469 
a Theory of the Earth. 
pack them with hay into a bag destined for that purpose, 
until you have a sufficient quantity to form a box, which 
you may send home by the public carriages wherever you 
find an opportunity^; but, as it is fatiguing for the travel, 
ler to load his pockets during the time of his excursions, 
and as the guides often lose them on purpose in order to 
get rid of them, I have behind my saddle tw o leathern 
bags, into which I put them till I come to some halting- 
place, where I have time to pack them with hay into a 
bag. M. Besson recommends to those who undertake 
sea voyages to write with China ink the characters which 
ought to accompany minerals in long passages, because 
common ink may be effaced by accidents. 
8. A blow-pipe, with its apparatus. As I make much 
use of this instrument, which at length fatigues me, though 
I can blow with my cheeks without exercising my breast, 
I caused to be constructed a pair of portable double bel- 
lows, the sides of which contain each sixty-two square 
inches. These bellows can be suspended from the edge 
of a table ; and I put them in motion by pressing together, 
between my knees, the two handles, which afterwards 
separate by the action of the spring. This apparatus may 
be easily carried, and is very convenient. 
9. A graduated semicircle traced out on a copper-plate 
of a form exactly rectangular, with a plummet suspended 
from the centre of the semicircle. This semicircle, is 
the most convenient instrument for measuring the inclina- 
tion of strata, of veins and declivities ; and it may always 
be carried in a pocket of the portfolio. 
10. A compass, furnished with a cross staff, to find 
the direction of mountains, chains, vallies, and strata. 
11. Portable barometers with two mercurial thermo- 
meters; one affixed to a barometer to estimate the tempe- 
rature of the mercury in the latter, and the other with a 
bare bulb for measuring the temperature of the air. Those 
