4*2 VELOCITY OF PROJECTILES. 



DwHutton with Fifteen years after this Dr. Hutton made many experiments 

 cannon balls. at Woolwich with cannon balls by means of the pendulum. 

 Count Rum- About the year 1778, Count Rumford improved this me- 



furd s improve- ^^j ^ ( r \ a ] f anc i invented a very fimple method of fufpending 

 the gun-barrel fo that the recoil took place without the axis 

 Chafing to be horizontal. 

 Dr. Hutton's Laftly, Dr. Hutton refumcd the fubject, and made a number 



"oft complete ^experiments from 1783 to 1786, with much care, and at 

 onthefubjed. great expenfe, on both kinds of pendulum. Thefe may be 

 confidered as forming the fnofl complete and inftru&ive treatife 

 we i)3ve on experimental balliftics. 

 Antonys de- We have not mentioned the labours of Antoni, but we muft 



fcnption ot ■ z- m)t j )a f s over a mac i,j ne Jofci ibed by him in his effay on gun- 

 j)ovvdor. This, which he fays was invented by a mechanic 

 named Mathey, con lifts of a horizontal circle, the centre of 

 which is fupported by the fuperior extremity of a vertical axis, 

 and ferves as a bafe to a cylindrical envelope of paper. A 

 rotatory motion is given to this cylinder by means of a cord 

 palling over a leading pulley ; and the projectile being dis- 

 charged horizontally, when the angular velocity of the machine 

 is uniform, in a vertical plane in which the axis is found, pierces 

 the cylinder in two points, the di fiance of the fecond of which 

 from the diameter palling through the firft meafures the 

 arc defcribed by the machine during the paflage of the pro- 

 jectile. 



Col. Grobcrt's The machine recently invented by Col. Grobert is con- 

 newly invented fl ru(5led as f U 0WS . 

 machine de- . 

 fcribed. A horizontal rotatory axis about 34 dec. ( 1 1 feet) long carries 



Itconfiftsoftwoat each extremity a pafteboard dilk perpendicular to it, and 



pafteboard <«*» f a ft ene< i to j t f t hat the whole may turn rapidly without de- 

 volving fwirtly . \ r J 

 at the exrremi- ranging the reipective po/itions or the parts, 

 ties of an hori- j± ro tatory motion is given to the two difks by means of a 

 weight fufpended to the end of a cord, which, after having 

 patTed over a pulley ten or twelve yards from the ground, is 

 rolled upon a wheel and axle level with the clifks. An end- 

 lefs chain, paffing round the wheel and the rotatory axis of the 

 difks, communicates to this axis the motion which the weight 

 in its defcent imparts to the wheel. 



The advantages this machine poflefles over Mathey's confift 

 in the horizontal petition of its axis, which admits the ufmoft 

 degree of firmnefs and regu'arity in the pofilion and motion of 



the 



