Velocity of the Galvanic Current in Telegraph Wires. 163 
of transmission between St. Louis and Washington, and that one 
of the signal-pauses was confounded with the clock-pause at St. 
Louis, and the other with the clock-pause at Washington. 
wo circumstances tend to corroborate this view. 
1. The length of the clock-pause is in all these cases greater 
than the average ; and 
%. The interval between the clock and signal-pauses is neither 
too great nor too small to correspond with this hypothesis. 
There are several other points which I would gladly have dis- 
cussed ; but will however confine myself to the mention of a sin- 
gle curious fact. Reducing the velocity found by Wheatstone for 
friction-electricity in copper, by multiplying it with the ratio of the 
conductive power of the two metals, we have 51096 as the cor- 
Tesponding velocity in iron wire of the same diameter (1:75 mil- 
imeters), ata temperature of 32° F. This is to the velocity we 
have deduced, almost precisely in the inverse ratio of the sectional 
areas of the conducting wires. 
It is to be hoped that still farther materials may be collected 
during the ensuing winter by the zeal of the Superintendent of 
the Survey, and the indefatigable energy of Mr. Walker. The 
Superior insulating power of the posts in freezing weather, renders 
winter the most desirable. season for instituting experiments of 
this kind. It is a circumstance in which we as Americans may 
be warranted in feeling an honest pride that all the telegraph-ex- 
periments, excepting those of Mitchel and Fizeau, which have 
been instituted for deducing the velocity of the galvanic current 
—a result so important to science, and for the proper discussion 
of telegraph-observations for longitude—have been made under 
superintendence of the U. S. Coast Survey. 
In future experiments it appears to me highly desirable that 
Some machinery, capable of delivering several inches of paper per 
second, at a tolerably uniform rate, should be employed to move 
the fillet or cylinder on which the record is made; that the quality 
of the paper used should be as fine as possible, and that the 
_ Same circuit, which is not improbable. 
_. Uhe ordinary size of the telegraph wires is, as I understand, 
that corresponding toa weight of about 300 Ibs. to the mile. 
He new line now constructing, by the patentees of House’s 
wonderful printing telegraph, between Buffalo and New York, is 
Som pOs Wires weighing from 600 to 800 Ibs. to the mile. 
Experiments made with this line would be of great service in de- 
ning whether the velocity varies with the section of the con- 
wags Wire Very respectfully yours, 
ge, August, 1850, B. A. Govtp, Jr. 
