Demi cannon: A class of large bronze cannon 12 feet long with a 6 inch bore, firing a 36 lb shot. Used on large warships like the Mary Rose and for siege artillery.
Falconet: Small bronze cannon 4 foot long with a 2 inch bore. Usually mounted on the fore and aft castles of ships for anti personnel fire. Frequently breech loading.
***
Tudor Barrel sizes and Measures
40 gallons = 1barrel, large
20 gallons = 1barrel medium, 3 foot tall. Most common for transport and for powder.
10 gallons = 1 barrel, small
3.33 bushels = 1 gallon
10 gallons = 104 quarts
40 gallon barrel would hold 200lbs powder
20 gallon barrel would hold 100lbs powder
10 gallon barrel would hold 50 lbs powder
The majority of the barrels used in the Gunpowder Plot were 20 inches high. A Standard Gonnepowder barrel holds 100lbs. With the weight of the timber you are looking at a hundred weight in total, 112lbs. A gallon of Gonnepowder weights 2.1 times a gallon of water. For obvious reasons of safety, these barrels were not bound with metal bands. Willow and hazel withies were used instead.
***
Hounslow Heath Powder Mill
Gunpowder production at Hounslow was recorded as 1,000lbs a month, 500lbs re corned. So that would be 100 medium barrels per month, and common practice would see them shipped every month plus 50 re corned.
Forty gallon barrels cost one hundred pounds in Elizabeth’s day. For Henry’s reign, it would be more like eighty pounds considering the severe inflation of the later Tudor period.
According to one reference, there were nine thousand barrels of powder in the Tower.
A firkin is a quarter of a measure, and in theory a barrel would have four firkins worth of powder, though as with most Tudor period measures, this varied depending on location.
The Queen's Oranges Page 42