Experiments with Cannon^ &c. 181 



number of revolutions, and parts of revolutions, of the 

 elevating screw that answer to the given elevation. 



" 6. In order to facilitate the pointing of the gun, 

 when the wheels of the gun-carriage happen to be placed 

 upon uneven ground, there are two lines of sight drawn 

 upon the gun (one on each side of it), which are both 

 perfectly parallel with the axis of its bore. 



" The utility of these lines must be evident to those 

 who know how difficult it is to point a gun at a given 

 object when one of the wheels of its carriage is higher 

 than the other; and how much, under this circumstance 

 (of uneven ground), a gun is necessarily thrown out of 

 its true direction, by pointing it by means of fixed 

 sights, or notches, situated on the upper part of the gun. 



" By means of the lines of sight, parallel to the bore, 

 which are marked on these guns, the pointing of the 

 gun may at any time be examined and corrected ; for 

 whenever the gun is properly pointed, either of the lines 

 of sight will carry the eye either against the object (name- 

 ly, in very small distances) or perpendicularly over it. 



"7. As it frequently happens that the wheels of gun- 

 carriages are wounded and disabled in action, in order 

 that a speedy remedy may be applied in those cases, in 

 the Bavarian artillery, the wheels of the gun-carriages of 

 the field pieces are of the same form and dimensions, 

 precisely, as the wheels of their limbers, and the hinder 

 wheels of their ammunition waggons, in order that these 

 last may be taken occasionally to replace the former. 



" 8. In the construction of the new Bavarian artil- 

 lery, all useless reinforce rings upon the gun have been 

 omitted, and pains have been taken to make its form as 

 simple as possible. 



(Signed,) ff RUMFORD. 



"BROMPTON, 26th August, 1799." 



