The Ericsson is getting new cast-iron crown plates, in place of wrought iron ones in her furnaces. The “New York Daily Times,” of Saturday the 26th, had a long article on the subject, and made one statement which contradicts a another made by Capt. Ericsson, in our presence. It says, " the bottoms of the cylinders are of wrought iron and convex in form, because n no foundry would cast them. During the first trial trip down the bay, under anything like a full pressure, the wrought iron bottoms e (it should have said crown plates) proved too c elastic. When the pressure reached nine " pounds, one or two ot the bottoms yielded from half to three quarters of an inch. Upon ,c the next trip, the pressure was less, and du- 1 ring the voyage south, it never exceeded e eight pounds. The remedy for this is simply to substitute cast-iron for the wrought-iron ' bottoms used hitherto ; Messrs. Hogg Del - 1 meter are now casting them." ' In answer to the foregoing we say, it will ' be remembered by those who were on board ' the Ericsson on her second trial trip, that 1 Alex. Jones, Esq., of this city, asked Capt. Ericsson it the crown plates of his furnaces were not liable to give way, and the answer he received was " NO." " Their form," (con-vex) said Capt. Ericsson, " allows them to expand and contract without danger." Said Mr. Jones, " the talk on 'Change among those who have a knowledge of such things is, they cannot stand." The "Times" says, in the, article referred to. " Practical engineers who make any pretensions to a mastery ot their profession are very careful even while dealing largely in annonymous and injurious insinuations not to put themselves on record against the speedy and complete success ot the caloric engine."- Thitis untrue ; we can get the opinions of fifty engineers, if we choose, to put on record against its success, while the world lasts. How does this accord also with the statement and question of Mr. Jones ? it has already come to pass what engineers talked of on'Change, and which Capt. Ericsson denied, and which we heard with our own ears. The " Times " also says, " The theoretical demonstrations with which many of our so-called scientific journals lately abounded that the use of heat over and over again for the purposes of motive power was absolutely and simply impossible, have already vanished altogether." No paper professedly devoted to science but the Scientific American has put forth theoretical demonstrations, to prove the principle ot using heat claimed for the Ericsson, erroneous. The advocates of the Ericsson claim that a certain amount of heat by the use ot packages of wire gauze can be made to produce an infinite amount of motion—strokes in an engine. We deny this, it is against all the established laws of mechanical philosophy, and there is not a single scientific engineer or professor of mathematics and engineering in our country but will, if called upon, corroborate our views ; if we are not correct the Principia of Newton is trash, and the philosophy of mechanics as taught in our colleges for two centuries (but which the editor of the " Times " has never learned) and is now taught there, is false. If a definite quantity of heat can produce an infinite amount of motion, there is hope for the static pressure engine yet, although we exploded that humbug more than a year ago, the principle claimed is the same in both cases. In conclusion let us say that cast-iron crown plates for wrought-iron ones is a new idea in engineering, but as poor as the use of hot air. What engineer of common sense would use cast for wrought-iron in a high pressure boiler. We now say and call upon all to mark our words, that the cast-iron crown plates will soon be found as useless as the wrought-iron ones. So far as it regards anything the " Ericsson " has yet done, our readers will see that their confi-ll\ dcnce in our opinions has not been misplaced.