80 Review of the Results of the U. 8. Coast Survey. 
and even of experience, Wheatstone’s determination was sup — 
posed to hold good, at least approximately, for galvanic currents 
as well as for electricity of high tension, and for bad as well as- 
good conductors. The telegraph operations of the Coast Survey 
demonstrated at the very outset the inaccuracy of received ideas 
preparing. 
To determine the difference of longitude between Cambridge, 
Mass., and Liverpool, four distinct chronometric expeditions 
have been sent out, namely: in 1849, 1850, 1851, and 1855. In 
the last expedition the number of voyages made was six, and 
the number of chronometers sent out fifty-two. The first 
8. 
_ In connection with its astronomical and geodetical observ 
tions, the Coast Survey has been enabled at a trifling expense 
earry out an extensive series of determinations of the tr 
magnetic elements at very numerous stations. These elem 
it will be remembered are the declination, inclination, a 
zontal intensity. So great has been the amount of mate 
