570 Transactions of the American Institute. 



3d. The method of printing double or single numbers without stop- 

 ping the type-wheels ; 4th. The method of striking the blow, indi- 

 rectly using the spring of the hammer ; 5th. The method of elevating 

 and locking the hammer. The minor details for paying off the paper 

 fillet, inking the type, etc., may be accomplished in various ways. 



The battery power required is about the same as for an ordinary 

 chronograph. Three Grove elements or six Hill's elements, work the 

 two electro-magnets well. A separate battery of about the same size 

 is used for the hammer and fillet magnets. 



In point of accuracy, this machine leaves nothing to be desired, 

 and is much beyond what we thought possible. From a vast number 

 of experiments, made by recording automatically the beats of the 

 standard clock, both at the middle and end of the oscillation, the 

 mean error for a single print is found to be about 0.013 seconds, equal 

 in this respect to the recording chronograph. The maximum differ- 

 ence in the records of the beats seldom exceeds 0.03 seconds ; and we 

 believe this is as much due to the irregularity in the clock connection 

 as in the running of the machine, since the same thing is found in 

 ordinary chronograph records, when the measures are made from 

 second to second. 



During the building of the machine, which was accomplished by 

 my assistant, Mr. Foreman, and myself, the past winter, as we could 

 find the time, a great many experiments were tried in the method of 

 regulation, printing, etc. The fast moving train was used to propel 

 the integer seconds and minute type-wheels, dispensing with the 

 auxiliary movement, but the disturbance of its motion was consider- 

 able, especially at the end of every minute, when it had double duty 

 to perform. We think, however, by taking the power from the shaft 

 turning once in a minute, and giving uniform motion to the type, it 

 might be successful; but nothing would be saved in the amount of 

 machinery, and the liability of losing integer seconds from accidental 

 disturbance would be a serious imperfection in the method. As now 

 constructed, there is hardly a possibility of error in the integer 

 seconds without a serious disarrangement of the mechanism. If the 

 fast-running train is stopped entirely, it only requires about six 

 seconds to bring it again in coincidence with the clock pendulum. 



The saving of time and labor by the use of a printing chronograph 

 is very considerable. At the lowest estimate, it does work equivalent 

 to the labor of one person where three are employed at the same 

 time. In our zone work in former years, when the zone extended 

 two hours in right ascension, it usually requires the labor of two per- 



