

Miscellaneous Intelligence. 143 



attached to the minute wheel, and giving its signals every two and a 

 half minutes. The other (used for the occasion) was on the plan in- 

 vented by Dr. Locke, in 1848, and attached to the escapement-wheel. 

 The automatic clock register was graduated to two seconds, usually 

 occupying an inch of paper of the Morse's registering fillet. 



Mr. Walker reports, that a comparison of sixty records, made by the 

 two registers at Washington, shows that the probable error of the me- 

 chanical operation of printing and reading off, is only about fifteen- 

 thousandths of a second. 



This confirms the estimate of accuracy of the work made by him in 



his report of Dec. 15th last, viz., of a hundredth of a second for the 



case of an automatic register of single seconds, with an inch of paper 

 to each. 



It further appears, from the Report, that when the star-signals were 

 given at Philadelphia, so that the clock and signal-waves had the same 

 local origin, all the registers at all the stations, marked alike, within 

 such limits as were indicated by the probable error just mentioned. 



When, however, the star-signals were given at New York, small, 

 but appreciable, differences were noticed in the respective readings of 

 the apparent date of the same event as recorded at the different stations. 

 This discrepancy was still greater for the case of the Cambridge star- 

 signals, the graduating clock always remaining at Philadelphia. 



The following table contains the mean excess of the readings of the 

 date of each event in the time of the Philadelphia automatic clock at 

 each station, over that of each of the others, with the number of single re- 

 sults, and the probable accidental error from the source already referred 

 to. The stations compared are denoted by their initials. Those marked 

 W, are for the mean of the two records made at Washington. A further 

 revision of these quantities may somewhat change their amounts. 



Two kinds of readings were made, viz., break circuit signal readings 

 on a break circuit, clock scale, and make circuit signal readings, on a 

 Make circuit clock scale. 



The excess indicated by the mean of the two series of readings for 

 the two scales, with the number of results and probable error of each, 

 are reported as follows. The times A, B, C and D, respectively de- 

 mote the time of passage of the galvanic wave between W and P, P 

 and N, N and C, C and W. 



For reasons connected with the analytical theory of longitudes, by 

 telegraph operations, as published in Mr. Walker's report of Nov. 10, 

 !&47, and in the recent report of the 2 1st ultimo, the mean of the two 

 series is the most plausible value that can be derived from the printed 

 record. The residual quantities do not appear to be explicable by any 

 admissible value of relative times of operations, of the spiral spring 

 and receiving magnet, armature. Neither do they appear to be ex- 

 plained by any reasonable hypothesis of relative changes of apparent 

 dates from changes of permanent magnetism, as it is called, by change 

 of locality of signal station. The analytical theory of this subject was 

 given by Mr. Walker, Dec. 28, 1847, in his report on the telegraph 

 derations of 1847. 



These several sources of error are nearly all eliminated by the man- 

 ner of forming the residuals of these tables, and being in their nature 

 Periodical, disappear in the average of all the results. It may also be 



