Calculate the refractive index of the material of prism A.

$n = \frac{\sin\left(\frac{A+\delta_m}{2}\right)}{\sin\left(\frac{A}{2}\right)} = \frac{\sin\left(\frac{60^\circ+34^\circ}{2}\right)}{\sin\left(\frac{60^\circ}{2}\right)} = \frac{\sin(47^\circ)}{\sin(30^\circ)} = \frac{0\cdot7314}{0\cdot5} = 1\cdot463 \approx 1\cdot47$.