OP GUN-POWDER. 43

102. It results from these experiments, that the chargesthat give the longest ranges when cannon are fired at thehighest elevation their carriages will admit of, are greaterthan those which produce the same effect when fired hori-zontally (8y). But the ranges do not increase in the regu-lar progression that might be expected. For instance, inthe sixteen pounder,’ the charges of 5 lb. 12 oz. and 7 Ib.3 oz. gave ranges nearly equal, while 61 b. 9 oz. gave onemuch longer. These irregularities proceed from the diffe-rent charges not having been fired on the fame day; theZ lb. 12 oz. were fired the 23d of March, the 61 b. 9 oz.the day following, and the 7 lb. 3 oz. on the ist of April;if they had been fired on the fame morning, the modifica-tions in the explosion of the powder, and the air’s resistanceto the shot, resulting from the alterations in the state of theatmosphere, would have been avoided : in the 4th and 5thchapters of the second part, this matter will be more fullydiscussed.

On repeating these experiments with such precautions asto avoid the modifications arising from changes in the stateof the atmosphere, the charges (ioi)that give the longestranges will be found to be almost double of those used in1746; but the increase of range is of little importance com-pared to the increase of the recoil, and the greater shocksustained by the carriage j these large charges should never beused for common service.

103. In experiments of this kind, a remarkable inequa-lity between two ranges from equal charges of powder willoccasionally occur, though every precaution be taken to firethem under circumstances as nearly similar as possible.These inequalities were neither so frequent nor conside-rable in 1746 as in 1750; but it is impossible totally toavoid them, for supposing the direction of the guns to remainunaltered at the explosion, yet there are two causes whichseparately or conjointly may render the ranges from equalcharges of powder unequal.

i* The shot in passing through the plane of the gun,may not exactly follow the direction of the bore; or onquitting the gun, it may take a different direction.

104. 2. The powder may not be equally well collectedin the piece, so that charges though equal in quantity,have not the same figure: large charges are more liableto this accident than smaller ones, particularly when

rammed