go Obfervafio XI. 



liinc inferaturt i ) C AS : CS =CS A : AC = diftantia A afpeculo 



2) CBS : CS-CSB : CB ■= diftmtia B afpeculo 



3) CBS : CS = BCS : BS = diftantia oculi a B. 



4) CAS : CS = ACS : AS — diftuntia oculi ab A. 

 faventis ita, anguio ACB, quoniam RCS + RCS + BCS + 

 ACB=duobusre&is,quorum tribus cogmtis, quartusinno- 

 tefcit, tum et lateribus AC et CB, diltantia B ab A haud 

 poterit defiderari: nam trigonometrice 



ut fumma laterum ad different, laterum, fic tang 4 \ fumm, 

 LL incognit, ad tang* * different, LL incognit, Tac- 

 quet Probl. X. 

 hinc in aBAC 



BAC:CB = ACB: AB 

 Eodem modo diftantia Wa B vel A, C et S inveftigare licet, 

 quoniam anguli ACW, BCW, CSW, ASW, WCS, 

 VPSB, tum et latus CS funt commenfurabilia etc, QJiL.F, 



Problema III. 



Diftantiam Obiefti dire&e invifibilis, verticaliter fupra 

 ftationem unicam datam , radiantis in ipeculum planum, 

 «ius adminiculo, metare? 



Refolutio- 



Sit obie&umO (Tab.U. Fig. 4,) fupra verticem fpecula- 

 toris perpendiculariter elevatum , et non nifi per reflexio- 

 nem in C mediante fpeculo plano oblique inclinato vifibile, 

 xjuodque baculo horizontaliter extenfo, angulo fpeculi co- 

 gnito, teneat homo, qui fuam propriam dimenfionem SP 

 ctfciat, -oportet* 



Sit radius reflexus AS cum horizontc ut et cum brachio 

 cxtenib, parallelus, angulus RCS datus eft, hinc Angulus re- 

 flexionis OCS invenire licet, eft vero CSO Angulus reftus, 

 quare COS : CS = OCS: OS. 



Proble- 



