ERRATA. 
PART I. 
P. 143, 1 . 3, for affraiant, read effraiant. 
Note from Henry Brougham, Jun. Esq. author of the paper on the inflection, re- 
flection, and colou; • of light. See page 227, §cc. 
“ Owing to an error which crept into the integral calculus by which the problems on 
“ the trajectory of light were resolved, two of these solutions are erroneous, and must be 
“ corrected thus : 1 . When the bending force is inversely as the distance, the curves to be 
“ squared are, a conic hyperbola, and a logarithmic, y*— • The trajectory, there- 
“ fore, cannot be found in finite terms ; its equation is y* l ~ = ** ; and the sub- 
** tangent is to the subnormal as 1 to /— . 2. When the bending force is inversely as 
“ the square of the distance, the curves to be squared are a cubic hyperbola, y n _L, 
“ and a cubic conchoid, y 1 — —— ; therefore the equation to the trajectory is 
“ ( a—xjly? — x x*, which belongs to a cycloid, the radius of whose generating circle is 
“ a. In general, if the force be inversely as the with power of the distance, the equation 
“ of the trajectory will be ( a m “ 1 — x m “ 1 ) y* — x m ” 1 x 1 , which agrees also with the 
“ first case, where ‘m being = 1, a m - », may be esteemed the hyperbolic logarithm 
“of u.” 
Edinburgh, 
July 2, 1796. 
H. BROUGHAM. 
