One of the best parts of our job is discovering a helmet with a touch of mystery! At first glance this helmet appears to be a classic 1930's A. Schrader's Son 4 light 12 bolt helmet - but there is a lot more to this one!

 

This helmet actually started off as a 5 bolt model helmet! Four and five bolt style helmets were offered by Schrader during the late 19th and early 20th Centuries. The US Navy actually used the five bolt pattern Schrader helmets and defined them in 1916 as the US Navy Mark II. In many cases the bolt style helmets were modified or updated by the US Navy. The updates actually involved quite a bit of work that was preformed by either Morse or Schrader. The update involved removing the large thick neck rings and replacing them with a threaded or interrupted thread style neck ring - common on most all copper / brass helmets in the 20th Century.

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Once all the work was done the US Navy in the 1916 diving manual defined the Mark IV helmet as "bolt type, wide breastplate, screw face plate, oval top and side windows, Schrader type regulating esape valve, telephone, safety valve, and air inlet connection, manufactured by A. Schrader's Son Inc, Brooklyn, NY, interrupted screw type.

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​It's quite possible the US Navy had the helmet updated to the Mark IV configuration due to bolt helmets being an obsolete style by the 1930's. Bolt helmets simply could not create enough force on the neck ring gasket to provide enough seal against water leaks. A threaded helmet would tightened down and a good gasket would generally always provide a water tight seal. 

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The helmet is in very nice condition and perfect for display in the home or office. The copper body and brass hardware were polished out years ago, leaving a bright clean appearance showing off all the aspects of the piece. The helmet is complete with all its glass (one cracked but solid), 12 wing nuts, four brails (one appears slightly different color of brass than others), exhaust valve, air fitting, communications fitting, dumbbell safety latch, window guards, neck ring gasket and internal air vents. A period repair on the back of the bonnet is evident by a soldered circle and copper patch. This would be a very rare opportunity to acquire a Mark IV with the goal of finding an example of each Mark helmet 1 through 5.