PROCEEDINGS OF THE POLYTECHNIC ASSOCIATION. 441 



and are bolted to the stock or upper end of the trail. They are also connected 

 by a rondelle in front of the axle. The form of the cheeks is peculiar, 

 presenting- no salient angles, and so rounded as to each receive a strap 

 extending entirely around it and the axle. By means of a nut arranged as 

 represented, and aided by bolts and corresponding nuts, this strap may be 

 taken up, as the wood which it incloses shrinks, and may be caused 

 to maintain a tight condition upon the cheeks at all times. 



It was at first objected that the trail of my carriage was too low, and 

 liable to come in contact with stumps or obstructions on bad roads; this 

 objection did hold to some extent as against the 12-pounder carriage which 

 I at first offered, but it will be observed, by examining the carriage " lim- 

 bered up," that the forward end of the trail is nearest the ground, and at 

 that point it is higher than that of any standard United States field car- 

 riage. In addition, I have now placed the implements on the top of the 

 trail, while in the standard carriage they are below, giTing. this carriage 

 an advantage on that account. In this carriage the elevating screw never 

 projects below the trail to strike an obstruction — another advantage. 



In gun carriages, as ordinarily constructed, the violent recoil of the gun 

 tends to twist off the fastenings, which are all on the top of the axle, by 

 which the axis is secured. In this construction, there is no such tendency. 



The trail is of the usual form, except where it rests upon the ground. 

 The ordinary trail is rounded at this latter point, so as to form a portion 

 of a cylinder, with the axis at right angles to the plane of the trail. Such 

 form allowed only a small surface of the trail to rest upon the ground, and 

 the pressure thereon at the instant of recoil was so great as to cause it to 

 dig into the ground and partially bury itself therein. While this action 

 diminished the amount of the recoil, and was so far an advantage, it so 

 altered the condition of the ground on which it rested and moved that 

 another shot could not be fired from the same position, without a readjust- 

 ment of the elevation of the gun, and also of the trail, which would some- 

 times slip, after the gun was carefully sighted. In this improved carriage 

 I form a plane surface under the trail, where' it rests upon the ground, 

 which surface is gradually rounded into the inclined surface of the trail, as 

 shown. This plane portion presents so broad a surface to the ground on 

 which it rests as to prevent the trail from digging a hole in the ground, 

 and to avoid the consequent necessity of a frequent change in the 

 position of the carriage, or a corresponding change in the elevation 

 of the gun, relatively to the carriage. This feature is of great importance 

 in carriages constructed to admit of so great an elevation as my improved 

 form, for the strain on the carriage is greatly increased at such elevations, 

 and would be liable to break the carriage, unless it were at liberty to recoil 

 readily. And if the trail was so pressed into the earth as to seriously 

 retard the recoil, the liability of damage to the carriage would be greatly 

 increased. 



To the flat surface I affix a flange or keel, as shown by the small cross 

 section. This is a narrow and sharp piece of metal, adapted to cut into 

 the earth and act as a keel to cause the recoil to be in a straight line; if 

 there is an obstruction behind one wheel the shot may be diverted slightly 

 by the slewing of the carriage. 



