About a year ago some of the London journals, devoted to engineering, published a number of articles on the folly of employing side-lever engines in steamships, and advocated the superiority, in every respect, of the oscillating engine for the same purpose. These articles have found a second-hand advocate on this side of the Atlantic. It is said, now, that the side-lever engines of the Collins' steamers are mere copies of the English Marine Engine, and that these engines were put in to give confidence to the American public, or they would not have found any patronage; that is, passengers would not sail in them. It is also said that if these ships were to be built over again, the oscillating and not the side-lever engines would be employed in them. The objections urged against the side-levers are, " they occupy so much room, being more bulky, and consequently more expensive." The oscillating engines, on the other hand, are more compact, consequently they are not so expensive. Well, supposing our steamship companies adopted the oscillating engine in preference to the side-lever, would this not also be merely copying after the English engine ? Assuredly it would; what is the difference, then, in this respect? Nothing. But would the Collins Company, if they had their engines to put in again, adopt the oscillating kind ; and would the able engineers of the Noveltyand. "Ill'lllii Ulinlin1 IIin jnTTrrrnrr to the side-levers ? We believe they would rot. It is evidence of narrow-mindedness to refuse to adopt a good thing because it is foreign, and it is a sign ot good sense to adopt an excellent thing whatever paternity it may Mlve—Indian, Chinese, or English. Those engineers who prefer, at least in heavy and expensive engines, to adopt those of tried and proven qualities, exhibit more wisdom than those who adopt, recklessly, less expensive but untried and unproven engines. It is all very well to write long vaunting articles about this and that evil in present modes of engineering, but when this is done without facts to back up assertions, we may set down the writer as ? better paragraphist than practitioner. In 1848 a Commissioner was appointed by the British Government to examine into and report upon the state of the mercantile marine steamships. The President of the West India Mail Company gave in his evidence in ta-VOT of the side-lever engines for steamers; and, until we have further practical data to guide us, we must say that those engineers who counselled the side-levers for the Collins' steamships, exhibited sound judgment and good sense. It is not the mere economy of space and price of an engine at first, which, in the long run, provesmost economical. The economy ic repairs and general expenses must be looked into. An engine can be built of equal pows^vith another and not cost one-half as much to construct it. It may run well for a while, but, in the course of a year, it will cost perhaps five times more for repairs, and never at best give satisfaction. We must remember, that every week which a large steamship is unnecessarily laid up for repairs, involves a great loss in the mere interest ol money invested in its construction. How necessary, then, to count well the cost ol what kind of engine should be employed in a steam ship. In our opinion, the side-lever is the most economical, and therefore the best for steamships exposed to Atlantic storms. A] the parts are so well braced together, and so arranged for steadiness ot action, that, in our opinion, the oscillating is greatly inferior to it ? The beam engine has beautiful adaptations for working the pumps, and although it occupies more room than the direct acting engine, still, jt is no more an objection against its employment than it would be against the oscillating engine, for other purposes, because it is more bulky than the steam wheel. We have practical data for the side-lever engine, where is data for the superior economy of the oscillating marine engine? A new engine cannot be put into a large steamship every two or three years; neither will it do, to put out more for repairs, in the course-of a few years, than the whole original cost of the engine. We are the advocates of sensible improvements, but no friends to innovations for mere innovation sake.