Returning home, he became an apprentice in his father’s factory at Ware, Massachusetts.  He was put into the dyeing and bleaching department, and was thoroughly trained in it by Mr. William T. Smith, a scientific man, and one of the best practical chemists in New England.  Young Holt manifested a remarkable aptitude for chemistry, and when but a mere boy was known as one of the most successful and dexterous manipulators in New England.

When he had reached his eighteenth year, the old spirit of restlessness came over him again, and he embarked in an unusually bold undertaking for one so young, in which, however, he was much favored by the circumstance that he was very much older in appearance than in reality, commonly passing for a full-grown man.  Assuming the name of Dr. Coult, he traveled throughout the Union and British America, visiting nearly every town of two thousand inhabitants and over, lecturing upon chemistry, and illustrating his lectures with a series of skillful and highly popular experiments.  His tour was entirely successful, and he realized in the two years over which it extended quite a handsome sum.  The use which he made of the money thus acquired was characteristic of the man.

He had never abandoned the design of a revolving pistol which he had conceived on board the Coroo, and he now set to work to perfect it, using the proceeds of his lectures to enable him to take out patents in this country and in Europe.  He spent two years in working on his model, making improvements in it at every step, and by 1835 had brought it to such a state of excellence that he was enabled to apply for a patent in the United States.  His application was successful.  Before it was decided, however, he visited England and France, and patented his invention in those countries.  Though now only twenty-one years old, he had given seven years of study and labor to his “revolver,” and had brought it to a state of perfection which was far in advance of his early hopes.

“At this time, and, indeed, for several years after, he was not aware that any person before himself had ever conceived the idea of a fire-arm with a rotating chambered breech.  On a subsequent visit to Europe, while exploring the collection of fire-arms in the Tower of London and other repositories of weapons of war in England and on the continent, he found several guns having the chambered breech, but all were so constructed as to be of little practical value, being far more liable to explode prematurely and destroy the man who should use them than the objects at which they might be aimed.  Unwilling, however, to seem to claim that which had been previously invented, he read before the Institution of Civil Engineers in England (of which he was the only American associate), in 1851, an elaborate paper on the subject, in which he described and illustrated, with appropriate drawings, the various early inventions of revolving fire-arms, and demonstrated the principles on which his were constructed.”