There is no force used. The racquet simply meets the oncoming
ball and stops it. The ball rebounds and falls of its own weight.
There is little bounce to such a shot, and that may be reduced by
allowing the racquet to slide slightly under the ball at the
moment of impact, thus imparting back spin to the ball.

Volleying is a science based on the old geometric axiom that a
straight line is the shortest distance between two points. I mean
that a volleyer must always cover the straight passing shot since
it is the shortest shot with which to pass him, and he must
volley straight to his opening and not waste time trying freakish
curving volleys that give the base- liner time to recover. It is
Johnston's great straight volley that makes him such a dangerous
net man. He is always "punching" his volley straight and hard to
the opening in his opponent's court.

A net player must have ground strokes in order to attain the net
position. Do not think that a service and volley will suffice
against first-class tennis.

I am not a believer in the "centre" theory. Briefly expressed the
centre theory is to hit down the middle of the court and follow
to the net, since the other player has the smallest angle to pass
you. That is true, but remember that he has an equal angle on
either side and, given good ground strokes, an equal chance to
pass with only your guess or intention to tell you which side he
will choose.

I advise hitting to the side-line with good length and following
up to the net, coming in just to the centre side of the straight