Jdditional Notes, 457 



Mr. Robins, however, in estimating the meclianlcal force 

 of Guripo'iVder, iell into an error, which has been since cor- 

 rected by our acute and persevering countryman, Count Rum- 

 ford. The former states this force, according to liis ex- 

 periments, to be 1 000 times greater than the mean pressure 

 of the atmosphere; while the celebrated Daniel Bernoulli 

 determined it to be not less than 10,000 times greater. Such 

 a difference of opinion led Count Rum ford to pursue a 

 course of experiments, of whicli some were published in the 

 Philosophical Trajisactions for 17S1, and the remainder ia 

 the 'rrunsaciioiis of the same Society for 1797; with the 

 view principally of determining the initial expansive force of 

 Gunpowder. By one of these experiments it appeared that, 

 calculating even on Mr. Robins' own principles, the force 

 of Gunpowder, instead of being 1000 times, must at least 

 be 1308 times greater than the mean pressure of the at- 

 mosphere. From this experiment the Count thought him- 

 self warranted in concluding, that the principles assumed by 

 Mr. Robins were erroneous, and that his mode of ascer- 

 taining the force of Gunpowder could never satisfactorily de- 

 termine it. Despairing of success in that way, he resolved 

 to make an attempt for ascertaining this force by actual mea- 

 surement; and, after many unsuccessful experiments, he was 

 at length led to conclude that this force was at least 50,000 

 times greater than the mean pressure of the atmosphere. — ' 

 See R u M F R D '5 P/i ilosoph iced Essays^ S v o. 



M}\ Benjamin Thompson (nozv Count Rumford). p. 37. 



This great practical Pliilosopher was born, about the year 

 1753, at Woburn, a small town in Massachusetts, ten mile» 

 north' of Boston. His parents were in humble life, and his« 

 advantages, with respect to education, were small. But lie 

 was early distinguished as a lad of spirit and enterprise, and 

 discovered a fondness for knowledge. After spending some 

 time in a retail store in Boston, wiiere he was more fond of 

 amusing himself with a violin than of attending on cus- 

 tomers, and preferred making experiments with an electrical 

 vmchint to either, he returned to Woburn : here, however, 

 lie did not remain long. In 177 '2 he attended Professor Win- 

 THROP's Lectures on Experimental Philosophy, in Harvard 

 College. He was not a matriculated student, but, being re- 

 garded as an ingenious and promising young man, was par- 



3N 



