104 FERGUSON'S LECTURES. 



If there be some advantage from small fore-wheels, 

 on account of the carriage turning more easily and short 

 than it can be made to do when they are large ; there is 

 at least as great a disadvantage attending them, which is, 

 that as their axle is below the level of the horses' breasts, 

 the horses not only have the loaded carriage to draw 

 along, but also part of its weight to bear ; which 

 tires them sooner, and makes theni grow much stiffer 

 in their hams, than they would be if they drew on a 

 level with the fore axle. And for this reason, we find 

 coach horses soon become unfit for riding. So that 

 on all accounts it is plain, that the fore-wheels of all 

 carriages ought to be so high, as to have their axles 

 even with the breasts of the horses ; which would not 

 only give the horses a fair draught, but likewise cause 

 the machine to be drawn by a less degree of power. 



We shall conclude this Lecture with a description of 

 Mr. Vauloue's curious engine, which was made use of 

 for driving the piles of Westminster-bridge : and the 

 reader may cast his eyes upon the first and second 

 figures of Plate I, in which the same letters of reference 

 are annexed to the same parts, in order to explain those 

 in the second, which are either partly or wholly hid in 

 the first. 



-4 is the great upright shaft or axle, on which are the 

 great wheel B and drum C, turned by horses joined to 

 the bars S, S. The wheel B turns the trundle X, on the 

 top of whose axis is the fly 0, which serves to regulate 

 the motion, and also to act against the horses, and keep 

 them from falling when the heavy ram Q is discharged 

 to drive the pile P down into the mud in the bottom of 

 the river. The drum C is loose upon the shaft A, 

 but is locked to the wheel B by the bolt F. On 

 this drum the great rope H H is wound ; one end of 

 the rope being fixed to the drum, and the other to the 

 follower G, to which it is conveyed over the pulleys / 

 and K. In the follower G is contained the tongs JF(see 



