Grupp— Time Signals. 43 
In the case under consideration, however, where the number of 
rooms, and therefore of clocks, amounts to so large a number as 200, 
it is evidently important to simplify and keep down the cost of 
each individual clock; therefore, it will probably be found more 
economical to run an additional wire through the various rooms, 
and use two distinct currents, one of which will supply the small 
necessary motive power for driving the wheelwork, which, in this 
case, may only mean the few wheels and pinions necessary for 
the dial-work; and the other current to work, once a minute, 
the escapement which allows the hands to move forward at each 
minute. 
This latter arrangement has many advantages; and it can 
easily be arranged that an overplus of winding power be sup- 
plied, so that even if there be one or two, or even five or six, 
misses in each minute, there will still be ample left to do the 
necessary work, and there need be no error. As it is very 
unlikely that a greater number of failures than this will 
ever occur in one minute, practically the only danger is, that 
of the other or minute current missing—that which allows the 
hand to move forward. As there are only 1442 of these in the 
24 hours, as against 86,400 of the others, the danger is pro- 
portionately less; but to avoid even this danger, I have devised 
an arrangement by which, if the minute current should by any 
chance fail, the escapement will be let off mechanically a second or so- 
after it ought to have been let off electrically, the result being, that 
that particular minute will be late by one or two seconds, but 
there will be no cumulative error, and when the next minute 
eurrent comes it wipes out the error completely. 
In this clock, therefore, it is possible to actually disconnect 
the wires for several seconds during any part of the minute, and 
still the clock will show correct time. 
I would suggest that this last form be used in the more 
important positions, and the simpler form for the rest. 
[Expianation or Puares. 
