Let me pick up where I left off, several months back, discussing the Hotchkiss brothers and their ordnance patents. Recall from those earlier posts, Andrew K. Hotchkiss possessed a keen mechanical mind. He was behind the first set of patents issued to the brothers. Specifically, Andrew’s name is associated with a rifle projectile using three parts – the main body, a lead ring, and a tail cup. And when fired, the force of the charge pushed the cup to expand the lead ring, thus forcing the projectile into the rifling. However, Andrew, who was born crippled, died in 1858 at the age of only 35.
His brother, Benjamin B. Hotchkiss, who might best be described as an entrepreneur/inventor, continued the work on ordnance. And we see that name associated with improvements to the pre-war Hotchkiss rifle projectile (and canister refinements). Throughout the evolution, the basic design remained – main body, lead ring, and tail cup. And Benjamin used that design to create solid shot, shell (with timed and percussion fuses), and case shot. The nomenclature of the case shot intrigues me, as the Ordnance Department referred to them as “bullet shells” in the summaries.
Now the basic premise of a bullet shell… er… case shot was to simply take a normal shell and fill it with sub-projectile balls (iron, but more often lead) and set off with a bursting charge while in flight (with a carefully set fuse), so as to scatter the sub-projectiles across the target. We see these sometimes referred to as shrapnel after General Henry Shrapnel of the British Army. But as no weapon design is perfect, there were problems with that basic recipe.
First off, the sudden movement when the shrapnel/case shot was fired could cause the “bullets” to rub against the powder. Such lead to premature explosions… not good for the crew serving the gun. One refinement was to simply seal off the powder behind a diaphragm. But that reduced the bursting charge and still left the bullets rattling around, possibly sparking against the cast iron body. Another refinement was to place the bullets in some non-explosive solution (resin or sulfur for example) that cooled and hardened, thus gluing the bullets into place. But this also reduced the room for the bursting charge and further introduced more (though slight) resistance to the bursting. Not to mention, the bursting charge itself remained loose and might possibly ignite due to rasping (the friction of the powder against it’s containing structure).
The problem with filling case shot (and shells in general) was more pronounced with rifle guns where the movement was on three axis. Benjamin advanced his solution to this in Patent Number 35,153, issued on May 6, 1862:
My improvement relates to the contents or filling of the projectile, and to the adhesion of the same to the inclosing [sic] part, and it applicable to all forms and constructions of explosive projectiles.
The first feature of my invention is attained by solidifying the powder in the shell by use of collodion or an equivalent adhesive material not by its presence destructive to the explosive character of the powder, so as to prevent the friction of the powder upon itself and upon the sides of the shell or balls … to prevent a displacement of the powder from interfering with the proper action of the exploding apparatus in percussion-shells.
The nature of my invention also consists in causing the filling of an explosion projectile to adhere firmly to the sides thereof by employment of a solution of shellac or other proper adhesive substance… whereby the said filling is compelled to rotate with the shell, and much friction and danger of premature explosion avoided.
In essence, Benjamin Hotchkiss added something to the powder turning it into the glue to hold the bullets in place. And he further cemented the payload with a generous application of adhesive to the shell interior.
Hotchkiss described the construction as such (my parenthesis and emphasis added to the figure references for clarity):
(A) is the body of the projectile, which may be made in any of the approved forms. (P) is the powder. (B) are bullets interspersed with the powder….
The manner of filling as shell to produce the advantages of my invention is as follows: I first pour into the shell a solution of shellac in alcohol, and coat the whole interior therewith, as indicated by a brown line, (C). While this is still wet, I place in the balls (B), if there are any to be used, and then fill all the interstices with the powder (P). I then pour into the shell a sufficient quantity of “collodion” (gun-cotton dissolved in ether and alcohol) to fill all the interstices, and place the shell away to dry. The alcohol and ether readily evaporate and leave the charge in a solid mass, the collodion serving as a cement to hold the grains of powder together, but offering no serious obstruction to the proper and rapid action of the fire when it is desired to explode the same. This solidified powder holds the balls (B) firmly in place… and the whole is cemented to the sides of the shell by the cement (C), so as that on firing the shell from a gun there is little or no liability of the powder becoming prematurely igninted, either by friction among the balls or its own particles against themselves or the sides of the shell or by backward motion of the exploding device.
Hotchkiss noted that while he was not the inventor of collodion, nor the first to use collodion to solidify gunpowder, he was the first to propose such use in a shell.
Clearly Hotchkiss had a viable solution to the cited problems – movement of the payload inside the shell. But as is always the case, the soldiers in the field always find another problem to be solved. The more gunners used case shot from their rifles, they began to notice poor shot patterns on the distant end. When a spinning projectile explodes, the sub-projectiles and fragments disperse laterally and not directly on the line of flight. Good artillerists looked for a way to project the sub-projectiles directly forward along the line of flight. We might consider this as producing long range canister.
That requirement lead to another Hotchkiss patent:
… and ammunition for another post in this series.