We have already noticed that a commission has been appointed by the Secretary of the Navy to test, upon a large scale, the advantage or disadvantage of using steam expansively. The m embers composing that commission are Messrs. B. F. Isherwood, Theo. Zeller. Kobt. H. Long, and Alban C. Stimers, all chief engineers in the naval corps, and Capt. Joseph Lanman, executive officer of the U. S. steamer Mchignn. Thit our readers may more cleaivly understand the reasons for such an extended series of experiments as are in c on tem plati on, it will be well to sttite briefly th a Mr. Isherwood, diuing the last Sprmg and summer made n umerous experiments at No. 239 Cherry street, this city, on a small condensing engine, constructec purely for experimental purposes. with a view tc ascertain the comparative economy of using steam with a peculiar method of superheating. In th course of these experiments it became necessary t( greatly vary the conditions under which the steam was used, in order to determine whether the same result from the superheating followed with every variation ii the condition of the steam. Aceordingly, amongst others, an ex tensive set of com para tive expe^-iments were made with the s team used expansively, and wi th out expflsi on; when, to the surprise of th ose in charge, it was disco\'ered that no economy followed the use of expanded steam, even under the most favorable circumstances . These experiments being made upon a single hors power engine, it was thought by many' of our engineers and large manufacturers that the facts there attainet woul d not hold good wh en t^^ed u pon .a m ore exten sive scale; consequently a petition was sent to the Hon Isaac Toucey, Secretary of the Navy, requesting the government to try the experiments upon a large scale. With an alacrity highly commendable, and such as he has ever evinced in advancing the cause of engineering in this country, he appointed the present board. The U. S. steam er Michigan, now in wi n ter quarters at Erie, was placed at t heir disposal, and it was d eci ded that the experiments should be commenced forthwith. This steamer has very recently been supplied with two new boilers of the Martin vertical tubular description, and her machinery has been thoroughly repai rcd under tlie personal supervision of Chief Engineer Zeller. Her cn^nes are of the same plan, and vciy similtir to thlfse of the Harriet ia'ric ; the'' wore dE!li!gtfed by Mr. Charles Copeland, and constructed by Messrs. Stack-house & Tomlinson, of Pi11sburg. The cylindei-s are 36 inches in diameter ; length of stroke of pistOIl, 8 feet, and the wheels are 21 feet 6 inches in diameter. The floats are in two parts, 17 and 14 inches w ide by 8 eet in length ; dip of wheels, 27 inches, when the iteamer draws 7 feet of water, w.hich draft she is deigned to have during the ex pcri m en ts. The Michigan is const^-ucted of iron, but the framing )f her engines is wood. Her principal dimensions are is follows :Length, on deck, 163 feet 6 inches ; breadth of beam, 27 feet; depth of hold, 12 feet ; she is he only U. S. steamer on Lake Erie. The instructions of the board are that both engines be fitted with indicators, and a tank supplied for measuring the feed water, previous to its being pumped into the boilers from the hot well. The coal to be used is the bituminous, from the Ormsby mine ; this is to be carefu lly weighed, together with the clinkers and ashes. Observations are to be made every hour, and the number of revolutions, steam pressure, vacuum, barometer^ temperature f tank, injection water, engine and fire-room s, are to be cirefully noted. Indicator diagrams at each end of the cylinders, and the evaporating qualities of the boilers, with the amount ot steam gener.ated to each pound of coal, both by indicator and tank measurement, are also to be made. The pressure in the boiler is to be kept, as far as possible, at 20 pounds per square inch ; the dip of the wheels to remain the same duiing the whole course of the experiments. The throttles are to remain unaltered during each experiment, and the number of revolutions to continue, as far as practicable, the same. Each experiment is to occupy seventy-two consecutive hours, and they are to be made in the following order: 1st. Both engines cutting off at one-quarter stroke. 2d. Both engines cutting off at one-half stroke. 3d. One engine cutting off at one-half st^-oke. 4th. One engine cutting off at three-quarter stroke. 5th. One engi ne cultng off at lull stroke. Addi tion al clauses, i ncorporate d with in the general order, give the board pewer to experiment further upon such points as they may deem necessarv, and verbal instructions leave them no alternative but to use every possible exerti on, and e m pl oy all their time to .arrive at positive conclusions upon the subj ect. The board, amongst others, design to experiment upon the following points :The friction of the engines by removing the floats .and running without them ; the compara tive effect of working with low stcam, full stroke, by reducing the initial pressure, and by cutting off at two-third s the stroke. The high official character of the members composing this board is such that we can safely vouch that their numerous experiments will be conducted with the greatest care, and that the various points upon 'which they must decide will be tretited in an able and i m partial manner. 'Ve have the assurance that they enter upon their duties designing to arrive at the truth, and it only. Many persons who deny that there is any econom y in working steam expttnsively, quote :ir. Isherwood as authority in support of their position ; this gentleman does not seem to be rightly understood upon this question. He does not deny that there is anv economy in thus working steam ; on the contrary, he reeognizes this economy fully, but he does con ten d, tliat from the various experiments he has alre.ady made, the advantages th us gained, are n eu tral ized by the greater friction of the enlarged cyl in der necessarily em ployed, the increased back pressure upon the larger piston, a.nd tbe condensation of the steam by expansion. These experiments will command universal attention, and we, among many o t.hers, wil l an xi ously await the development of the result to be attained. Further, we trust that all engi n eers, manufactu rers of m ach i nery, &c., &c., will aviil themselves, as far as practicable, of the kind i nvi tation of Mr. Toucey to be p re sent at som e if not all the experi m ents that are to ba made. We can a.sstle thcm they will be received with kindness by the gentle-m anly board now in session. THE copyright of Webster's Dictionary yields $30,000 a year; and of his "Elementary Spelling Book" 35,000,000 of copies have been sold, the annual issue now being upwards of 1,000,000.