The weapon was in appearance similar to the Maxim gun, but came with two barrels, capable of working in conjunction or separately with a discharge of 500 rpm.
It used pan magazines containing 104 rounds instead of the belt feed of the Maxim gun, which was prone to jamming.
As reported at the time: The weapon has two barrels and is chambered for the .303 British round.
The cooling jacket is similar to the Maxim gun but comes with a steam valve.
The Caldwell is lighter and simpler than the Maxim and can be field-stripped in under one minute without the use of tools.