250 ANNUAL REPORT SMITHSONIAN INSTITUTION, 1911. 
The conference at Washington also recommended the adoption of a 
dial of 24 hours, which has the advantage that the use of the abbre- 
viations a. m. and p. m. is unnecessary, as is the case with a dial of 
12 hours. Unfortunately the spread of this reform seems to have 
nearly stopped. It is officially used at present only in Belgium, 
Canada, Spain, France, Italy, and British India. 
- The civil day commences at mean midnight. For astronomical 
purposes a system of 24 hours is universally employed but the zero 
hour corresponds to mean noon, so that mean astronomical time is 
exactly 12 hours later than mean civil time. This convention was 
adopted so that the same date could be used for all the observations 
of a single night. Although the conference at Washington resolved 
that as soon as practicable all astronomical and nautical dates over 
the whole world should commence at mean midnight, astronomers 
have not so done. English mariners indicate by p. m. the afternoon 
hours and by a. m. those of the forenoon. 
The time corresponding to certain zones have received special 
designations: 
Western European time, or western time, corresponding to the zone of Greenwich. 
Central European time, or central time, corresponding to the zone 1 hour east 
of Greenwich. 
Eastern European time, or eastern time, corresponding to the zone 2 hours east of 
Greenwich. 
Eastern standard time, corresponding to 5 hours west of Greenwich. 
Central standard time, corresponding to 6 hours west of Greenwich. 
Mountain standard time, corresponding to 7 hours west of Greenwich. 
Pacific standard time, corresponding to 8 hours west of Greenwich. 
Since 1884 many countries have adopted systems of time based 
upon the zones and the meridian of Greenwich. In the following 
table are given the principal nations or portions of nations, the merid- 
ians adopted, and the differences between their standard times and 
that of Greenwich. The plus sign (+) indicates that the given 
difference must be added to Greenwich time in order to obtain the 
time in a given country; the negative sign (—), that it must be 
subtracted. 
The systems of time in various countries. 
Region or country. Meridian, Difierence. Remarks. 
Africa: 
Hnglish:southees sso ee ERG Greenwich. ....--- J 2) els 
Germanisouths) Peeseags tereeet ey s5 tale ee Ores: Sas hs HF ESO 10 
SPOriuUeuese Westies en ae Sa GOs ee ate ea): Legal time. 
IPOrUUIPTIESOCASbans ac seen ee lace Peres Osan eee eae estan tO) Do. 
Argentine Republic:... 22. -.-.+-) 2. ese Cordobai. 4.2.2. —4 16 48.2 | Official time. 
Australia; 
Central..:.. Be a ara aici aot al Greenwich.......- +9 30 O 
IWIOSLELMe Saou ciesie sic seis sltinacemiacaie Dee lenaen 6 fo eee +8 0 0 
