TIME-BECKONING. 



113 



The sidereal day fulfils these conditions, and therefore suggests 

 itself as being suited for the standard required. 



The sidereal day is not, however, sufficiently marked for the ordi- 

 nary purposes of life. The generality of mankind could not easily 

 note the culmination of a star. On the other hand, the diurnal 

 return of the sun in the heavens is a more striking and easier 

 observed phenomenon. Accordingly, there is everything to suggest 

 the adoption for the unit measure, not the solar day on account of 

 its variable length, but the mean period occupied by a revolution of 

 the earth on its axis, in relation to the sun. 



That period would be precisely equal in length to the artificial 

 day, known as the mean solar day. The unit measure proposed 

 should not, however, be considered in the light of an ordinary day, 

 but rather as a known period of abstract time — " day " being the 

 name given to denote certain local phenomena successively and 

 continuously occurring at the earth's surface. 



It is proposed to divide the unit measure into twenty-four equal 

 parts, and these again into minutes and seconds, by a standard time- 

 keeper or chronometer, hypothetically stationed at the centre of the 

 globe. 



Fio. 1. 



It is proposed that, in relation to the whole globe, the dial plate 

 of the central chronometer shall be a fixture, as in Fig. 1 ; that each 



