^68 E»ptrimen1i on GunpoLudif. — Dama'rus Steel. 



The T.iblf , in tlie original, conuins a great number of experiments, in wliich the weight or 

 piece of ordnance was cither not raifed, or was thrown up with a loud report. Thofe expe- 

 riments, in which the weight jull morcd without a report, are obvioufly fuch as indicate the 

 elaftic force to have been equal to the prellurc. I have accordingly felefted tl cfe only in 

 the following table as fuitable to form tlic bafis of computations. The day, hour, and mi- 

 nute when each experiment was made, are likewife to be found in the original, though it did 

 not fceni neceffary to infert them in this abridgment. The exprelTion of the weij^lit on 

 atmofphcres is grounded on the aflumption, that the mean preflure of the atmofpherfti* 

 equal to fifteen pounds .ivoirdupois upon a fquare i;ich. 



TABLE I. — Experiments on ike Force of Fired Giinpo-wdcr. 



In the laft experiment, with near eleven thoufand atmofpheres, the weight was raifed' 

 with a very fharp report, louder than that of a well- loaded muHcet ; and in the experiment 

 immediately following with the fame charge, but with the addition of fix hundred and nine- 

 teen pounds to the weight, the vent-tube of the barHel burft. This experiment was the 

 t5th of the Table, probably the 85th time of heating the tube. 

 (To be concluded in the next Number.) 



VII. 



Obfervntions and Experiments on Steel, refembling that of Damafcus ; -with an eafy Tejl for dt- 

 termining the uniform ^aliiy of Steel before it is employed in Jf^orks of Delicacy or Expence. 



In the infancy of fociety the hardeft bodies, fuch as (tones, and certain kinds of wood, 

 were felefted and ufed for cutting inftruments, and ftill are applied to that purpofe in fe- 

 veral parts of the world. Thefe materials were fucceeded by copper, hardened by a mixture 

 of tin, of which numerous weapons yet remain in the cabinets of the curious. And laftly, 



fteel, 



