However, many learned gentlemen were influenced by Mesmer, such as John Elliotson, James Esdaile and James Braid. Braid moved forward from the techniques of Mesmerism to discovering that using just words could evoke trance which marked the end of Mesmerism. James Braid also pioneered the term Hypnosis.
Hypnosis took a dip in popularity in the mid 1800's due to the arrival of chloroform and ether, with many famous figures such as Queen Victoria steering towards the route of drugs.
Sigmund Freud was known to use hypnotic techniques alongside his own methods of treatment, it is well documented that he wasn't very accomplished in hypnosis.
From the mid 1800's many different techniques have been developed such as Ivan Pavlovs - conditioned response, Emile Coues - auto suggestion and Milton Ericksons - indirect suggestion.
From the 1970's NLP (neuro-linguistic programming) was created by Richard Bandler and John Grindler and has become a popular addition to techniques used in hypnotherapy. Technically not hypnotherapy, it uses the use of language to effect changes in behaviours and thoughts.
So to date hypnotherapists have a large pool of resources to achieve the best results, excluding of course, the iron fillings!