1886.1 Mr. W. H, M. Christie on Universal Time. 387 



WEEKLY EVENING MEETING 



Friday, March 19, 1886. 



Sir William Bowman, Bart. LL.D. F.K.S. Manager and Vice- 

 President, in the Chair. 



W. H. M. Christie, Esq. M.A. F.E.S. Astronomer Royal. 



Universal Time. 



Considering the natural conservatism of mankind in the matter of 

 time-reckoning it may seem rather a bold thing to propose such a 

 radical change as is involved in the title of my discourse. But in 

 the course of the hour allotted to me this evening, I hope to bring 

 forward some arguments which may serve to show that the proposal 

 is not by any means so revolutionary as might be imagined at the 

 first blush. 



A great change in the habits of the civilised world has taken place 

 since the old days when the most rapid means of conveyance from 

 place to place was the stage-coach, and minutes were of little im- 

 portance. Each town or village then naturally kept its own time, 

 which was regulated by the position of the sun in the sky. Sufficient 

 accuracy for the ordinary purposes of village life could bo obtained 

 by means of the rather rude sun-dials which are still to be seen on 

 country churches, and which served to keep the village clock in 

 tolerable agreement with the sun. So long as the members of a 

 community can be considered as stationary, the sun would naturally 

 regulate, though in a rather imperfect way, the hours of labour and 

 of sleep and the times for meals, which constitute the most important 

 epochs in village life. But the sun does not really hold a very 

 despotic sway over ordinary life, and his own movements are 

 characterised by sundry irregularities to which a v/ell-ordered clock 

 refuses to conform. 



Without entering into detailed explanation of the so-called '* Equa- 

 tion of Time," it will be sufficient here to state that, through the 

 varying velocity of the earth in her orbit, and the inclination of that 

 orbit to the ecliptic, the time of apparent noon as indicated by the 

 sun is at certain times of the year fast and at other times slow, as 

 compared with 12 o'clock, or noon by the clock. [The clock is sup- 

 posed to be an ideally perfect clock going uniformly throughout the 

 year, the uniformity of its rate being tested by reference to the fixed 

 stars.] In other words, the solar day, or the interval from one noon 

 to the next by the sun, is at certain seasons of the year shorter than 

 the average, and at others longer, and thus it comes about that by 

 the accumulation of this error of going, tlie sun is at the beginning 



