76 



note 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, 1847, and in the recent report of the 21st 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 explica- 

 ble by any admissible value of relative times of operations, of the 

 spiral spring and receiving magnet, armature. Neither do they ap- 

 pear to be explained 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 the- 

 ory of this subject was given by Mr. Walker, Dec. 28, 1847, in his 

 Report on the Telegraph operations of 1847. 



These several sources of error are nearly all eliminated by the 

 manner 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 remarked, that the outward and inward armature times of the 

 magnets of the local registers, are relatively annulled by their having 

 the same value for the clock and signal electrotomes. 



According to Mr. Walker's report^ these residual quantities, from 

 change of relative place of origin of the clock and signal waves, may 

 all be explained by the hypothesis that the time of propagation of the 

 galvanic wave from the place of the clock or star signal stations, to 

 that of the receiving register, though small, is not quite insensible. 

 A solution of the eighteen equations of condition formed on this hy- 

 pothesis, by Mr. Walker, give, for the velocity of the propagation of 

 the galvanic wave, through the compound circuit, eighteen thousand 

 eight hundred miles per second, with a probable accidental error, as 

 stated by him, of about one thousand miles. The statistics are too 

 incomplete to warrant any discrimination between the times of pro- 

 pagation of the wave through the different kinds of media, viz., the 

 wires, the batteries, (three in number,) and the ground. After apply- 

 ing the values of the wave-times by this hypothesis, and with this 

 velocity in the different portions of the whole circuit of one thousand 

 and fifty miles, no sensible discrepancy remains, the residual terms 

 being not greater than their probable errors, from the comparison of 

 the two Washington registers. All the readings now harmonize as 

 well as if all the clock and star signals, and all the printed records 

 had been made in the same place. 



