Gentlemen,--I have received your polite invitation to the Printers' Festival in honor of Franklin, on his birthday the 17th of the present month, and regret that my engagements in the city put it out of my power to be present. I thank you kindly for the flattering notice you are pleased to take of me in connection with the telegraph, and made peculiarly grateful at the present time as coming from a class of society with whom are my earliest pleasurable associations. I may be allowed, perhaps, to say that in my boyhood it was my delight, during my vacations, to seek my pastime in the operations of the printing-office. I solicited of my father to take the corrected proofs of his Geography to the printing-office, and there, through the day for weeks, I made myself practically acquainted with all the operations of the printer. At 9 years of age I compiled a small volume of stories, called it the 'Youth's Friend,' and then set it up, locked the matter in its form, prepared the paper and worked it off; going through the entire process till it was ready for the binder. I think I have some claim, therefore, to belong to the fraternity. The other letter was in answer to one from a certain Solomon Andrews, President of the Inventors' Institute of Perth Amboy, who was making experiments in aviation, and I shall give but a few extracts:-- "I know by experience the language of the world in regard to an untried invention. He who will accomplish anything useful and new must steel himself against the sneers of the ignorant, and often against the unimaginative sophistries of the learned.... "In regard to the subject on which you desire an opinion, I will say that the idea of navigating the air has been a favorite one with the inventive in all ages; it is naturally suggested by the flight of a bird. I have watched for hours together in early life, in my walks across the bridge from Boston to Charlestown, the motions of the sea-gulls.... Often have I attempted to unravel the mystery of their motion so as to bring the principle of it to bear upon this very subject, but I never experimented upon it. Many ingenious men, however, have experimented on air navigation, and have so far succeeded as to travel in the air many miles, but always with the current of wind in their favor. By _navigating_ the atmosphere is meant something more than dropping down with the tide in a boat, without sails, or oars or other means of propulsion.... Birds not only rise in the air, but they can also propel themselves against the ordinary currents. A study, then, of the conditions that enable a bird thus to defy the ordinary currents of the atmosphere seems to furnish the most likely mode of solving the problem. Whilst a bird flies, whilst I see a mass of matter overcoming, by its structure and a power within it, the natural forces of gravitation and a current of air, I dare not say that air navigation is absurd or impossible.