Page 10 - Moncrieff's Disappearing Guns
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Moncrieff’s Disappearing Guns                                                                            David Moore

           Colonel Adair and the use of Iron in Fortification  The 1869 Committee
           On Friday June 19th. 1868, Colonel Shafto Adair,   The 1869 ‘Report of the Committee on the
           Deputy Director of Works for Fortifications, read a  Construction Condition Cost of the Fortifications’
           paper to the Institution on ‘Coast Defences and The  reported that the works for land defence had been
           Application of Iron to Fortification’.             completed with only the parapets formed. It was not
           In it he stated that Moncrieff’s carriage was:     intended to cut the embrasures or lay the racers for
           ‘a very important invention with regard to         the guns until the need arose for mantling the works
           gun-carriages, which, probably will very greatly   and placing them in a state of defence. The
           affect the construction of the parapets of open    Commission therefore was of the opinion that the
           batteries and which, though not a substitute for   measures necessary for adapting them to the
           turrets in all cases, will afford the advantage of  Moncrieff system and the strengthening of the
           lateral range obtainable from turrets and guns on  parapets could be safely deferred until the details of
           turntables, or en-barbette, without exposure of the  the Moncrieff system were more fully worked out.
           gun to direct fire, except at the time it is being laid
           and discharged.’                                   The introduction of the Moncrieff carriage was seen
                                                              to have an important bearing on the resisting power of
           Adair thought that the great point of this invention  some of the works in which it was proposed to adopt
           was that it enabled the protection of guns in open  it. Designs for the adaptation of these works to this
           batteries by a parapet un-weakened by openings and  system were laid before the Commission, in some
           thus having the advantage of the great lateral range of  cases as approved plans, subject only to the condition
           barbette batteries even at low level above the water  that the gun carriage should prove as suitable for
           without exposure, except at the moment of firing. It  heavier guns as for the seven ton gun; in others as
           also avoided the use of iron shields at the embrasures  alternative plans subject to further consideration.
           of open batteries and so would save great expense.  An appendix to the report tabulated the works for
                                                              which the Moncrieff system was to be applied
           He doubted if the Moncrieff carriage would be more  showing the financial effects and changes in
           costly than the muzzle-pivoting carriage (which was  armament.
           necessary to afford the smallest opening for an
           embrasure) and the Moncrieff carriages when        Four classes of batteries were proposed as suitable for
           supplied in numbers could not be equal to the cost of  the system:-
           iron shields for existing works.                      1st. Batteries en barbette
                                                                 2nd.Batteries with open embrasures
           Adair believed that should the Moncrieff design be    3rd. Batteries with embrasures to be protected by
           adopted by the artillery authorities it could be         iron shields.
           employed in all the open batteries in which it was    4th. Casemated batteries.
           proposed to provide iron shields. He witnessed the
           trials of Moncrieff and afterwards submitted       In some cases it was proposed to mount Moncrieff
           proposals for the application of the invention to  guns in place of revolving turrets.
           several of the new works of fortification including the  The Commission appears to have been in favour of
           ones on Portsdown Hill, Portsmouth, taking Fort    the Moncrieff system because of relative costs. This
           Purbrook as an example.                            was £1,075 for the pit and magazine, £1,345 for the
                                                              carriage and about £500 for the 7-inch gun. Compared
                                                              with the cost of an armoured casemate the Moncrieff
                                                              system showed great savings. The Commission
                                                              calculated that £194,159 could be saved over the
                                                              whole fortification programme.

                                                              Moncrieff was called before the Commission to state
                                                              his opinion on the Thames forts and the proposals to
                                                              adopt his system to them. The Commission concluded
                                                              from Moncrieff’s reports that he looked upon these
                                                              designs as exhibiting in a very inferior degree, those
           The Moncrieff Mounting applied to the parapet of a  advantages which his system was calculated to afford.
           fort: Fig 5 taken from ‘Coast Defences and The     The 1869 report contained an appendix by Colonel
           Application of Iron to Fortification’ by Adair.    Jervois (Deputy Director of Works for Fortifications)
                                                              which was a return showing the Works in which it

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