The relations amongst the three elements of earth's magnetic field, namely horizontal component $\mathrm{H}$, vertical component $\mathrm{V}$ and $\operatorname{dip} 8$ are, $\left(B_{E}=\right.$ total magnetic field) (1) $\mathrm{V}=\mathbf{B}_{\mathrm{E}}, \mathrm{H}=\mathrm{B}_{\mathrm{E}} \tan \delta$ (2) $V=B_{E}$ tan\delta, $H=B_{E}$ (3) $\mathrm{V}=\mathbf{B}_{\mathrm{E}} \sin \delta, \mathrm{H}=\mathrm{B}_{\mathrm{E}} \cos \delta$ (4) $V=B_{E} \cos \delta, H=B_{E} \sin \delta$