THE MANNER OF WORKING THE ELECRTIC TIME BALL, 219 
The facts I have alluded to as a basis for reasoning are, of course, not my 
own, and I shall not be deemed immodest, I hope, in saying that they are all 
well established and may be accepted as true grounds of reasoning. 
This being so, it does seem that the wonderful aurora borealis may be fully ac- 
counted for in the burning of iron-dust that gathers into great clouds, and floats 
into our flying atmosphere to be burned by the concussion. — /néer- Ocean. 
lelal YSIS; 
THE MANNER OF WORKING THE ELECTRIC TIME BALL. 
PROF. C. W. PRITCHETT. 
Dr. Case :—In an editorial note in the last number of the Kansas City 
REVIEW, attention is again called to an electric time ball for the Union Depot, 
Kansas City. 
Since June 3, we have transmitted to the Union Depot, by the Western 
Union telegraph, a daily time signal, at 4 P. M. The manner of sending it is as 
follows: At about five minutes before four o’clock we call Union Depot and 
advise the operator of the nearness of the signal. ‘This is also a monition to all 
other operators to keep off till the signals are sent and acknowledged; and by 
special instructions from the Superintendent, they are under obligation to heed 
this monition. At the proper moment, one of the brake-circuit clocks of the 
Observatory is instantaneously switched into the line through a relay, and begins 
to record each of its seconds, on every sounder between Mexico and Kansas 
City. 
The first second marks 3 h., 59 m., Kansas City mean time. 
The sixtieth second marks 4 h., Kansas City mean time. 
The 120th second marks 4 h., 1 m., Kansas City mean time. 
The sixtieth second is specially distinguished from all others by an extra 
break, interpolated by hand before it and also by a like extra break immediately 
after it. There are thus three chances for the operator to get the exact sec- 
ond, if any interruption occurs. I am glad to say that, generally, the signals 
are allowed to pass uninterrupted. Sometimes, however, they are marred by 
Operators either through forgetfulness of instructions, or through ignorance 
of them. Iam reluctant to believe that they are sometimes interrupted through 
mischief. On several occasions keys have been left open, or the line has been 
down or grounded, and hence the signals have failed. - 
A word as to the accuracy of these signals. In sending them the difference 
of time between the Meridian Pier, of Morrison Observatory, and the Union 
