170 of Terrace-Walks, 



Hill, at A, at the Top, or, more properly, 

 at the Bottom of the Perpendicular, at A to B^ 

 is 182 Foot. 



Now, in order to take a general View of 

 it in Numbers, we muft examine what Pro- 

 portion the Height of the Hill bears with the 

 horizontal Bafe, fince 'tis this that muft deter- 

 mine whether you are to divide your Hills by 

 Walls or by Slopes, or, which is a middle 

 Way, by Walls and Slopes mix'd, viz. one 

 Wall and Terrace, with a Slope between that 

 Wail and the next, as you may fee in Figure 

 the 9th, Plate the 27th. In order then to 

 cftablilh what I am going to lay down for our 

 Diredron in this Cafe, we ought never to 

 make the Perpendicular of our Slopes above 15 

 Foot in the higheft and moft fteep Hill 5 

 and the Bafe to that Perpendicular ought by 

 f}o means to belefs than twice the Perpendi- 

 cular, &c. It will therefore follow from 

 thence, that v/here-ever the Horizontal of a 

 Hill be not above twice the Perpendicular, 

 that there the Hill muft of Neceflity be fup- 

 ported by Terrace- Walls, or Terrace- Walls 

 and Slopes mix'd together 5 but where it is 

 more, that it may be done by Slopes, or by a 

 a Wall and Slope, as has been already men- 

 tioned. 



To put what we have been advancing in- 

 to Praftice, the Perpendicular of the Hill be- 

 ing 49 Foot, multiply this 49 by 2, and the 

 Produd is 98 Foot 5 and fo much is required 

 for the Horizontal of all thefe Slope?. This 



98 



