THE ELECTRIC TIME BALL AT KANSAS CITY. 611 
something of the equipment of the observatory and the nature of the instruments 
upon which depends the accuracy of the time now being distributed each day to 
Kansas City. 
‘«In the accurate determination of time there is necessary, in the first place, 
a good telescope, mounted firmly in the meridian, and known as a transit instru- 
ment. Fixed in the focus of this firmly mounted telescope are fine spider lines 
set perpendicular to the daily motion of the stars. The telescope being set upon 
a star, the daily revolution of our earth upon its own axis causes the stars to appear 
to move across the field of the instrument, and an observation of its transit across 
the threads of the transit instrument, after being corrected for the small instru- 
mental errors, affords the most accurate means known for the determination of 
the clock errors, or, in other words, of the time. The standard clock itself is 
rarely changed, but its error is allowed to accumulate slowly from month to month. 
In sending the time, however, a different time-piece is used, which is compared 
with the standard clock just before the time of sending. In addition to the transit 
instrument and clock, most well equipped observatories of the present time are 
provided with a chronograph—an instrument for automatically registering by 
means of electricity both clock-beats and observations of star transits. The one 
in use in the Morrison Observatory was made by Alvan Clark & Sons, Cambridge, 
Mass., and the observations of transits are read off to the one hundredth part of a 
second, and time determinations are made to within that limit of error. The 
instrumental equipment used in Morrison Observatory time determinations is not 
surpassed by any observatory in America. The transit instrument itself is one 
of the largest and most firmly mounted. It is in most respects a duplicate of the 
instrument in use at the Royal Observatory at Greenwich, England, and was made 
by the same makers. Its cost in the shop in London was $4,500 in gold. The 
standard clock by Frodsham, London, and the chronograph, by Clark, cost in 
addition $1,000. These instruments—as good as can be made by modern scien- 
tific appliances—are capable of determining time as accurately as is possible in any 
observatory in the world, which may readily be distributed to any railroad or city 
in the west. 
_ ‘The errors of the clock having been once determined, the distribution of 
correct time over the railroads and to telegraph offices is a very simple matter. 
In the method now pursued the local time is first changed into Kansas City time 
by applying the difference of longitude. At thirty seconds before 12 m., Kansas 
City time, each day, one of the break circuit clocks of the observatory is made to 
beat simply by turning a switch on the main line of the Western Union telegraph 
and the clock instantly commences to beat seconds in every telegraph office in 
Kansas City and along the line. At exactly 12 o’clock a double beat is given 
and the clock continues to beat till thirty seconds after, when it is shut off. The 
operators or any who may come to the offices to compare time-pieces, have thus 
three separate seconds which they can identify—the beginning second, which is 
thirty seconds before 12 o’clock ; the double tick exactly at 12, and the last second 
