72 



THE CABINET OF NATURAL HISTORY 



have not taken the pains of making the experiment; 

 although sufficiently apparent from its hardness, &c. 



I enclose the article in the Journal, to which I have 

 alluded, and will forward the specimen with this, the first 

 convenient opportunity. 



Very respectfully, 5'our obd't servant, 



A. W. FOSTER. 



The following is attached to the specimen now in the 

 Philadelphia Museum: — " Petrification of Wood. — This 

 piece of petrified wood, was broken from the stump of a 

 tree measuring fifteen feet in circumference, and about four 

 feet in height by actual measurement. It was found on 

 the S. W. bank of the Missouri River, about thirty miles 

 below the mouth of the Yellow Stone, and nearly opposite 

 the junction of White Earth River with the Missouri, in 

 lat. about 48° 15'." 



The most remarkable facts, concerning the petrifac- 

 tions of this region, are, that stumps, limbs and roots 

 of trees of all sizes, broken into fragments, lie scattered 

 over the country for a distance of thirty or forty miles, at 

 an elevation above the level of the river, of at least five 

 hundred feet, and at a point which is computed at six or 

 seven thousand feet above the level of the Ocean. 



Surgeon Gale, of the Army, who, as well as myself, 

 was attached to the military expedition that ascended the 

 Missouri in 1825, from Council Bluffs to Two Thousand 

 Mile Creek, and who accompanied me on an exploring 

 and hunting excursion, across the country, from below the 

 mouth of White Earth River, to the Yellow Stone, as- 

 sisted in examining and measuring the stumps of some of 

 those petrified trees, and he gave it as his opinion, that 

 from the appearance of the country, some thousand years 

 must have elapsed since a thick forest of timber stood 

 where now nothing remains but these petrified fragments. 



He was rather inclined to the opinion, that the kind of 

 wood, was the cotton wood of the Missouri country, com- 

 mon enough along the banks of the Missouri river and its 

 tributaries. 



This subject furnishes abundant matter for the natural 

 philosopher, for whose curiosity and speculation it is here 

 submitted. G. H. CROSMAN, 



U. S. Army. 



DEFENCE OF THE PERCUSSION. 



The general opinion is, that shot is propelled to a greater 

 distance and with more uniform velocity from a gun, in 

 proportion as the force of powder exceeds the weiglit of 

 shot; and it is upon this false supposition that the anti-per- 

 cussionists have grounded their objections to detonating 



guns, by affirming, that "the explosion takes place so in- 

 stantaneously that the whole of the load of powder is not 

 ignited, and that a portion is driven out unexploded." 



It is well known that the resistance which bodies meet 

 with in passing through a fluid, increases as the square of 

 their velocity. Therefore, a load of shot, passing through 

 the air at a given rate, would meet with four times the re- 

 sistance if its speed were doubled. lience, if one drachm 

 of powder will carry a load of shot forty yards with a given 

 force, the power of two drachms would, it is true, give a 

 double velocity to the shot at its egress from the muzzle of 

 the gun; but the resistance being now four times greater 

 than in the former instance, the force of it at the distance 

 of forty yards would be very much diminished. 



I have shot three seasons with my present gun, which is 

 a double-barrelled detonator. For the two first seasons I 

 used the proportions for the load which I received from 

 the gunmaker, and during that time I do not recollect to 

 have killed a bird farther than forty paces. Thinking this 

 might be improved upon, I determined to try the effect of 

 reducing the quantity of powder; and having first loaded 

 with the original charge (and No. 5 shot), I fired at a tin 

 powder flask at the distance of forty measured yards, and 

 struck it with five shots, but the marks were barely per- 

 ceptible. I then reduced tlie quantity of powder (only) 

 one quarter, and the shots made much deeper indentations 

 in the tin than before. I then reduced the powder still 

 further, to about two-thirds of the original charge, and the 

 result answered my expectations fully: for I found five 

 shots as firmly set in the tin as stone was ever set in gold. 

 I measured the distance of two shots at birds: one was 

 sixty-two paces, and the other sixty-three; in both instances 

 the birds fell dead at the fire. 



I have from the first maintained that a detonator ignites 

 more grains of powder than a flint and steel gun does. 

 The result of my experiment has fully established my opin- 

 ion upon this point. The fire from the copper cap being 

 driven with considerable force into the load of powder, ig- 

 nites the whole; the force of which explosion being too 

 great for the weight of shot, diminishes at a certain distance 

 the velocity of the latter. 



On the other hand, the fire communicates with the pow- 

 der in the barrel of a flint and steel gun merely by the igni- 

 tion of grain by grain; so that just as much of the powder, 

 and no more, explodes as is sufficient to discharge the load. 



A proper regulation of the charge, therefore, seems alone 

 requisite to make a detonator carry as strong as a flint and 

 steel gun; and if the means for diminishing the force of 

 the powder instead of increasing it, had been consulted, 

 less time would have produced a more satisfactory result. 



Sporting Magazine. 



