two and four-wheeled Carriages. 36$. 



flop 30. That is, let there be a fingle excavation in a road 

 coniilting of inch dry fetid; fet the carriage be in F ; and let 

 the. angle y ~ 19°, MI ■ ■-- 9 inches, ()!---- 12. feet; in this, 

 cafe, fin. k 0x6250, and * — %*$$''•> coniequently OH[ 

 --0-38038, and £ = 0-03170. From thefe data we mall 

 have, 



For four -wheeled Carriages. 



I- A A P COS. (* + y) -. • 12*273 



' nxV cos. a =9*975 



(' P -h />) fin. (a + y) = 26yi6o 



(; P + f>') fin. a — 49*5 27 



(■I P + />) cos. (a -f- 7) fin. j3, tang. I = 115*624 



(2 P + />') cos « «> *»*■• ft ^ng. -1 = 107*112 



R= 561*77^ 



P07* twQ'wbeeled Carriages. 

 jaxP cos. .(« -f 7) = 15*780 



(1> + e p + w ) f m . (« 4. y) = 535*3I7 



'(P -H si ) cos. (*« 4- y) fin. £, tang. 3 = 208*035 



H' - 759'**3* 



We have here M fx — -^- J cos. 7 = 561*772, and M 



(I — T") 2 cos * 7 — 759* J 3 2 5 confequently or = -f 1*518 



and glfe — 001 87, if we make M - 800 and G = 1 1, as 

 in fe&ion 30. Thefe two horfes, therefore, would not be 

 able to draw a two-wheeled carriage over the point F of this 

 excavation; whereas they could draw without much exer- 

 tion, and with a velocity of more than 18 inches per iecond, 

 a four-wheeled carriage over the fame point. On the other 

 hand, they would be obliged to employ- nearly as great an 

 exertion tor the hind- wheels; but this double exertion will 

 be lefs fatiguing than the fingle exertion in the cafe of two 

 wheels provided they do notliick fait, as the calculation fup- 

 pofes. 



III. Shigle Elevation** 



Seel ion 38. 



Fig. 9. The cafe is the fame when the obfiaeles v, 

 occur are fingie elevations, fueh as ridges, (tones, broken 

 pavement, and bridges, ike. Let G be an obftacie of this kin Jj 

 the height of which is ER = b-, let the femidiamcier of tht 



\\J 



