The problem of providing protection to the gun crew during the loading of a muzzle-loading cannon has been a challenge to artillerists for as long as cannon have existed. Various methods such as counterweighed shields, baskets of earth and, of course, massive stone fortifications were used with greater or lesser success from the Middle Ages till the advent of the rifled gun in the middle of the 19th century.
With the rifled gun came two new problems to contend with — highly improved accuracy and much greater penetrating power. Experience in the field and formal experiments showed clearly that walls of brick and stone would no longer give the protection necessary.
Where brittle masonry would no longer suffice, it was found that extended, sloping earthworks were much better suited to absorbing the punishment of the new artillery. But even then, embrasures had to be left open through which the guns could be trained on the enemy or at least the gun itself had to be elevated above the rampart.
Enclosing the guns in iron casemates or turrets was also reasonably effective but extremely expensive and cumbersome with the technology of the times.
In 1858, Alexander Moncrieff (1829-1906), a captain of the Edinburgh Military Artillery, submitted a proposal which though not unique in principle was novel in design – a disappearing gun. He was requested to submit drawings and models but was unable to do so at that time and the idea was ultimately ignored.
Not until 1866 was he able to submit his design in enough detail to explain to the Royal United Service Institution how his “Method of mounting guns with counterweights and of using them in gun-pits and of laying them with reflecting sights” really worked.
His system was based on the use of curved cheek plates supporting the forward end of the gun carriage and a counterweight which allowed the gun to rotate downward during the recoil. This relatively simple mechanism made it possible for the gun to completely disappear behind a parapet or into a pit where it could be serviced in reasonable safety.
Another feature that Moncrieff’s “disappearing gun” provided was the ability to hide from the enemy the locations of the batteries. With guns placed in pits and the batteries dispersed across the terrain as he proposed, nothing would be visible to the enemy except at the actual time of fire.
However, as with many other aspects of human endeavor, this concept was taken to task by the stodgy traditionalists who were steeped in the convictions that only large fortifications with massed ordnance had any validity. Commander Dawson, a member of one of the reviewing committees, even had this interesting bit of logic to contribute – that England had no need for disappearing batteries because the Royal Navy would never allow the enemy to come that close to England’s shores.
But if England started installing Moncrieff emplacements, her enemies would be sure to follow and then the Navy would be baffled in its pursuit. So naval men would have to judge “how they would like to be opposed by guns popped up from holes in the ground which offered our seamen no target to aim at.”
In spite of all the political infighting, Moncrieff’s system was, at least partially, acceptedand guns on disappearing mountings installed in many of the forts – even in some rather remote places. In Fort Scaur in Bermuda there are two mainframe carriage cheek plates from a Moncrieff Mark II carriage; to date, the only known surviving remnants of a Moncrieff carriage of the muzzle loading era.
The only known functional Moncrieff mounting in the world is the reproduction carriage built from contemporary plans under the direction of Austin C. Carpenter and installed in Crownhill Fort in Devon, England [see Places to Visit article in this issue]. This is the installation available for visit and close scrutiny and which we will try to describe.
The Mark II carriage consists of a centrally pivoted rectangular steel frame consisting of two “I section” beams connected with cross bracing, mounted on four iron wheels set in line with the circumference of the pivoting track. The tops of the beams are set with cogs (gear teeth) approximately 2 inches x 4 inches and 1-inch thick.
Onto these frames is set a carriage consisting of two cheek plates with one radiused corner. The bottom radius and back edge of the cheeks are set with corresponding cogs that mesh with those on the base frame. At the bottom on the front, the cheeks are connected with an axle on which is slung a heavy counterweight.
At the top of the cheeks are the trunnion pockets into which the gun is mounted. Behind the cheeks, slides are mounted which connect to the gun via parallel linkages and restrain the recoil through a friction brake. This brake remains engaged when the gun is in a recoiled position for loading.
When loading is completed, the brake is slowly released and the gun is raised into the firing position by the action of the counterweight. The gun could also be winched down from firing position in instances where a final discharge was not desired — an ingenious system, using nothing but gravity as its motive force. The carriage, with its accompanying Armstrong breech loading gun, and its construction is presented in great detail in Austin C. Carpenter’s book Guns and Carriages.
Moncrieff continued designing carriages and emplacements and arguing with his detractors over the next several years. He continued to evolve the designs adding hydro-pneumatic dampening when it became evident that counterweight designs would be prohibitively heavy in the larger guns.
In 1871 he was elected a Fellow of the Royal Society, promoted to Major in 1872 when working on his carriage designs at Woolwich Arsenal and then to Colonel in 1878. He was knighted in 1890.
Yet in spite of his contributions and recognition, it is questionable how much satisfaction and fulfillment he got from his achievements. In his later years, after he had left the Department of the Director of Artillery, he had great difficulty in even getting an accurate count of how many installations of his designs existed. He had detractors and he had supporters; ultimately the “establishment” had its way. It may be lucky for them that in those early years their stubborn convictions were never put to the final test.