It is well known to our readers that we have expressed our opinion that " hot air as a motive agent can never supersede steam." We have given some reasons for entertaining such an opinion, but not all that might be adduced in support of it. In opinion, we have stood nearly alone among the public press of our country; that is, no paper or magazine devoted to news, literature, science, and art, has expressed a decided opinion with arguments attached respecting the successor failure of the Ericsson. What we have said has been expressed calmly and in the most moderate language, but because we have so expressed opinions in opposition to those of some editors who have no scientific knowledge, and who are not capable of passing judgment on such a subject, they have not scrupled at hasty and untrue assertions in speaking of us, although we have given no occasion for personal remarks to any one. On the 11th of last month (Jan. 1853) the Ericsson made her second trial trip down the New York Bay, with the Corps Editorial of New York City, and on Friday last week the 11th Feb., she was opened for visitors, a month exactly from her trial trip, during which time she has been undergoing repairs at Williamsburgh, or rather getting her finishing touches, Captain Ericsson having stated on her trial trip that " she was not yet fit for going to sea, as her valves and pistons had not been rendered completely air tight." It will no doubt be very difficult to keep them tight, but if any man can do it Capt. Ericsson can. She is now said to be perfected in every part of her machinery, but we cannot forget that on the 12th of last month, the " New York Tribune," warmed with undue excitement, used these words:"The age of steam is closed, the age of caloric opens, Fulton and Watt belong to the past, Ericsson is the great mechanical genius of the present afid future." One month since then has passed away, the Ericsson was lying all that time getting repairs, and we have not heard of a single steamboat striking her colors to hot air. Every paper in our city used nearly as extra agant language as the "Tribune," especially be " Herald" and " New York Times. Per-aps a month has cooled their imagination nd led them to sound reason ; it at least has one so to the " Tribune." In that paper of be 1 lth inst., one month exactly from the ay of the Ericsson trial, and thirty days ex-ctly from the time it declared " the age of team closed," we find these words in a lead-Qg editorial :" Had Capt. Ericsson succeed-d in transmitting the moderate force excited nder his main pistons to the crank shaft, he days of steam as a marine motor might erhaps be about to be numbered." Here, with-ut any apology for its former wild assertion, the age of steam is closed," it now says, if 11 the direct power of the hot air was com-aunicated to the main shaft, (two-thirds aore than what it had before,) the age of team might be about numbered. This is cer-ainly coming down a peg or two, and not a very ingenious manner. We have not seen a solitary scientific argu-nent presented by the hot air advocates in fa-'or of it as a superior substitute for steam, ind we are thereby convinced that they are ill deficient in scientific knowledge. Now a ;ood argument might be presented in its fa-roi based upon its inferior capacity for ieat, which is as 3.72 to 1 against water. We confess that a good argument could be ad-luced in its favor based upon its atomical lumbers, and as Jonathan Edwards would say about a theological question, " it would .ook strong until it came to be handled, when 't would fall to pieces." We will endeavor to present some arguments for and against it next week, and in the meantime wish the Ericsson a safe and prosperous first voyage.