By The English Correspondent Op The Scientific American. The recent achievements of the steamship "Lusi-tania" have stimulated increased interest concerning her sister vessel "Mauretania," which will, it is antici pated, accomplish even better performances. Although almost identical in design, the results that were ob tained by her designers and builders, Swan, Hunter Wigham Richardson, of Wallsend-on-Tyne, in the builders' trials gave every indication of the "Lusi-tania's" high speed being exceeded. The later Cu-narder is, however, larger than her sister ship, the difference in tonnage being about 300 tons, due to an increase of 5 feet in her length and some 5 inches in her molded depth. The leading dimensions are as follows: Length over all, 790 feet; length between perpendiculars, 760 feet; breadth, sxtreme, 88 feet; depth, molded, 60 feet 6 inches; gruss tonnage, 33,000 tons; draft, maximum, 37 feet 6 inches; registered displacement, 46,640 tons. An important feature of her construction is the large proportion of high tensile steel that has been worked into her hull and upper works, a distinct advantage of this development being an appreciable reduction of her weight combined with an increase in her capacity. The cellular double-bottom principle of construction has been adopted with floors on every frame, and this double bottom is continued well up the vessel's sides. A powerful commission of engineers was appointed to determine the dimensions and propelling machinery necessary to fulfill the Admiralty's requisitions for a "speed of 24%' knots in moderate weather," together with the large passenger-carrying capacity that was aimed at, and numerous experiments were carried out at the government testing tank at Haslar by Mr. R. E. Froude. In addition other models were prepared and tested under the direction of Sir Philip Watts, the present Director of Naval Construction to the British Admiralty. At the conclusion of these investigations the builders, upon their own initiative, constructed a model 47% feet in length. This was propelled by electrically-driven mechanism, and a series of experi ments were carried out to arrive at the most suitable torm for the after lines of the ship, the number of the propellers, and their relative positions so as to achieve the most satisfactory results. These experi ments, which were Of the most elaborate description that have ever been carried out, were continued in cessantly over a period of nine months, and the data thus gained haveproved of supreme value to the build ers. These investigations were carried out by Mr. G. B. Hunter, D.Sc, who was ably assisted by Sir William White, the late Director of Naval Construc tion, in his capacity of consulting naval architect to the Tyneside builders, throughout the whole time occu pied in ner construction. The sum of these joint efforts has been the production of a graceful vessel having very fine lines, and one which at full speed throws a very small bow and stern wave. The machinery is similar to that installed in the "Lusitania," of which we recently gave particulars, and therefore omit them here. In regard to the appointment of the passenger ac commodation, the "Mauretania" excels her sister ship in luxury. The first-class accommodation for 560 pas sengers extends over the five uppermost decks, access between which is gained by means of the electric lifts, the incorporation of which was first suggested by the SCIENTIFIC AMERICAN, operating in the well of the grand staircase. This staircase is carried out in th* 381 style of (he sixteenth century Italian, the whole of the woodwork being in French walnut, with the panels veneered with the finest figured wood. The paneling is relieved by carved capitals and pilasters, in which repetition of design has been avoided, and the pre vailing impression is one of soft and heavy richness, relieved by the pleasing silvery tone of the aluminium "grille" or railing around the elevators. The dining saloons, of which there are two, are decorated in oak in the style known as Francois Premier, the type most closely followed being that prevailing between the years 1540 and 1550. The woodwork is richly carved, the panels being disposed so that no piece of carving resembles its neighbor. By this means a pleasing variety has been produced, some of the carving being of an exquisite nature, especially the arched bulkheads running at right angles to the sides of the ship. The upper saloon terminates with a lofty groined dome, and the crown of the dome terminates in a gilded convex disk, round which runs a balustrade sheltering hidden electric lights, whose illumination striking the disk is pro- jected in a soft bright radiance into the saloons below. The lounge is carried out in the late eighteenth cen tury French style. The room is attractively broken up by symmetrical semicircular bays flanked by fluted columns, which with the panelings are of mahog any, cross veneered to give the best effect to the figur ing. A dull polish of golden brown is imparted to the wood surface, blending harmoniously with the rich gilt of the carvings and moldings. The furniture is executed in beech and upholstered with various colored brocades, which are all reproductions of the Louis Si -i ' ? [ ] ? 1. : ? il 1 I :i It i . :? ]1?-:? -iii. :iml -.11 ik ing conlia ? In Hi.....H.....G l:ii-h m t? :? ? : ? -il I 11 - numerous ? ? 1 - - : 11 - inaili- ? " [ ? - plain llmiuli ?] i -?? ?-it and of ? :?? " in-; 1?:? -- :iml ? ilm - The li 1 ? : ? r wall pam-li'i.; in :??:??- ni" c-viii--ite grain -:?????-1 MIU-.1 -;?:G ? In - : 11 ? 1 ?:?11??? - being gill : ml l lu- i-s. ' ??? -i 1.....1,???,? ln-iiu ? : : ? 1 - lu constitua- mu- wall ni lin- :?:?? ??:?-?? "G?? 11 ? i covered b- a 11-?-] ?......mlnn-il : ? ]n-i willi :? 1 m :nli border, which J ? :?? :il-n ilni:iin:iii- ill.....Tin- frames ?? ihu chair and thu labium aiu caiiicd out in mahogany, and are copied exactly from the antique furniture of eighteenth century France. An excellent relief to the softness is afforded by the massive fire place, the chimney piece of which is of white statuary marble surmounted by a mirror, while the small-paned clear beveled glass doors afford an excellent view of the corridors in either direction for 350 feet. In the first-class smoking saloon the most interesting feature is the lounge extending the full length of the apartment, divided into recesses with divans and card tables. On all sides the room is broken up into entic- in mini. - :iml ? /' iniiii-i- while- ? In- window-. which : 11 - m' lai;i- -i/t- an- 11 ?? ] 111 - in -.hip i.....lalinn ln-ing [ ? -: 111- I Willi -?-?? ? ii c ular : 111 h - - im : lin I In- ap- J n t ? G ? 11.....I' il II 11 - 1 ii - : ? ] ????????' hull-?- l'util']' linw- i-M-r. ? In- ?? ? -I ??-:????? Un- In ?-]?]:?? ?- which i, m' 111 c ii]i f:i -liiiiin-il ?] ??-il I' ?.....I' !i ] ? ] ] - [inn, : ? t ? 1 -ni ?:???????-1 Willi a ninlu-i :? ? w.....I ??.....I 1 Imlli— aiii-r i I In- mu i- in I In - d.....lalinn m' lln- _~' 11' ( -t ] : ? ~ -.1:11 -] ?? ?? : ? :?? ? :ini-il [ : ? ? : 11 : ? n 1:111 -1'niiii inn- m lliU'i- ] : ? -.i-ngi-i , ae c m din.; m ] u ? -i ? imi ??G the cabin. Foi the inot pan the wall paneling is 382 carried out; in white, relieved with variously colored woods for the furniture, such as satinwood, oak, ma hogany, and walnut. The same scheme of comfort is continued in the second-class quarters, where there is accommodation for 375 passengers. In the fore part of the vessel, distributed over four decks, is the third-class accommodation. The dining saloon, which is the principal apartment, is 84 feet in length, extend ing the full width of the ship by 10 feet in height. It marks a decided advance in the provision of com fort and elegance for this class of passengers, 1,300 of whom can be carried, for the walls are paneled out in polished ash with teak moldings. Three hundred and thirty persons can be accommodated at one sit ting. Careful attention has been devoted to the problem of thoroughly ventilating the whole of the vessel, it being so designed as to enable a change of air through out the whole ship at intervals of ten minutes. The flow of air into each cabin may be controlled accord ing to the desire of the passenger; and while in sum mer the inflow may be cooled, in win ter it is warmed before admission. After the adjust ment of compasses in the North Sea and a few nrelimi-nary builders' speed trials over a meas-ired mile, the "Mauretania" trav eled 1,000 miles round the north of Scotland to Liver pool for dry-dock ing prior to her official speed trials. In the 1,200-mile test run her aver age speed was 26.3 knots; over a 300-mile course she averaged 27.36 knots, or about 31% land miles an hour —nearly a knot faster than the time made by the "Lusitania." Special attention has been devoted to the adequate ven tilation of the en gine room and stokeholds. It is stated in some quarters that with turbine machinery the engine room becomes insuffer ably hot; but ac cording to the ex perience of the en gineers upon the builders' speed trials, while the temperature is at times inconvenient, it is not intolera ble. In the case of the quadruple-ex pansion reciprocat ing engine,the high-pressure cylin ders, where the greatest heat pre vails, are elevated to a point well up in the engine-room space, and the hot air around the former in ascending induces a correspondingly stronger inflow of cool fresh air below. In the case of the turbine, owing to the high-pressure steam pipes being practically upon the floor of the ship, no such advantage as the above can be gained; but the temperature conditions can be ap preciably ameliorated by an elaborate ventilating system, such as has been installed. In the stoke holds, on the other hand, according to the evidence of the stokers, the heat is considerably below that gen erally prevailing upon an ordinary liner with cylin drical engines, and even when the steam is at the maximum supply and the highest pressure, the varia tion in temperature is never more than one or two degrees. For the construction of the "Mauretania" some 6,000 working drawings were made, of which more than half concerned the ship and the rest the engine equip ment. During the building of the ship, 5,000 employees were pressed into service, which number at times was augmented to 8,000 persons. For the electric lighting of the ship there are over 200 miles of cable, and the electric generating station is larger than that laid down for a good-sized town. In regard to her coal consumption, it is computed that for a round trip between Liverpool and New York some twenty trains each hauling over 500 tons of coal would be required; while to deal with this coal on board, 350 trimmers and firemen are required out of a total crew of 800 men. Considering the enormous cost of a ship of these dimensions and speed, the doubt has been expressed as to whether its operation will ever become a finan cial success. Upon this point the owners have not the slightest apprehensions. The value of the passage money that has represented the trips of the "Lusi tania" up to the present time has fluctuated between $175,000 and $200,000 per passage; and in view of the fact that the winter season is the slackest in the steamship traffic between America and Europe, the outlook for the busy summer season is decidedly auspicious, and the ships have the promise of a very considerable government subsidy. Alloys* of Aluminium and Magnesium. As magnesium is very much lighter than aluminium, and can be had at a reasonable price, there has been considerable employment of alloys of these two metals. It is well known that pure aluminium is too soft for sand castings. To harden it, it must be alloyed with another metal. For this purpose, zinc has been preferred; but in order to get the desired strength and hardness, an undesirably large proportion of the alloying metal is necessary. Copper also is employed for this purpose, less of this being needed than of zinc. As, however, both these metals are much heavier than aluminium, the alloys which they form therewith are also heavier. There are many cases, says a writer in the Deutsche Metall-Industrie Zeitung, where there is desired a, light aluminium alloy which shall also be tough and hard, and can be used where otherwise brass would be employed. As an addition to aluminium, magnesium has prop erties possessed by no other metal. Its specific grav ity is only 1.75, against, 2.58 for aluminium. It, hardens aluminium almost as well, although not quite so well as copper, possessing the additional advantage that only a small quantity of it is necessary in order to get the wished-for strength and hardness, these being very desirable qualities. The amount of magnesium which is usually em ployed for making an aluminium and magnesium alloy is about 10 per cent. More magnesium gives a greater degree of hardness. To make such an alloy, the follow ing mixture is made: 90 parts by weight of aluminium and 2 to 5 parts of magnesium. If the alloy is to be rolled into sheets or drawn into wire, less magnesium must be added; as a rule, 2 to 5 per cent. The addition of 2 per cent gives a soft alloy; 5 per cent a hard one. The aluminium is to be melted in the ordinary graphite crucible. When it is melted there should be added a trifle of cryolite, a min eral containing aluminium, fluorine, and sodium. This covers the surface of the aluminium, and protects the magnesium from oxides when it is melted. The latter is thrust down through the alumi nium by tongs, so that it melts and al loys itself with the latter, without com ing in contact with the air. All being next well stirred, it is then ready to be poured. The usual precautions as regards over heating and pour ing are to be ob served, as in the case of aluminium and zinc alloys. The temperature for the pouring is about the same as that for the other alu minium alloys. The tensile strength of the aluminium-mag nesium alloys is not so great as that of aluminium and zinc, but is about the same as those of aluminium and copper. The great advan tage in the employ ment of magne sium as hardening material for alumi nium is in the very slight weight of the alloy, which unites the hardness of brass with the ten-s i I e strength of cast iron. Such al loys are especially useful in the manu facture of scientific apparatus and other instruments of precision. A Hint for Inventors. During the in spection trip of Colonial Secretary Dernburg in Africa, while the committee was at dinner at Bukoba, Herr Schubert, a manufacturer from Zittau, Saxony, an nounced that he intended to give a prize of 3,000 marks ($714) to the inventor of a method of utilizing the juice of the Candelabra euphorbia. The discovery of such a method affords many difficulties, but upon the proof of the ability to utilize this product, as well as other up to the present time unnoticed treasures of the colony, the 3,000 marks will be given. The city of Paris owns 87,000 trees, or one to every thirty-two inhabitants, without counting the trees in some 300 acres of parks. The horse chestnut is the commonest tree planted by the municipality; after it comes the plane tree. In some of the more distant and secluded avenues limes and acacias are found, but variety must not, be sought outside the gardens and parks which belong to the State. There one may find almost every tree that may be grown in the Paris climate.