A system HW of normal modal logic, developed by R. Bigelow & R. Pargetter is presented. Some formal issues concerning the system are examined, such as completeness, number of distinct modalities and relations to other systems. Some philosophical topics are also discussed. The Authors interpret the system HW as the system of physical (nomic) modalities. It is questioned, whether or not the system HW is justified to be claimed to be the logic of physical necessity. The answer seems to may (...) be negative. (shrink)