208 Coast Survey Report for 1853. 
open ocean tidal observations, on a shoal a mile and a half from 
land. (Appendix No. 15.) The excellent results from Saxton’s 
gauge lead to high expectations from the records now regularly 
received from three permanent and three movable Saxton ganges, 
Operating on our Western coast. The importance of separating 
the true tide wave from the heaping up of water along shore, leads 
us to watch with peculiar interest the off-shore observations and 
to hope for their success at much greater distance from land. 
Longitude operations.—It is now esteemed essential where 
practicable, in conducting the survey, to refer at least one principal 
Station in each section, to the central longitude point (Seaton sta- 
tion, Washington), by a telegraphic determination of longitude 
differences. During the year 1853, operations were conducted 
for thus connecting Charleston with Seaton station, the longitude 
difference already found by Mr. Walker in 1850, being only a 
preliminary determination. Such was the imperfect condition of 
insulation of the telegraph wires, as found by repeated trials, that 
it became indispensable to establish an intermediate station and 
Raleigh was thus occupied. Dr. B. A. Gould’s report of these 
Operations is given in Appendix No. 33. Some observations were 
also made on the velocity of the galvanic wave, atid the personal 
eqnatious of the observers were duly compared. Charleston will 
soon be in turn similarly connected with New Orleans. : 
Prof. B. Peirce reports (Appendix, No. 31) the results of his 
investigations and of some observations made under his charge, 
for the purpose of ascertaining a method of determining, “the 
longitude from observed transits of the moon, which shall not be 
involved ia the great and singular errors of the lunar ephemeris.” 
After stating the faults of the present methods, in which standard 
corresponding observations of moon culminations are interpolated, 
he concludes that as the existing lunar theory will not stand the 
test of observation, a correct ephemeris is not now practicable. 
He then, from three hundred and sixty-seven special comparisons, 
determines the standard probable error of an observation of 4 
the wires of the Cambridge equatorial were simultaneously ' 
corded by two spring governors, differing one-tenth of 2 second 
