  It has recently been shown that the $W_3$ and $W_3^{(2)}$ algebras can be
considered as subalgebras in some linear conformal algebras. In this paper we
show that the nonlinear algebras $W_{2,4}$ and $WB_2$ as well as
Zamolodchikov's spin $5/2$ superalgebra also can be embedded as subalgebras
into some linear conformal algebras with a finite set of currents. These linear
algebras give rise to new realizations of the nonlinear algebras which could be
suitable in the construction of $W$-string theories.
