Chap. 3.] Phenomena of convex Mirror >. 193 



convex mirror a b j the two rays C e and D d> which 

 proceed from the extremities of the- objed, and which, 

 without the interpolation of the mirror, would converge 

 at/, are refleded lefs convergent, and unite at i t form- 

 ing an angle much more acute than they would other- 

 wife have done. The confequence, therefore, of the 

 vifual angle being fo much more acute is, that the 

 image g b is proportionably fmaller than the objed it- 

 felf. 



The fecond effed of this difperfion t>f the rays isj 

 that the image appears at a lefs diftance behind the 

 glafs than it would have done in a plane mirror. To 

 underftand this effect, it is necefiary again to advert 

 to a principle of optics, which has been juft dated, viz. 

 that objects are rendered vifible not by a fingle ray of 

 light proceeding from every point of the objed, but that 

 from every minute point of the furface of every vifi- 

 ble objed pencils of divergent rays proceed, which are 

 <again converged on the retina of the fpedator's eye. 



Suppofe then G (fig. 4.) a luminous point of 

 any vifible objed, from which a pencil of diver- 

 gent rays proceed, and fall upon the convex mir- 

 ror a b. Thefe rays, agreeably to the nature of thefe 

 mirrors, are reflected more divergent, and have their 

 fiditious point of re-union (or virtual focus) g much 

 nearer to the eye and to the furface of the mirror than 

 they would otherwife have. The image, therefore, as 

 may be feen in the figure, inftead of being at a dif- 

 tance behind the mirror equal to the diftance at which 

 the objed ftands before it (as would be the cafe in a 

 plane mirror) will appear at a fmaller diftance, and 

 this diftance will always be diminifhed in proportion 

 to the convexity of the mirror. 



For the fame reafons an objed of a certain fize, 

 placed either perpendicularly or obliquely before a 



VOL. I. Q convex 



