Sampson "Perfex" Coil Plug..... circa 1905

A while back, I displayed a few rare spark plugs, such as the "make and Break" plug from Europe. This plug is American. It is commonly called a "Coil Plug". It was made by the Sampson Electric Co. - Canton Mass. It is their "Perfex" model B pat. 1905. It is 6" long and is 2" in diameter. It has 1/2" tapered pipe threads like a ford model "T" used. To the best of my knowledge, it operates very similar to a model "T" buzz coil. Adjustments of the spark is made by turning the brass cap to obtain a hotter or cooler spark. The large body of the spark plug is made of a fiber (probably for insulation.
They were often used in motorboat engines, and also some trucks
A very interesting spark plug and also quite rare