Geology.] 
NATURAL HISTORY. 
629 
cotton are necessary ; and small wooden boxes (like those used 
for holding’ wafers) are sometimes required. For distant carriage, 
strong wooden boxes, casks, or baskets. 
The following are either essential, or useful in various degrees, 
for obtaining and recording observations. 
Pocket Memorandum-Books, of sufficient size to admit sketches. 
A Pocket Compass. 
A Measuring-tape, of fifty feet, or more. 
A Telescope. 
A Camera Lucida. 
A Box of Colours. 
The best Maps should always be sought for ; — And, the true 
economy to the traveller being that which saves time, it is best to 
mark, or even colour the map, in the field. Notes inserted on 
imperfect maps, or deduced afterwards from memoranda, are less 
authentic ; and the process is frequently neglected. 
Portable-Barometers, with detached thermometers, are desira- 
ble ; and the best instruments are ultimately the cheapest. But, 
unfortunately, barometers of every construction are very easily 
damaged or deranged. — The accurate determination of heights, 
however, though very interesting to physical geography, is com- 
paratively of little importance to the geologist. 
If the collector be a surveyor, he will know best to what purpose 
a Pocket Sextant, or small Theodolite, is applicable : — the mea- 
surement of distances, — of heights, — and of the inclination of 
strata, &c. 
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