G UN FO W DER . 1 99 



claim neither attention nor belief. Thus some will 

 have it, that gunpowder produces the greatest effects 

 in the morning and evening, when the air is cool and 

 dense ; whilst others assert that its force is greatest in 

 sunshine, and during the heat of the day. Mr. Ro- 

 bins concludes, from the result of several hundred 

 trials made by him at all times of the day, and in 

 every season of the year, that the density of the atmo- 

 sphere has no effect in this matter, and that we ought 

 to attribute the variations, observed at these times, to 

 some other cause than the state of the air: probably 

 they are owing to the imperfection of the instrument, 

 or to the manner in which the trial was conducted. 

 In this state of uncertainty, then, upon the theory of 

 the effects of gunpowder, we remain at this day. 



If experiments, however, are made with the prover, 

 great care must be taken not to press the powder in 

 the smallest degree into the tube, but to. pour it 

 gently in ; and, particularly in trying the strength of 

 different powders (which is the best use to which the 

 instrument, imperfect as it is, can be applied) atten- 

 tion must be paid that one powder is not pressed 

 closer than another at each experiment, nor the suc- 

 cessive experiments made until the prover is perfectly 

 cool, otherwise no comparative certainty can be 

 gained. By far the most certain method, however, 

 of determining the quality of, powder is, by drying 

 some of it very well, and then trying how many sheets 

 of paper it will drive the shot through at the dis- 

 tance of ten or twelve yards. In this trial, care must 



