This week we have neither a postcard nor a photograph for you, but rather a late nineteenth century etching. This etching depicts two pieces of contemporary ordnance:The upper illustration is an Armstrong 12 pounder field gun:This gun was introduced in 1859 and the gun incorporated some advanced features for its day. It was one of the first breech-loaders: shell and gunpowder propellant were loaded through the gunner’s end of the barrel, rather than through the muzzle as in previous guns, allowing a higher rate of fire. The shells were coated with lead, which engaged spiral grooves cut inside the barrel (“rifling”) and caused the shell to spin rapidly in flight and hence imparted far greater accuracy and range than previous guns. The lead coating effectively sealed the gap between shell and barrel and eliminated the wastage of propellant gases, previously known as “windage”, and hence only half the amount of gunpowder propellant as previous was required.
The barrel was of wrought iron, “built up” of a tube with additional layers heated and then shrunk over it as they cooled. The result was a “pre-stressed” barrel: the interior of the barrel was under compression from the layers shrunk over it, so that the heat and pressure of firing did not stretch it. Hence the barrel was smaller and lighter than previous guns.The lower illustration is of an older and more conventional 32 pounder, unrifled gun and carriage:This is a much older principle and similar to the cannon used during the Napoleonic era. The carriage and weight of this gun indicate it was designed to be emplaced on a fortification rather than used in the field. It has however been updated form early designs by having cast iron wheels to the carriage rather than wooden ones:It is also worth noting that the gun fires shell rather than solid shot. This design of gun carried on in service for heavy weapons for longer than the lighter field pieces. Early breach loaders were not always very safe at the breach end with heavy charges- metallurgy at the time being limited. The heavier and more solid breach end of a muzzle loader was far safer for heavy charges. This illustration comes, I suspect, from a contemporary book or journal. I would like to get this one framed up at some point as it would look rather nice on the wall but my ‘framing pile’ seems to just get larger!