Let kthcell has surface area 
and is bounded path Lk while the total area is bounded by path L. As seen from the figure that if we evaluate the sum of the line integrals around the elementary areas, there is cancellation along every interior path and we are left the line integral along path L. Therefore we can write,
..............(1.83)
As 
0
. .............(1.84)
which is the stoke's theorem.