27f CONDfiNSER OF FORCES. 



Solution cxhi- I (hall here apply the folution which I have dlfcovercd of 

 bked in an en- ^j^jj problem, to the dynamic effba of wind ; it will be eafy 

 to make the fame general when the other firft movers are ufed. 

 Problem in dy- The fe6lion and plan of the machine are exhibited in Plates 

 pofe aVonftan°^" ■^^* ^^^ XVI. O O reprefents the vertical arbor to which 

 weighttoava- windmill fails are adapted; eeee is an aflamblage of carpen- 

 m^ver^'^and ^'^' °^ which one of the radii O e, bears a curved piece h d, 

 tranfmit the of iron or fteel : Vertical axes of rotation a a a, being placed 

 force, &c. round the axis O O, alfo divide the circumference in which 

 Ihey are found into equal parts. 



Each of thefe axes carries a curve af, of iron, fteel, or 

 copper; fo fituated, that when the wind a£ts upon the fails, 

 the curve b d preffes againft one of the curves af, and caufes 

 the vertical axis to which this laft curve is fixed, to make a 

 portion of a revolution. 



The curves b d and af muft be fo difpofed, that when b d 

 ceafes to prefs on one of the curves af, it (hall "at the fame 

 fj ^}^^^^^ begin to a6l upon the following curve : the number of 

 axes which are provided with thefe curves, muft be deter- 

 mined by the particular circumftances of each cafe ; and it 

 is alfo pradicable to fubrtitute, inftead of b d, a portion of a 

 toothed wheel having its centre in the axis O O, and to place 

 portions of pinions inftead of the curves af, but the difpofl- 

 tions reprefented in the figure are preferable. 



Each of the axes aaaa (which are all fitted up alike, 

 though, for the fake of clearnefs, only one of them has its 

 apparatus reprefented in the drawing), each of thefe carries 

 a drum or pulley tt rVy on which is wound a cord that palfes 

 over a pulley p, and ferves to fupport a weight Q by means 

 * ^ of the lever F G, upon which this weight may be Aided and 

 faftened at different difiances from the point of motion G. 



The fame axes a a pafs through the pinions q q, to which 

 they are not fixed ; but thefe pinions carry clicks or ratchetts, 

 which bear againft the teeth rr; fo that, when the weight Q 

 tends to rife, the ratchett gives way, and no other effect is 

 produced on the pinion qq, either by the motion of the axis 

 or of the drum t trr, excepting that which caufes the afcent 

 of the weight </.g,. But the infiant that the curve or tooth b d 

 ceafes to bear againfl: one of the curves af after having 

 caufed the correfponding weight Q to rife, that weight Q 

 tends to redefcend, and then the toothed wheel r r acts againft 



the 



