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the Hasla station by two years which gives it a peculiar interest in that it followed closely the arrangement of the first admiralty tank at Torquay. In particular, the rails for the car- riage were suspended from the roof over the tank with only sufficient space between the rails for the con- venient handling of the model and the recording apparatus. The carriage is very light so that the longitudinal os- cillations of the wire towing rope does not give any trouble with the rope directly connected to the carriage. There appears to be no' thought of substituting electric traction, nor does that appear to be convenient. The possession of this station has enabled the firm to take a leading position in the solution of certain problems in naval architecture such as very high speeds for paddleboats and the installation of steam turbines. It may be interesting to rehearse the first notable means that they owed to towing experiments. In 1888 -the firm desired to bid for the construc- tion of a fast paddleboat which was required to have at least 19% knots speed on a length of 300 ft. and a beam of 35 ft. At first the scientific staff hesitated when the firm expressed a desire to guarantee at least a knot more than the required speed; but after tests on several models it was decided that a speed of 20% knots could readily. be promised, and on trial the ship showed a speed of 21.6 knots. The model selected had a beam of 38 ft., or three more than that specified, which were in direct opposition to the common opinion at the time. In passing, it may be re- called that for paddleboats the loca- tion and form of the waves which ac- company the boat and come in con- tact with the hull, together with the location of the wheels with. reference to such waves, is of prime impo t- ance, and such question can be intel- ligently investigated by aid Of the -ex- periments on models with compara- tively little trouble and expense. It is most remarkable that while most explicit information based on exper- iments and experience now exists for screw-propeller propulsion of ships, the printed information with regard to paddle wheels is very scanty and unsatisfactory, and requests for in- formation, such as dimensions, revo- lutions and speeds, are not welcomed by those who have information. A member -of this firm expressed the opinion to the writer that every important yard would do well to have its own tank, and said that even with their large amount of accumulated in- TAE Marine. REVIEW formation they kept the tank busy and would give work to another tank if they had it. How different this is from the common opinion that, if only such a tank could be _ installed, - it might take in work for all the ship builders in the country. At the same time an opinion was expressed favor- able to the establishment of an "open" tank not hampered by governmental. secrecy or trade jealousy, at which scientific problems could be investi- gated, such as the best forms and pro- poztions for various speeds and con- ditions. The need for such work was emphasized to the writer by the fact that he found those in charge of a recently established private station engaged in just such an investigation while it may be fairly assumed that every well-established station has that information filed away for ready ref- erence. | The next station in point of time is that at Spezia, belonging to the Italian government, which has always shown boldness and originality in the development of its navy. As might be expected, it resembles very closely the Hasla station, and still has 'the car.drawn by a cable, though the sub- stitution of electricity is under con- sideration. An obvious feature was the substitution of brass and steel in place of mahogany, by the instrument maker intrusted with the construct:on of the apparatus, but good discret on was shown and the changes need not necessarily be open to criticism. This station had the greatest interest to the writer because it, like our Washing- ton station, is liable to have a temper- ature of 95 degrees Fahr., and yet the models were made of paraffine; they, of course, are immersed when not in use, and tests may not be made dur- ing exclusively hot weather. The opinion was expressed by Capt. Bon- figlietti that the main difficulty in the use of paraffine came from the dis- tortion due to unequal expansion of the parts of a model exposed to the air or to water when in use, and that for this reason the models should not be more than 13 ft. long. On >the other: hand, models as long as 20 ft. are made of paraffine at Berlin, where occasional high temperature is to be expected. The details of the instal- lation of this station, and reports of important investigations, such as the influence of depth of water on speed, are given at length in a large volume published by Col. Rota, of the corps of naval constructors. They have at this station a car- riage for testing two or th- ee propel- lers at a time in place behind a model, 17 and an arrangement for four propel lers is under construction. In _ the preparation of model propellers, draw- ings are made at a convenient en- langed scale which are reduced photo- graphically to the required size. A wooden model is then made to these drawings which is used as a mold for casting the composition blades. This method may be contrasted with the method devised by Froude and com- monly followed, in which the face of the blade is cut in plaster of paris to a true helical form; the blade is then molded in wax on this surface; then a back is made in plaster, which with the face (after the wax is removed) form the mold for the composition blade. The composition is a readily fusible alloy of tin, lead and bismuth. Much trouble was experienced from vegetable growth in summer, but that has been obviated by using copper sulphate in the proportion of one to three hundred thousand. Incidentally, this copper salt stained the oo an > agreeable green tint. The fourth station to be sctabliehed, and the second for a private company, was that at Bremerhaven, belonging to the North German Lloyd Steam- ship Co. This has been used in deter- mining the forms and dimensions of new ships for their fleet. Work has also been done for foreign govern- ments and private firms, both German and foreign. The carriage has a steel frame made of vertical tubes and diag- onal ties and appears to be light and rigid. It is driven by two six-H. P. electric motors and was the first so ets "At Chasisahuie. near the Tech- nishe Hochschule, is a'station that is owned in common by that institution and by the German admiralty, the lat- ter having exclusive control for cer- tain months each year. When seen by the writer the station was under ad- miralty control and was used for the investigation of the action 'of a ship in a narrow channel: with sloping sides like a ship canal. ie. carriage is constructed of 'steel angle bars. of small section, and appeared to be fairly light and stiff. It is drawn by a separate driving or 'locomotive car which had two electric motors. A new device was seen for testing four propellers behind a model, which was said to give satisfaction; it was cov- . ered with canvass and was not ex- hibited. Models. are sae up: to 41 ft. in length of paraffine, and while pro- longed hot weather may not be ex- pected, occasional :high temperatures are experienced. This is 5 ditteresting)