The PraBlce 



Part IL 



the Side where you would make your Leveling. Then 

 =take Water, which you may mix with a little Claret Vine- 



ther, and fill the Pipe, fo that the Water coming up into 

 the three Vials, there may remain a little Vacancy at Top* 

 Let the Inftrument reft till the Water has done floating, and 

 be careful to cover the Mouths of the Vials with Paper, left 

 ^the Wind Ikould caufe any Agitation of the Water. Then 

 take a long Pole, upon the End of which is fixed a very 

 fquare Piece of white Paftboard, and caufe a Man to hold it 

 at fomeDiftance from the Level, asatD, making him raife 

 or lower it, till the Top of the Paftboard be exactly in the 

 'Line of Aim H, which is directed in this Manner. Placing 

 yourfelf at fome Diftance from the Level, fet your Eye, and 

 bourn by the Surface of the Liquor contained in the three 

 Vials, which will guide your Vifual-Ray, according to 

 which you adjuft the Pole to its right Height. This done, 

 take the Height from the Superficies of the Water in the Re- 

 ferver to the Liquor contained in the Vials, and mark 

 it downwards upon the Pole, the Length of which is to be 

 reckoned only from this Mark, to the Level of the Place 

 where it is fixed. You fhould have a Paper, upon which to 

 fet down thisfirft Station of your Leveling, and the others 

 -that follow. Let the Pole be removed, and at D, where 

 the Foot of it flood, fet the Level, and fix it as you did be- 

 fore, for a fecond Operation ^ and fo by feveral Stations, 

 from D to E, from E to F, and from F to G, you come to 

 the Place Q where the Spouting Fountain is to be. Then 



-caft 



