116 BULLETIN OF THE 



the expression for the local day, and congruity would require that 

 the change of day should be at the prime meridian, which would 

 cause great inconvenience and even confusion. 



There are some observations of terrestrial phenomena, which it 

 is desirable to have made simultaneously in the same continent or 

 in all parts of the world. This was notably the case in the mag- 

 netic crusade some forty years ago, when certain instants of Got- 

 tingen times were specified ; but the observers had no difficulty, each 

 for himself, in determining and using his corresponding local time. 

 And in meteorological observations, if times are prescribed in the 

 time of any specific meridian, the observers, if of sufficient intelli- 

 gence to make valuable observations, can readily convert these times 

 into their local times, or the reverse. The constant difference of 

 longitude, expressed in time, is all that each one requires for the 

 purpose. 



The great call for a standard time has been made with regard to 

 railroads. A uniform time for each road, or connecting system of 

 roads, is needed for regulating the times of starting and the arrival 

 of trains, which each road can best determine for itself, and the 

 time-tables and clocks at the several stations may be reserved for 

 the employes of such roads only. If the time-tables published for 

 information of the travelling public are given in the local time of 

 each place, or a column of constants for the reduction of the pub- 

 lished times to the local times is given, the needs of the traveller 

 seem to be sufficiently provided for. A local time differing but 

 little from local mean-solar time is needed to meet the wants of the 

 social and industrial interests of the country, and if it be exactly 

 the mean-solar time, it varies from place to place directly with 

 the longitude. 



An essential is that each time-table for railroads should state 

 distinctly what time is used. A neglect of this has and will pro- 

 duce uncertainty and confusion. In a leading railroad guide I 

 found, at a place which I visited ,three time-tables for the same road, 

 without any statement that one of them was in New York time, the 

 others in time of other places. 



The suggestion that the dials of clocks should indicate an entire 

 day of twenty-four hours instead of a half day of twelve hours is 

 valuable to a certain extent. This is done in astronomical clocks, 

 and in the astronomical mode of noting time. It would be an im- 

 provement in chronometers for nautical use, but sufficient if the 



