In a trigonometrical measurement of the difference in level of two stations P and Q, 8 10480 m apart,

In a trignometrical measurement of the difference in level of two stations P and Q, 8 10480 m apart, the following data were obtained. Instrument at P, angle of elevation of Q = 0’ 15” Instrument at Q, angle of depression of P = 3’ 33” Height of instrument at P = 1.42 m. Height of instrument at Q = 1.45 m. Height of signal at P = 3.95 m. Height of signal at Q = 3.92 m. Find the difference in level between P and Q and the curvature and refraction correction. Take R sin 1” = 30.38m