OKOGRAPMICAL AND fOPO<3R APFTIC A L IMPROVEMEJTTS. ^05 



water-works may be ere6ted ; where navigable canals may be 

 cut; and where high-ways and rail-roa-ds may be laid out on 

 the beft and moft level ground. 



4lhly. The fubterraneous treafures of the mineral and foflii — and mkw 

 kingdoms are generally found in ftrata; and if they are not 

 truly horizontal, they make a certain angle with the horizon, 

 A map on this projection may enable the mineralogift to follow 

 any one ftratum, at places even far diftant from each other. 



Problem, 



To find the true declivity of any piece of ground, in any map Examples corn- 

 laid down on the principles of the prefent plan. ^"^^ * 



Example \Ji. for D. fee Plate IV. 



As the perpendicular height, -4 feet - - 60206 

 Is to radius, 90* - - *. lO.OOOOO 



So is the horizontal diilance, 4 feet - 60206 



10.60206 

 To the co-tangent of the deelivifyi 4.5** - 10.00000 



Example Q:d. for B. ' 



Asjhe perpendicular iieight, 4 feet - - 60206 



Is to radius, 90" - - - lO.OOOOQ 



So is the horizontal diftance, S feet - 90309 



10.90309 

 To the co-tangent of the declivity, 26^ 34' 10.30103 



Example Sd. for C. 



As the perpendicular height, 4 feet - - 60206 



is to radius, 90^^ - . . lO.COOOO 



So is the horizontal diftance, 18 kct 1 .25527 



11.^5527 

 To ihe co-tangent of the declivity, 12^ 32^ 10.65321 



The annexed furvey, Plate IX. of a fmall lake and artificial A furvcy ac- 

 mountain in the garden of his Excellency Count de Strogonotl', method.*'^ ^ " 

 near St. Petcrfburgh, has been doled by the tables of the dif- 

 ference of latitude and departure, as follows ; 



N 30 E- 



