526

360° O' 27".45S65.25

= 59' 8".SS,

,m 5(?.555solar

is the increase of the Sun’s mean longitude in one day,sisting of twenty-four mean solar hours. A mean solar a ;'therefore, must exceed a sidereal day, by the portion of 81time consumed in describing 59' 8".33. Now 360° arescribed in twenty-four sidereal hours;

aq / of* 33

360° : 24 h :: 59' 8".3S : 24 x

360

= 236 s .555 = 3 m 56 s .555 of sidereal time:

hence, twenty-four mean solar hours are equal to 24 1 ' 3 1of sidereal time : and a clock will be adjusted to meantime, if its index hand makes a circuit, whilst that of the siderclock makes one circuit and S m 56 s .555 over: or, if e ac ^ c ..beats seconds, the solar clock ought to beat. 86400 times ' v 1the sidereal beats 86636 -j, nearly.

In order to find the number of solar hours to which a sid ereday of twenty-four hours is equal, we must use this proporti° n ’

86636.555 : 24 :: 86400 : 24 x 86400

86636.555

= 2S h . 93447 = 2S h 56“ 4’.092 of mean solar time.

The difference between twenty-four hours and the last time* ^3“ 55 s .908. Hence, subtract from twenty-four hours of sidere ^time 3 m 55’.908, and the remainder is the number of mean s °' *hours, minutes, seconds, and decimals of seconds, to which twefour hours of sidereal time are equal. 1 l '--

andad

Hence, subtract 1™ 57 s .954 from twelve sidereal hours,

the remainder is their value in mean solar time; sU k*f*j r0“ 58’.977 from six sidereal hours, and the remainder isvalue in mean solar hours: and these subtracted quantitiescalled the accelerations of the stars in mean solar time; aof which accelerations might, as it is plain from what precebe easily formed (see Zach’s Table XXVI, in his Non*’ 8Tables d’Aberration, &c.)