96 
extended systematic observations of direction and intensity of 
terrestrial magnetism were carried on; and on the first of 
each month, during preappointed hours, the fluctuations of 
the magnetic declination were watched, simultaneously with 
corresponding observations by the Coast Survey on the 
Atlantic and Pacific coasts of the United States, to discover 
whether these fluctuations showed indications of synchronism 
in the two hemispheres. The last of the six quarto vol- 
umes which record the results of the expedition is already 
published, and devoted to the meteorological and magnetic 
observations, and their tabular discussion. 
The first volume of this series contains an elaborate 
treatise upon the physical and social characteristics of Chile, 
its commerce and its resources. The second volume begins 
with the narration of Lieutenant MacRae of a journey home- 
ward and back across the Andes and Pampas. After the com- 
pletion of the magnetic observations in Chile, they were 
placed in charge of Lieutenant MacRae, who was instructed 
to carry them across the Andes and the Argentine territory, 
returning home by the way of Buenos Ayres, making regular 
observations on his way for determining elevations, geograph- 
~ 8 1 positions, mag i Sac logi = ta, for each 3,0) 
feet of ascent and descent, and for each hundred miles of 
longitude ; and collecting at the same time, such other ge0o- 
graphical and statistical data as he could. These ingieae 
tions were well carried out by Lieutenant MacRae, but nee 
mountain-barometer having been broken on the way; and his 
chronometers so much injured as to impair his reliance oD 
them for longitudes, he offered on his return to retrace the 
. . 
_ journey at his own expense, and repeat the observations, 
provided a new set of instruments could be supplied. be one 
: was at once acceded to by the Secretary of the Navy, and se 
ou ays for the transportation authorized. The descriptio? 
aw 
