Match the following:
$$
\begin{array}{ll|l}
\text{Instrument} & & \text{Measurement} \\
\hline
P & \text{Flat jack} & 1.\ \text{In-situ stress in rock} \\
Q & \text{Borehole deformation gauge} & 2.\ \text{Load} \\
R & \text{Tape extensometer} & 3.\ \text{Bed separation resistance} \\
S & \text{Bore hole penetrometer} & 4.\ \text{Roof convergence} \\
\end{array}
$$