576 
GEOGRAPHICAL 
I am enabled to say that the Engrwoer is entitled to the greatest credit for 
accuracy and fideUty to the original ; of which, even to the proportional 
sizes and forms of the letters, this is a close facsimile ; and with respect to 
the engraving itself, it is not necessary for me to make any remark, as that 
will sufficiently prove the talents and care that have been employed upon it. 
The explanations on the face of the map will render every part of it 
easy to be understood ; and by having added to every one of my stations, 
the date of my arrival there, it may be used with very great convenience as 
a Geographical Index to the journal, by referring to the heads of the pages 
for the corresponding date. It has for the Naturalist, the advantage of 
showing, by the name of the place, the season of the year at which the 
various objects have been met with. Some further explanation of the names 
which are here underlined, may be found at page 286 ; and for the rule by 
which the different scales are formed, the note at page 90 may be consulted. 
The days' journeys are of the usual length ; but are too great to be practi- 
cable with the same cattle many days in succession. The mode in which 
I ascertained the daily distances, is fully described at pages 289 and 290 ; 
and with respect to the astronomical observations, and the longitudes given 
in the Itinerary, pages 332, 204, and 556 contain some remarks. 
Nearly all the latitudes, were determined by observations of the meri- 
dional altitude of stars ; and this was done from a conviction that they 
admit of greater accuracy than the sun ; at least such whose annual varia- 
tion in declination have been well ascertained. For, being mere luminous 
points when viewed through the telescope of the sextant, the reflected 
image may be brought to coincide with the real, with less risk of any error 
of sight in the observer, than the edges of the sun's disk. The latter re- 
quiring the intervention of darkening glasses, have this source of error 
more than the stars ; and in addition to which may be placed the more rapid 
change of daily declination, requiring a knowledge of the longitude for its 
correction. 
The use of the stars is particularly convenient for a traveller ; as, in 
the usual practice of obtaining the latitude from the sun's altitude at noon, 
it more frequently happens that, at that time of the day, he is on his journey ; 
and even if at rest, unless at that very moment that part of the sky be free 
from clouds, he is liable to lose his only opportunity of knowing the lati- 
tude of the spot J whereas, stars coming on the meridian at all hours of the 
night, he seldom can be disappointed, if from any cause he should miss 
the moment for any particular one ; and may obtain the greatest certainty 
by taking the mean result of several stars on the same night. Or, should 
