Massachusetts Charitable Mechanic Association. Board of Judges.

Report of the judges of the Massachusetts Charitable Mechanic Association, on "Ridgway's revolving battery. Letters of Mrs. Ridgway and Admiral Davis, and Major King's report on the Ridgway battery. Letter of Admiral Davis asking for measures and weights, and engineer Wm. C. Hibbard's estimate thereof

Report of the judges on new inventions and machines, at the tenth exhibition of the Massachusetts Charitable Mechanic Association, on John Ridgway's vertical revolving battery, awarding a gold medal