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1900.) MARINE REVIEW. | 17 cooking is required--only an hour or two; but in other cases it is con- tinued for six or eight and sometimes as much as fifteen or eighteen hours. In the best and most modern practice it is usual to conduct this treatment according to certain established temperature curves, which differ not only with different amounts and varieties of oil, but also fox different resins; the less scientific makers depend on the appearance of samples taken for inspection from time to time from the kettle. It is hardly ever possible to make a varnish in one operation which has the combination of qualities desired by the consumer; it is necessary to make a mixture of two or three of widely differing properties. The art of mix- ing varnishes is one of great complexity, and calls for complete knowl- edge not only of the component parts but also of their effect in combina~ tion. After the varnish is made and put in the tank it undergoes changes for some weeks or months before it arrives at a stable condition. VARNISHES MUST BE MADE FOR THE PURPOSES FOR WHICH THEY ARE INTENDED. Many people have the idea that varnishes are used for decorative purposes because of their beautiful surface, and that they are not suited to exterior use for protection against the weather. This belief is partly caused by the fact that paints for outside house painting, which have been mixed with enough varnish to make them glossy, have not proved very lasting; but this is because, not wishing to increase very much the cost of paint, a cheap interior varnish has been used, not in any way suited for the purpose. The ordinary house painter knows as little about varnish as the average astronomer, and his mixtures are not likely to give satisfaction to his employer any more than they would to a varnish expert. Another cause for lack of faith is that railway coaches, which are pro- tected by varnish, require frequent refinishing. This is because they are constantly being rushed through a cloud of sand, siliceous dust and cinders, mixed with condensed steam and coal smoke at rates of thirty to fifty miles an hour, and the surface is simply ground off. The wonder is that anything can be made to last a year. No passenger will willingly hold his hand out of a car window for five minutes. Nothing but varnish will stand it. Another case is in the use of spar varnish on a ship or yacht. This needs revarnishing every season, sometimes oftener than that. Since spar varnish is of good quality and intended for outside use this would seem to be a fair criticism. But it should be remembered first, that this is a very severe exposure, exposed to the intense heat of the sun reflected by the water; it is a case of continual wet and dry; and, finally, that the surface is frequently rubbed and polished by the sailors. Another and important reason lies in the constitution of the varnish itself; probably four-fifths of all the spar varnish made is used for what may be called repair work; every little while it is the practice to revarnish, and in these cases it is essential that the varnish should dry hard over night so that the vessel may go into use on the following day. In order to meet this condition the maker finds it necessary to make such a varnish thinner than usual, so as to secure a thin coat which will dry quickly, and, of course, only one coat is used. A varnish which would dry hard over night in a thick coat would be too hard and inelastic to be good. But if we are to compare a varnish film with one of paint we must allow it thirty-six .to.seventy-two hours to dry, and at least a month to harden, for that is what a paint requires, and a varnish can be made on those specifications which will cutlast any oil paint film that ever was made. Of course, no ordinary varnish is like that, but this is only in line with what has already been said, that a varnish must be made especially for the use to which it is to be put, and that the varnish maker who has the most knowledge of the subject will have the greatest success. A varnish film ts very much less porous than an oil film; the compound of oil and resin is far more indifferent to chemical action than oil alone, and as it possesses a very high degree of elasticity, it is, on this account, greatly superior to a spirit varnish film which consists of a brittle resinous sub- stance; it has, or should have, a substantial and appreciable thickness; it is hard and glossy, where an oil film is soft and spongy, and is in every way made more substantial; but the same pigments may be used in var- nish, thus making varnish paints or enamel paints, which are as much better than varnish as oil paints are better than oil. For marine exposures especially the writer's own experiments (see Transactions Am. Soc. C. E., Vol. XXXVI, p. 483, and Vol. XLIII, p. 444) have conclusively shown that varnishes and varnish paints are greatly superior to oil paints or red lead, while the baked enamels are much better than either. THE RACE FOR THE AMERICA'S CUP. A dispatch from Bristol, R. I., announces that every day during the week something new cropped out about the Herreshoff shops to denote that the work on the hull of the cup defender will begin in a very brie time. In the blacksmith shop during the week new chain plates for the shrouds were forged out, and the job of getting out straps and struts was begunalso. It is an early start on such work, but double sets of these things are to be made, principally the strappings which are to go in the interior of the new cup defender. The work of making the cup defender's sails is well under way. Two of the jibs to be used on the boat are now partly made. Foreman Hathaway has half a dozen sailmakers at work, - but probably as many more will be hired a month hence. It is learned from two or three different sources, most of which are reliable, that the members of the cup defence syndicate will contribute $50,000 each to back the enterprise of building the new boat soon to be begun. The total of $250,000 would indicate that the best of everything that money can buy will enter into the boat's construction. The announcement at the New York Yacht club headquarters that William Butler Duncan will manage the new cup defender gives general satisfaction, as it is recognized that Mr. Duncan's scientific attainments, his gentlemanly manner and his practical experience as a racing man will insure the cleanest of sport in racing for the cup. The Herreshoff boat shops and the different other shops that are auxiliary to the larger structures, have just had a new and independent electric lighting system established, which, no doubt, will be used to con- siderable extent between now and next May in aiding in the pushing of the work on the new yacht. _A Glasgow dispatch says: 'Of all the arrangements connected with the latest challenge for the America's cup there was none which gave rise to the same amount of indecision as the fixing of the part to be played by the first Shamrock. Her designer never quite lost faith in the boat, and Sir Thomas Lipton, in his anxiety to get the best possible boat which can be built in Britain, irrespective of all other considerations, was in- clined to invite Mr. Fife to make what alterations he considered advisable to the ex-challenger, and to have her ready for racing against the new boat which Mr. George L. Watson has designed. Against this there was the natural desire of many yachting men to see the Shamrock brought back as nearly as possible to her cup racing trim, so that the trial races between her and the Shamrock II. should give some kind of definite idea as to how the new boat compares with the Columbia. Sir Thomas Lipton viewed lboth of these courses with about equal favor, and it is only within the past few weeks that he finally decided to refit the Shamrock in her old form and get whatever advantage could be gained from the line which will thus be drawn between the form of the Shamrock II. and the Colum- bia, and, presumably, the new defender. The consideration which brought him to this conclusion was the report of Capt. Sycamore on the American boat. Sycamore was greatly taken with the appearance of the Columbia and his report was emphatic that, in his opinion, no amount of tinkering would ever make the Shamrock able to beat her. If this opinion was reliable, and if the Shamrock could not be made as fast as the Columbia. it was, of course, better that she should be preserved in her known form, and for this purpose she was towed over to Greenock and dry docked for examination. Her condition was an eloquent testimony of the ex- cellence of manganese bronze, for it was found that the underbody was as perfect and almost as clean as on the days on which she sailed her races. The aluminum was, however, in a sorry state where it was exposed to the action of the salt water. Right along the water line it was pitted with corrosion which went nearly through the plates. There was likely to be some difficulty and some delay in procuring plates of the same aluminum alloy to renew the damaged parts, and it was, therefore, decided to use ordinary mild steel for the job. Over the \bronze there were two strakes of aluminum plating forming the topsides. The under strake has been stripped off from stem to stern and steel plates have now been rivetted on. There was a difficulty in the danger of corrosion which exists when bronze and steel are brought together, and it has been sought to over- come. this by putting strips of canvas heavily coated with white lead be- tween the two metals. The only other alterations carried out to the hull were the fitting of a new taffra'l and the renewing of some of the internal struts which showed signs of weakness. Some little fittings will probably be added inside, and it is expected that the refitting of the racing spars and gear will then be proceeded with in time to enable her to go out for the Riviera season if sport enough offers. So far as the building of the new boat is concerned, the speculation now indulged in deals chiefly with the material of which she will be made. There seems to be a general beliei that he will turn out a boat composed largely or wholly of what may be described as fancy metals. COAL CONSUMPTION OF WATER TUBE BOILERS. The following from a recent number of Engineering, London, is of interest to American readers: / As our readers are aware, Messrs. Thomas Wilson, Sons & Co., Ltd., of Hull, have been experimenting some years with water tube boilers, and the engineering world has been looking anxiously to learn the result. The Pall Mall Gazette of Nov. 6 published a statetnent of the result, bringing out that, although there was a saving in weight of 100 tons when comparison was made with the ordinary cylindrical boiler installation, the coal consumption was so much greater--l6 tons a day--that 480 tons more had to be carried in the bunkers. In view of the repeated inaccurate representation of facts regarding the water tube boiler question pub- lished in the Pall Mall Gazette, we reserved judgment until the appear- ance of Messrs. Wilson's official statement, giving the accurate result, which indicates that not only was the weight of boilers less, but that the coal consumption on the voyage to New York was 100 tons less, and the speed 1.72 sea miles per hour more. We give the Pall Mall Gazette para- graph and Messrs. Wilson's letter in full: EXTRACT FROM THE PALL MALL GAZETTE, NOV. 6, 1900--THE COAL EATING WATER TUBE BOILER. "In the course of a debate last session on the. demerits of the water tube boiler as a steam generator for our large warships, Mr. Charles Wil- son, M. P., the head of the Wilson line of steamships, mentioned that he was sending his steamer Martello on a 7,000 mile trial trip, in order to test the comparative merits of the water tube boiler and the old cylindrical boilers which had been taken out of the same ship. Mr. Wilson claimed at the outset that a saving in weight had been effected, as between the cylindrical and the water tube boilers, of 100 tons, The Martello's trip has been completed, and we learn that the results have been most unfavor- able to the water tube boiler (which is not the Belleville). The coal con- sumption of the steamer, to produce the same results as the old cylindrical boilers, was higher by 16 tons a day, so that she burned on the trip 448 tons more coal than she had burned on a similar trip with cylindrical boilers. This represents so much more coal to carry on the voyage, and this 448 tons of extra coal completely swamps the economy of 100 tons in boiler weight saved. It is only fair to say that Mr. Wilson has a per- fectly open mind on the question. This test is an evidence of it." * EXTRAOT FROM THE PALL MALL GAZETTE, EXTRA SPECIAL EDITION, NOV. 8, 1900. "Editor Pall Mill Gazette: Sir--We notice a paragraph in your issue of the 6th inst., referring to our steamship Martello, in which you stated that this vessel burnt 448 tons more coal on her voyage since being fitted with water tube boilers than she did previously with ordinary cylin- drical boilers, : "This is quite incorrect; the coal consumption on her first voyage with water tube boilers being 100 tons less than the average of three years with ordinary boilers, and the speed is 1.72 knots faster, "We think, in courtesy to us, you should have given us the oppor- tunity of verifying your figures before publishing them, which we shall at all times be pleased to do, and we should be much obliged by your letting us know how you got this most inaccurate information. The ship is now on her second voyage, and we have every reason to believe that the performance will be improved. We may add that nine of our steamers are now fitted with Babcock and Wilcox water tube boilers." Yours, etc. - For THOMAS WILSON, SONS & Co., Ltd. (Signed) CHARLES H. WILSON, M. P., Chairman.