dec. to 31st Dec. . . . in the afternoon. 



The meridional transit of the sun's centre took place at the 



* See Tract on " Time " (36). 

 34 



