210 Class 5.— MACHINES FOE DIRECT USE, INCLUDING! CARRIAGES, [United

North Areas A. B. 10 to 34 ; 0. D. E. 1 to 10, & 19 to 33 ; F. 1 to 32 ; G H. 1 to 13, & 19 to 26.

The Marine Engines, which are not in motion, form an extremely interesting study. The ponderous enginesfrom the Soho Works, of the collective power of 700 horses, for driving the screw propeller by direct action,form a remarkable illustration of the revolution effected by progressive science, not only in the form, but alsoin the application, of the steam-engine. The time existed when the great improver of the steam-engine ques-tioned the probable application of steam to ocean navigation ; and it is remarkable to find these immenseengines, exclusively adapted to steam navigation, proceeding from the works founded by James Watt himself.Upon these engines are wooden models of an attempt at steam locomotion made as early as 1785.

Separate parts of machines and specimens of workmanship are also exhibited. Among the former will berecognised the enormous connecting rod, adapted to marine steam-engines, of the collective power of 800 horses.Some beautiful specimens of straight edges and flat surfaces are also shown. Hydraulic presses of variouskinds are exhibited, and among them the vast machine which was employed to lift the Britannia tube into itsplace. The application of the same powers is also shown in other directions. Cranes of various kinds are foundin this Class—the peculiar form of the tubular iron crane, of the Derrick, and other cranes, will attract atten-tion. The Derrick crane was employed in the construction of the building, and in placing the heavy machineryin situ.

The high reputation enjoyed by the locomotive engine-makers of England is adequately sustained by themagnificent and costly engines found in this department. The. stupendous wide-gauge engine—the “Lord ofthe Isles”—illustrates the peculiar features of construction introduced on that system, and conveys an over-whelming impression of speed and power. In contrast are the beautiful engines for express travelling—theCornwall , and another, built on Crampton’s patent: the driving wheels of the latter are eight feet in diameter.These engines are calculated for a high degree of speed, with great power. Corrugated iron carriages, carriagesbuilt of Moulmein teak, breaks, trucks, turn-tables, signals, specimens of permanent way, and all that relatesto the railroad system, are therein abundantly represented.

Carriages of every description are found in their proper place. Some of these are of new form and design,others combine new mechanical adjustments or adaptations, and others exhibit improvements instituted forparticular purposes, as for convenience in travelling or for the removal of invalids. Public carriages, of newforms, are also found among others.

This Class, viewed as a whole, indicates in what direction the current of industrial activity has been mostsuccessfully conducted in Great Britain. The workmanship employed in the reduction of ponderous masses ofmaterial into forms capable of exercising movement and developing force, is of necessity of the highest order ;for an error of adjustment were fatal to the operation of these mighty engines, and the difficulty of accurateadjustment presents itself, at a rough estimate, proportionately to the size of the object concerned. But spe-cimens of the successful application of mechanical skill in every direction, and to objects great and small, arefound, and appear in forms which indicate that compactness and completeness of execution are not lessregarded than perfection of adaptation. As the practical display of the sources of power at the command ofthis country, whether in their application to production or to locomotion, Class 5 is complete, and offers a widefield of fruitful investigation to the inquirer.—R. E.

1 Atherton, Charles, Dockyard, Deconport —

Inventor.

Pair of marine steam-engines of 25-horse power, con-structed with a view to apply the sway-beam principle indriving the submerged screw propeller.

Drawing, to show the mode of applying the same prin-ciple to large engines for ships of war, which requirethe engines to be below the water-line of the ship. Theair-pump valves are adapted for being worked with greatspeed, and the eccentrics and slides are arranged for beingeasily managed, so that the engines may be quickly re-versed. The patent expansion gear is intended to bemade one of the principal means of registering the varia-tions of expansion during the working of the engine, inorder that the indicated working power and the corre-sponding consumption of fuel may be duly recorded; thusapplying to marine engines a system of inquiry whichhas been attended with great advantage in the case ofmining engines.

Model of the expansion slide.

2 Powell, Edward James, 11 Hartland Terrace,

Camden Town —Designer.

Drawing illustrative of the various forms of patentscrew propellers. __

3 Smith, Captain F. P., Greenwich.

Various screw propellers.

4 Stothert, Slaughter, & Co., Avonside Iron Works,

Bristol —Inventors and Manufacturers.

Patent combined propeller engine, patented by Ed-ward Slaughter. This system, which has reference onlyto condensing propeller engines, purports to combine theadvantages of a direct-action, quick-working engine, withthose of the indirect slow-working engine. In the latter,

the speed requisite for the propeller is obtained by meansof accelerating gearing driving on to a second-motionshaft. The new engine claims to avoid the disadvantagesof both. It is assumed that, to attain the best possibleform and angle of screw, it is in all cases desirable to givea speed to the propeller shaft unsuited to the vacuum,supply, and bilge pumps, but especially to the former;and that whereas the required number of revolutionspresents no practical difficulty in those portions of theengine where the passage of steam only is in question,very great difficulty, and an undue amount of wear andtear, as well as loss of power, attach to the rapid opening,closing, and constantly repeated shocks of large and nu-merous valves, required for the passage of water throughthe vacuum pumps for the process of condensation. Sogreatly is this difficulty estimated by some of the firstnaval engineers of the day, that the direct engine, withits cumbersome and costly gearing, is preferred to thelight, simple, and inexpensive direct-action engine ; andthis preference obtains in spite of the very strong preju-dice entertained against the employment of gearing in anyform on shipboard. Under the present system, direct-action to the screw shaft from the steam pistons is ob-tained, in connection with a reduced speed of the vacuumapparatus, by means of gearing of a lightness proportionedto the fraction of power required, say part of the en-tire power of the engine. It may be said that direct-action engines are in successful operation, in which thevacuum apparatus is made to work, without difficulty, atthe same speed as the steam pistons. Now, if this cannotbe denied, it is submitted that the speed, and thereforethe angle of the propeller, must be lowered to the speedsuitable for the vacuum apparatus; that they do so workat a considerable loss of power, by reason of the undulylarge relative capacity of the air pumps, at a much increasedratio of wear and tear of machinery, and, as it can scarcely