Employees engaged in “cruising * * * timber” include all those members of a field crew whose purpose is to estimate and report on the volume of marketable timber. Employees engaged in “surveying * * * timber” include the customary members of a crew accomplishing that function such as the chairmen, the transit men, the rodmen, and the axmen who clear the ground of brush or trees in order that the transit men may obtain a clear sight. Similarly, the usual members of a crew which go to the woods for the purpose of felling timber and preparing and transporting logs are engaged in operations described in the exemption. Typically included, when members of such a crew, are fellers, limbers, skidders, buckers, loaders, swampers, scalers, and log truck drivers.