Wang homomorphism ($\Delta :H_i(F)\to H_{i+n-1}(F)$)

For a fibration over $S^n$, the only possible differential in the homological Serre spectral sequence is $d_n$. Identifying its two nonzero columns with the homology of the fiber gives the Wang homomorphism $\Delta$.

For a fibration $F\to E\to S^n$, the Wang homomorphism belongs to the exact sequence