easured with a pair of compasses
from point to point--is, taking one day with another, and including all
stoppages of every kind, whatever be their cause,--very fast travelling
for a caravan. In estimating the probable duration of a journey in an
unknown country, or in arranging an outfit for an exploring expedition,
not more than half that speed should be reckoned upon. Indeed, it would
be creditable to an explorer to have conducted the same caravan for a
distance of 1000 geographical miles, across a rude country, in six
months. These data have, of course, no reference to a journey which may
be accomplished by a single great effort, nor to one where the
watering-places and pasturages are well known; but apply to an
exploration of considerable length, in which a traveller must feel his
way, and where he must use great caution not to exhaust his cattle, lest
some unexpected call for exertion should arise, which they might prove
unequal to meet. Persons who have never travelled--and very many of those
who have, from neglecting to analyse their own performances--entertain
very erroneous views on these matters.

Rate of Movement to measure.--a. When the length of pace etc., is known
before beginning, to observe.--A man or a horse walking at the rate of
one mile per hour, takes 10 paces in some ascertainable number of
seconds, dependent upon the length of his step. If the length of his step
be 30 inches, he will occupy 17 seconds in making 10 paces. Conversely,
if the same person counts his paces for 17 seconds, and finds that he has
taken 10 in that time, he will know that he is walking at the rate of
exactly 1 mile per hour. If he had taken 40 paces in the same period, he
would know that his rate had been 4 miles per hour; if 35 paces, that it
had been 3.5, or 3 1/2 miles per hour. Thus it will be easily
intelligible, that if a man knows the number of seconds appropriate to
the length of his pace, he can learn the rate at which he is walking, by
counting his paces during that number of seconds and by dividing the
number of his paces so obtained, by 10. In short the number of his paces
during the period in question, gives his rate per hour, in miles and
decimals of a mile, to one place of decimals. I am indebted to Mr.
Archibald Smith for this very ingenious notion, which I have worked into
the following Tables. In Table I., I give the appropriate number of
seconds corresponding to paces of various lengths. I find, however,