NA TURE 



[Nov. 6, i Si 



scheme is, outside of the Conference, the first really scien- 

 tific step that has been taken in the practical unification 

 of time throughout the world. Whether the number of 

 meridians might be doubled is perhaps a question, but, 

 as it stands, the scheme is extremely simple. For since 

 the minutes and seconds counted in the several districts 

 are the same as the minutes and seconds of Greenwich or 

 universal time, the mere addition of another hour hand to 

 the clocks in common use, placed in the proper position and 

 travelling with the ordinary hour hand, would enable either 

 local standard time or universal time to be read off at 

 pleasure from the one clock. The ordinary hour and 

 minute hands might be black and the additional hour 

 hand of a lighter colour, in which way sufficient dis- 

 tinction would be produced. Such clocks should show 

 hours from oh. to 2ih. Or the conversion might be 

 made in other ways. Referring to the American division 

 before described, all entries might be distinguished as 

 " local standard time," and a precept added to indicate 

 that, to obtain universal time, 5, 6, 7, or 8 hours must 

 be added, as the case may be. Or denoting the times 

 as "standard times on the 5th meridian west," &c, 

 the variation from universal time is at once shown. 

 The reader will probably now have grasped the special 

 merit of this system, the readiness with which either 

 local time or universal time can be together indicated. 



It may be interesting to show how the American plan 

 of division into districts defined by hourly meridians 

 would work if applied generally to the countries of the 

 world. A scheme in regard to some of these countries is 

 herewith annexed. 



il ude from 

 Greenwich of Local time at 



Countries 'meridian to be which universal 



employed for local date changes 



Grenl Britain, France, and ) , 



Spam | oh - 



Norway, Sweden, Germany, 

 Austria, and Italy... 



Western Russia, Turkey. 

 and Egypt 



Western India 5I1. ,, ... 5I1. 



Eastern India ... , 6I1. ,, ... 6h. 



Western Australia Sh. ,, ,. Sh. 



South Australia 



Victoria, New South Wales, 

 and Queensland 



New Zealand 



California 



Eastern America ( Washing- 

 ton) 



In east longitude decrease, and in west longitude increase, the 

 local standard time by the hours of longitude to obtain universal 

 time. 



The scheme in fact resolves itself into adopting in any 

 country the time of the neirest integral hourly meridian. 

 Russia would become divided in some such way as 

 America. In each case the minutes and seconds of local 

 standard time would be similar to those of Greenwich or 

 universal time, change of the hour, according to the 

 precept given at the foot of the table, converting the local 

 standard time at once into universal time. We are quite 

 aware that a scheme of this kind can scarcely be expected 

 yet to take practical shape, but it seems well to point out 

 generally the direction in which with the least incon- 

 venience a satisfactory solution of the problem of counting 

 universal time in conjunction with local time may be 

 possible. 



The right hand column of the preceding table indicates, 

 in regard to the universal day proposed by the Conference, 

 the hour of the local civil 'day at which, in the several 

 districts, the universal date would change, the civil date 

 of course changing at midnight. It will be remarked that 

 in all countries in east longitude as far as Australia, the 



ih. east 



Midnight 

 ih. morning 



2h. 



change of universal date (following that of the same 

 civil date) takes place generally in the morning hours, 

 before the business hours of the civil day, the universal 

 and civil dates being then in accord until civil midnight. 

 In America the universal and civil dates are in accord 

 from civil midnight until towards the next evening when 

 the universal date changes (before change of the same 

 civil date). In all these cases the change of universal 

 date occurs at an hour well away from business hours. 

 Only in New Zealand would there be inconvenience, the 

 change of universal date occurring at civil noon, twelve 

 hours after change of the same civil date. Knowing 

 approximately the local time at which the universal date 

 changes, a clock fitted with an additional hour hand in the 

 way described would indicate at once the precise time of 

 change. 



The resolution of the Washington Conference further 

 expresses a hope that as soon as practicable astronomical 

 and nautical days may be arranged everywhere to begin 

 at mean midnight, which would simplify any desired con- 

 version into the proposed universal time. Passing by the 

 nautical aspect of the question we may remark, that astro- 

 nomers as a rule count their mean solar day of twenty- 

 four hours from noon, commencing twelve hours later 

 than the civil day of the same date, and the day is thus 

 understood in all published observations and astronomical 

 works. There is another consideration, somewhat fanciful 

 perhaps, that astronomical observations being taken 

 mostly at night it seems objectionable to make a change 

 of date at midnight in the middle of a series of observa- 

 tions ; but this carries now with it much less weight 

 since attention to solar phenomena has so increased 

 observation by day. It was perhaps felt at the Con- 

 ference that the lo :al civil and astronomii al days should 

 correspond as a matter of convenience in itself, and as 

 simplifying the relation of both with the proposed uni- 

 versal day, thus promoting the use of the latter as might 

 become convenient, either in civil or scientific affairs. To 

 effect such correspondence, one of the days had to be 

 altered, but since any proposition to change the local civil 

 date at noon could not be seriously entertained, it was 

 better that the astronomer should assimilate his day with 

 the civil day. Indeed it was formerly the practice in 

 France to employ the astronomical day, commencing at 

 midnight, in the construction of planetary and lunar 

 tables. 



The proposed change in the time of commencement of 

 the local astronomical day will involve some present 

 awkwardness from the circumstance that the different 

 astronomical ephemerides are calculated for astronomical 

 time as hitherto reckoned, in addition to which our own 

 Nautical Annan ic is prepared several years in advance. 

 Temporary inconvenience more or less there must be, but 

 the new reckoning, when fully established, will be found 

 to possess some distinct advantages. \- concerns the 

 Royal Observatory at Greenwich, the Astronomer-Royal 

 proposes to adopt the recommendation of the Washington 

 Conference by commencing on January 1 of next year to 

 count the astronomical day from the midnight preceding 

 the nominal civil date, thus bringing the Greenwich astro- 

 nomical day into correspondence with the Greenwich civil 

 day, which is the universal day of the Conference ; he 

 proposes further to alter the indication of the public clock 

 at the entrance gate of the Observatory, so that oh. of the 

 clock shall also commence with midnight : all being 

 counted from oh. to 24I1. The time reckoned within the 

 Observatory and that shown on its external wall will then 

 be in accord. So far the astronomer. If, in addition, 

 the civilian would relinquish the use of the confusing a.m. 

 and p.m., and instead count the hours also from oh. to 

 24b.., beginning with midnight, all parties would then be 

 using the same system for reckoning both days and hours 

 of the day. 



William Ellis 



