The only exceptions to this stringent rule were certain classes of men engaged in the Greenland and South Seas whale fisheries. Skilled harpooners, linesmen and boat-steerers, on their return from a whaling cruise, could obtain from any Collector of Customs, for sufficient bond put in, a protection from the impress which no Admiralty regulation, however sweeping, could invalidate or override. Safeguarded by this document, they were at liberty to live and work ashore, or to sail in the coal trade, until such time as they should be required to proceed on another whaling voyage. If, however, they took service on board any vessel other than a collier, they forfeited their protections and could be "legally detained." [Footnote: 13 George II. cap. 28. _Admiralty Records_ 1. 2732--Capt. Young, 14 March 1756. _Admiralty Records_ 7. 300--Law Officers' Opinions, 1778-83, No. 42.] In one ironic respect the gang strongly resembled a boomerang. So thoroughly and impartially did it do its work that it recoiled upon those who used it. The evil was one of long standing. Pepys complained of it bitterly in his day, asserting that owing to its prevalence letters could neither be received nor sent, and that the departmental machinery for victualling and arming the fleet was like to be undone. With the growth of pressing the imposition was carried to absurd lengths. The crews of the impress tenders, engaged in conveying pressed men to the fleet, could not "proceed down" without falling victims to the very service they were employed in. [Footnote: _Admiralty Records_ 1. 1486--Capt. Baird, 27 Feb. 1755, and numerous instances.] To check this egregious robbing of Peter to pay Paul, both the Navy Board and the Government were obliged to "protect" their own sea-going hirelings, and even then the protections were not always effective. Between the extremes represented by the landsman who enjoyed nominal exemption and the seaman who enjoyed none, there existed a middle or amphibious class of persons who lived exclusively on neither land nor water, but habitually used both in the pursuit of their various callings. These were the wherry or watermen, the lightermen, bargemen, keelmen, trowmen and canal-boat dwellers frequenting mainly the inland waterways of the country.