532 



Mechanical Science. 



[Nov. 



and Lieutenant-Colonel Forrest, extracted from a lithographed circular, published 

 by the Honorable Court, dated October 19, 1831. 



Wheels tried. 



Size. 



Height and Width 

 of Tire. 



Nature of Gun and Car- 

 riage. 



Remarks. 



Height, 5 feet,- 



24 or 18 pdr.- 



12 or 6 pdr. 



Width of Tire, 6 in. 

 Height, 5 feet,— — . 



Width of Tire, 3 in, 



24 pdr. Iron, 



cwt. qr. lbs. 



Weight, 50 1 25 



Ditto of Carriage, 

 12 pdr. Brass, ~- 



8 lbs. 



The distance of the 

 Guns from the Butt 

 was about 35 yards. 



{ 



cwt. qr. lbs. 



Weight, — - 18 5 



Ditto of Carriage, 



The experiments commenced with an iron 24-pounder gun and a brass 12-pounder, 

 mounted on travelling field carriages, and their limbers : to the 24-pounder carri- 

 age was fitted a pair of the patent wrought iron wheels ; to the limber, their 

 own wood wheels were used. 



The 12-pounder was equipped in the same manner, and provided with a draft of four 

 horses. The 24-pounder with 6. Thus prepared, both were trotted at a brisk pace, 

 and sometimes gallopped along a very rough pavement for about an hour ; the wheels 

 could not have been submitted to trial of strength more severe, some of the hol- 

 lows in this pavement caused the carriages to bound from stone to stone to the 

 extent of some feet, and the violence was so great as to break the rope lashings 

 used to keep the guns in their places on their carriages, and the 12-pounder 

 carriage was jerked completely off its limber. i 



On examination of the iron wheels after this trial, without removing them from 

 the axle, no mark of injury was perceptible, nor a joint started : the wheels of the 

 limbers which were wood did not resist the shaking so well, although they had 

 only the weight of the empty limber boxes to carry ; several spokes were started 

 more or less from their sockets, one of the openings measured 3-16ths of an inch 

 in width. — It maybe observed, these were wheels never before used, and as they had 

 lain several years in store, it is less to be wondered at that the wood had shrunk 

 from the original joinings. 



The next experiment was to drag the 24-pounder through marshy ground, with a 

 weight altogether of from 4 to 5 tons, of which the limber wheels had comparatively 

 nothing to carry, say about a 20th part of the weight. — It was started with a 

 draft of six horses, but the weight sunk too deep for that number to drag it out, 

 and the horses were sinking up to their knees ; two more were then added, but 

 while stopping the wheels of the carriage had sunk to a depth of 14 inches, and 

 it required the exertions of half a dozen men in addition to set it in motion. 



This experiment ought to have been begun with 10 horses, at least eight is the 

 proper number allowed by the Regulations of H. M. service, for a 12-pounder 

 weighing about 18 cwt. — It was therefore not to be expected, that the same number 

 should drag through such a marsh, a load of 50-cwt. exclusive of the weight of the 

 carriage. 



This trial was not quite as conclusive as could have been desired, yet it was 

 evident, that had the proper number of horses been given in the outset, the iron 

 wheels would have cut their way through the swamp without a halt, but whether 



with the same ease as a wooden wheel, remains to be tried. The 6-inch rim 



iron wheel has a tenden cy to sink into and plough up the soft ground, which ad- 

 heres to the inner part of the rim, and accumulates, an additional weight being 

 thus added to the wheel. — It is however to be remarked, that this objection ap- 

 plies only in very soft ground. 



