William Dana Orcutt records in Good Old Dorchester. Cambridge: John Wilson & Son, UP, 1893, pp. 382-383:

"In 1840 Mr. Hughes competed, with several others, for an equestrian statue of Washington, to be erected in Philadelphia. A Philadelphia paper, under date of November 24 of that year, thus refers to the model indicated: —

"Among all the models exhibited in Philadelphia for the decision of the committee on the Equestrian Statue of Washington, that of Ball Hughes, Esq., the distinguished sculptor, seems to be the favorite. The sculptor has chosen the time when the hero is in the act of reining up his horse, and bowing with his hat in his hand to his assembled countrymen. The design is a happy one. The attitude of both horse and rider is perfect. The horse, like another Bucephalus, carrying another, a greater than Alexander, seems proud of the precious burden which is entrusted to his charge. The likeness of Washington is the most perfect that we have ever beheld. All who have seen the statue agree that the mild and dignified countenance of him 'who was good without an effort, great without a foe,' is the most correct that any sculptor has yet chiselled [sic]. The graceful bend of the body is also in just keeping with the rest of the figure. In Mr. Hughes' design we see everything to admire, and nothing to condemn. It will at once be a proud and lasting memorial to the 'Father of his Country,' and a pride and ornament to our city. Although not so colossal as the equestrian statue of Peter the Great at St. Petersburg, yet there is a greater finish, a more perfect uniformity, and boldness of design in the statue in Independence Hall."

"Another paper says of the model: —"

 

"The model of an equestrian statue of Washington, which has just been prepared by Ball Hughes, Esq., is an exquisite specimen of the Fine Arts, and is creditable alike to the artist and the country. Grace, beauty, and dignity are combined, and the father of his country has an appearance at once benignant and patriotic. The horse, too, is also finely proportioned, and the effect of the entire model striking and imposing to an eminent degree."

 

"The opinion of the press was echoed by the public, and the committee did Mr. Hughes the honor of selecting his model from all those offered in competition. The financial crash which occurred in that year, however, destroyed all hope of getting up the statue at that time, and the project had to be given up, much to the sculptor's disappointment, and to the loss of the city. The model, as prepared for exhibition at Philadelphia, is now in the possession of Mr. B. F.
Brown, of Boston, Mr. Hughes' son-in-law."

"Success seemed destined to reward Mr. Hughes' exertions; but his aspirations were made futile by the failure of the committee on the Washington statue to carry out their contract.  The disappointment was bitter, and both the artist and his wife felt it keenly.  This ill-fortune in Philadelphia caused them to come to Boston."

"In 1841, the Library bought the plaster model for the equestrian statue of Washington with which Hughes had entered—and won—the Philadelphia competition mentioned above. Unfortunately, that commission was never fulfilled and Hughes evidently gave or sold the cast to Isaac P. Davis who then sold it to the Athenæum.[9]"...

"[9] Georgia S. Chamberlain, “Shorter Notes: The Portrait Busts of Robert Ball Hughes,” Art Quarterly 20 (winter 1957): 385. Hughes bought his model of Washington back from the Athenæum in 1858 for $100. In 1924, the sculptor’s descendants gave it to the Society for the Preservation of New England Antiquities (“Notes and Gleanings,” Old-Time New England 15 [July, 1924]: 47.)"