ever be found considerably
decreased by the time they have arrived at a bearing state. Another
important object of consideration in these matters is the comparative
state of a residency at any particular period with what may be justly
considered as its medium state. There must exist a determinate proportion
between any number of bearing vines and such a number of young as are
necessary to replace them when they go off and keep up a regular
succession. This will depend in general upon the length of time before
they reach a bearing state and during which they afterwards continue in
it. If this certain proportion happens at any time to be disturbed the
produce must become irregular. Thus, if at any period the number of
bearing vines shall be found to exceed their just proportion to the total
number, the produce at such period is to be considered as above the mean,
and a subsequent decrease may with certainty be predicted, and vice
versa. If then this proportion can be known, and the state of population
in a residency ascertained, it becomes easy to determine the true medium
number of bearing vines in that residency.

There are, agreeably to the form of the survey book, eleven stages or
classes of vines, each advanced one year. Of these classes six are
bearing and five young. If therefore the gardens were not liable to
accidents, but passed on from column to column undiminished, the true
proportion of the bearing vines to the young would be as six to five, or
to the total, as six to eleven. But the various contingencies above
hinted at must tend to reduce this proportion; while, on the other hand,
if any of the gardens should continue longer than is necessary to pass
through all the stages on the survey-book, or should remain more than one
year in a prime state, these circumstances would tend to increase the
proportion. What then is the true medium proportion can only be
determined from experience, and by comparing the state of a residency at
various successive periods. In order to ascertain this point a very
ingenious gentleman and able servant of the East India Company, Mr. John
Crisp, to whom I am indebted for the most part of what I have laid before
the reader on this part of the subject, drew out in the year 1777 a
general comparative view of Manna residency, from the surveys of twelve
years, annexing the produce of each year. From the statement it appeared
that the proportion of the bearing vines to the whole number in