John Breed, Diary and Training diary, item 74

• March 27, 2017 03:19:04 Cheryl Ellsworth

  Jump; The angle between the Line of Departure and

  the axis of the axis of the piece before firing. It is due to

  the vertical movement of the gun on firing

                                                    

  N.B; Jump arises from the gun and carriage + shooting

  in a vertical plane on its point of support in rear,

  when the gun is fired and takes effect before the

  projectile leaves the bore

  With no jump the Jump of Departure, and the 

  axis of the piece before firing would be identical

                                                    

  Angle of Descent; The angle which the trajectory makes with

  the Line of Sight at the point of their second

  intersection, or in other words it is the angle

  made by a tangent to the trajectory at the

  point of impact with the horizontal plane

                                                    

  Slope of Descent; The angle of descent is sometimes called

  Slope of Descent and expressed as 1

  in 10 or 1 in 12. This means that the shell

  at the end of its trajectory falls 1 foot

  vertically whilst travelling 10 or 12 feet      

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