The Adjective-Formation Of Comparative And Superlative

Most Adjectives of one syllable, and some of more than one, form the Comparative by adding er and the Superlative by adding est to the Positive; as,
                                      Positive                 Comparative           Superlative
                                      sweet                       sweeter                  sweetest
                                      small                        smaller                   smallest
                                      tall                            taller                      tallest
                                      bold                         bolder                    boldest, etc. 

• When the Positive ends in e, only r and st are added; as,

                                     brave                       braver                      bravest
                                     fine                          finer                          finest
                                     large                        larger                        largest, etc.

• When the Positive ends in y, preceded by a consonant, the y is changed into i before adding er and est; as,

                                    happy                       happier                      happiest
                                   easy                          easier                         easiest
                                   heavy                        heavier                       heaviest, etc.

• When the Positive is a word of one syllable and ends in a single consonant, preceded by a short vowel, this consonant is doubled before adding er and est; as,

                                 red                            redder                          reddest
                                 big                            bigger                           biggest
                                 hot                            hotter                           hottest, etc.

• Adjectives of more than two syllables form the Comparative and Superlative by putting more and most before the Positive; as,

                                beautiful                    more beautiful               most beautiful
                               difficult                       more difficult                most difficult
                               industrious                 more industrious           most industrious, etc.

• The Comparative in er is not used when we compare two qualities in the same person or thing. If we wish to say that the courage of John is greater than the courage of Peter, we say,

                                           John is braver than Peter.
      But if we wish to say that the courage of John is greater than his prudence, we must say,
                                          John is more brave than prudent.

• When two objects are compared with each other, the latter term of comparison must exclude the former; as,     Iron is more useful than any other metal.