136 



TRANSACTIONS OF THE CANADIAN INSTITUTE. 



[Vol. II. 



second hour meridian ; at the end of the third hour it will be on the 

 third hour meridian, and so passing over the whole twenty-four.* 



This mode of distinguishing the hour meridian, possesses peculiar 

 advantages which will be made plain on reference to the diagram, show- 

 ing a projection of the northern hemisphere. The figures around the 

 circumference indicate the new meridians numbered as described. The 

 same figures indicate the twenty-four hours into which the world's stand- 

 ard unit measure of time is divided. The motion of the earth on its 

 axis brings each hour meridian in succession to its solar passage, and a 

 complete coincidence is obtained between the hour meridians and the 

 hours of the world's standard. For example, w^hen the solar passage is 

 on hour meridian number 12, it will be 12 o'clock ; when on hour meri- 

 dian number 17, it will be 17 o'clock, and so on for every meridian. 

 Throughout each day the solar passage becomes the index of time com- 

 mon to the world. 



* The time nomenclature committee of the Royal Society of Canada has had under consider- 

 ation the best mode of distinguishing the hour meridians. This committee reported, May 29th 

 1891, in favour of using numbers in preference to geographical or other terms, so as to obviate all 

 confusion, numbers having the same precise meaning in all languages and being equally 

 appropriate in both hemispheres. The committee likewise expressed the opinion, which was 

 unanimously endorsed by the society, that the hour meridians should be numbered in consecutive 

 order from the anti-prime meridian as zero, following the apparent motion of the sun towards the 

 west, that is to say as follows, viz : 



Anti-Prime Meridian 180° East and West Longitude 



Hour Meridian 165° East Longitude, numbered 



150" 



135° 



120° " " 



105° 

 90° " «' 



75° 

 60° 

 45° 



15 

 " 0° Prime Meridian " 



" 15° West Longitude " 



30° 



45» 

 60° 



75° 



90° 



105° 



" 120" 



135° 

 " 150° 



165° 

 Anti-Prime Meridian 180° East and West Longitude 



