On page 20, this Vol., Scientific American, we gave a brief notice of a machine for turning irregular forms, stating that we would soon publish the engravings of it. We were induced to present that notice, as such machines have a very extended interest, and because the word of the owner was promised for the engravings. His promise has not been kept ; we regret this for his own sake, and for the future we will take care and promise no engravings of a machine until we are sure of being able to present them. We make these statements because we have received letters asking why the said engravings did not appear according to the announcement made. The Hot Air Ship made a trial trip on Wednesday, the 5th inst., and with a strong wind and tide in her favor, made about 11 miles per hour.