Here is another unlisted Frank Dengal Shawano, WI. hutch (Not in Roger Peter's book)!  This bottle appears to have an earlier shape with sloping shoulders and a different glassmaker.  The  glassmaker's markings are even embossed on the base instead of the heel as with the majority of Wisconsin hutches. 

Embossed, "Frank Dengal, Shawano, WIS."

Color-Aqua

Size-Half Pint

Glassmaker-W.F.& S. MIL. "embossed W.F.& S. MIL around a 4 point navagation star on the base of the bottle." 

Date-c.1898-1899?-I would guess this to pre-date the c.1900-1902 "S.B.& G.Co." variant in Roger Peter's Book.  I think that the navagation star was maybe used from c.1896-1900 for William Franzen & Sons before he changed the Northern Glass Co. outfit into his own.  He did use his initials as early as 1896 when the glassmaking company named Northern Glass Co.  However my guess on the date of this variant predating #7904 is only my opinion.