It is shown that the net mechanical impulse one must exert to change one static system of currents and charges slowly into another such system is independent of the method used, and is given by the change inΣqiAT(xi,t), whereAT(xi,t)is the transverse vector potential, evaluated at the positionxiof the chargeqi. The linear momentum stored in a quasistatic electromagnetic field is thus given byΣqiAT(xi,t). These considerations show that it is possible to give the transverse vector potentialATof a static system a physical meaning. Namely, thatAT(x)is the net mechanical impulse one must exert to bring a unit point charge slowly from infinity to the pointx.