26 Scientific Proceedings, Royal Dublin Society. 



as the sixth^ power of the velocity when this lies between 900 and 

 1100 f. s. ; to vary as the third power from 1100 to 1350 f. s. ; 

 and for velocities above 1350, to vary as the second power, which 

 is the Newtonian law, based on the supposition that the shot is at 

 every moment penetrating an undisturbed medium, a supposition 

 which only holds for velocities greater than the velocity of sound. 

 This remarkable change in the law of resistance, when the ve- 

 locity passes a certain limit, was early discovered by Robins and 

 Hutton. Under these circumstances Mr. Bashforth has chosen to 

 express the resistance of the air by the help of a variable coefficient 

 and the third power of the velocity ; and as it has been found that 

 the effect of the resistance at a uniform velocity varies as the 

 square of the diameter divided by the weight, it is easy to apply 

 the Tables to shot of various dimensions by substituting the parti- 

 cular value of ■:=. in each case. 

 yy 



As the experiments with the Bashforth Chronograph were 

 carried out with guns varying from 3 inches to 9 inches diameter, 

 and with shot varying from 6 lbs. to 250 lbs. weight, their appli- 

 cation to small arms must be taken as an approximation only, 

 since there are in the latter case modifying conditions, the effects 

 of which cannot be predicted. 



In the case of spherical shot, however, as experiments made 

 with musket bullets have been found to give results which apply 

 to large guns, it is fair to conclude that the Tables calculated from " 

 the latter may, with sufficient truth, be applied to spherical projec- 

 tiles of diameters much smaller than musket balls, such as the 

 small shot used in fowling-pieces ; and it is more particularly to 

 the movement of such small projectiles that I wish to direct 

 attention. 



In 1878, Mr. J. H. Walsh, the ingenious editor of the Field 

 newspaper, dissatisfied with the tests then in use, devised a kind of 

 recoiling target, which he named a " force gauge," for the purpose 

 of measuring the force with which the pellets in a charge of shot 

 struck the mark at a certain distance. Up to that time very vague 

 ideas were held as to the actual velocity of the charge propelled 

 from shot guns. One writer in the Field placed it as low as 



1 This statement is modified subsequently. See Final Report, p. 4. 



