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BOILERS, From the Naval Annual. The past year has been characterized by a persistent discus- sion in naval engineering circles, and in the technical press, as to the relative merits of the various types of water-tube boilers in use in the navies of the world, and, to a much more limited extent, and more especially in England, to the relative merits of water-tube and cylindrical boilers. In most navies the cylindri- cal boiler seems to have been definitely and entirely abandoned, except in partial installation in large vessels in conjunction with water-tube boilers. This compromise arrangement has found much favor in Germany and has been used in Holland, and is to be tested by the British admiralty. The numerous tactical and constructional advantages of the water-tube boiler over the cylin- drical have been so often stated that it would be superfluous to enumerate them here. 'There is a conservative element in Great Britain that has consistently upheld the cause of the cylindrical boiler for use in the British service, and these took much heart from the result of the Hyacinth-Minerva trials last summer. But as to actually settling the vexed question the results of these famous trials would appear to be unsatisfactory, for, though they showed that the Scotch boilers of the Minerva were super- ior to the Hyacinth's Bellevilles, the tests did not prove that the Scotch boiler is superior to other types of water-tube boilers, but simply seemed to confirm what the previous trials had shown--the special faults and deficiencies of the Belleville generator. : Ui course a section of the English and the continental tech- nical press, and world, did not accept, without much protest, these results, and made claim that much of the lack of success with Belleville boilers in the British service was due to unskill- ful care and operation by the personnel. That there may be ground for this claim is shown by more successful experiences with Bellevilles in other British vessels, and particularly in the trials of the new cruiser Good Hope, though it has by this become well known from sad experience that the performances of a vessel's boilers during trial trips, even of an extended nature, a no criterion of their subsequent: behavior under service con- itions : France, Italy, and other naval powers have been using Belle- villes With SaliSiactory resuits during tne past few years. While the British admiralty were evidently justified, from the evidence before them, in condemning the exclusive, or even extended, use of the Belleville in their service, the engineering world in genera! feels that further exhaustive and long-lasting trials in competition with other water-tube boilers are essential before this system can be definitely condemned or placed in its proper ~ position in a relative scale of merit of the various types. Ger- many and Italy have both engaged in such tests, accounts of which are given further along in these notes, and Great Britain 1s now, as befits the much greater size of her navy and her vital interest in such matters, about to carry out comparative trials upcen the largest scale yet undertaken. 'he results of these. trials will be watched with the very greatest interest, for the prob- lem is still very indefinite, and the net results of investigation to date force us to the conclusion that though the water-tube boilers are superior, indeed essential, for our new vessels, yet each of the types in use has its own special defects and disadvantages. The problem would appear to be to find the boiler that has the least of such faults, or, better yet, to set about eliminating them in the present systems, or to discover an entirely new type that shall be free from them. Water-tube boilers may be divided into two general classes--- small tube and large tube. There has been controversy during the past year as to the relative merits of the two types for use in large vessels. In the small-tube type we have straight or bent tubes of an inch or so in diameter connecting water pockets at the bottom to a cylindrical steam drum at the top. This type has been almost universally used in all navies for launches. torpedo boats, destroyers, in many ecun boats, and in small cruisers, and in France, Germany, and some of the smaller navies to a greater or less extent in large vessels. The Yarrow, Thornycroft, Thornycroft-Schultz, Norman, Normand-Sigandy, Normand, and Guyot, are the principal boilers of this type. The smaller tube boiler first came to life about twenty-five years ago, Owing to the demand then for higher speeds in torpedo boats. It is a very light boiler, which can be forced to an extent that other steam generators can not. It has practically enabled the modern torpedo boat destroyers to attain their great speeds; but the life of the boiler is very short, the repairs required very great, and the skill in handling very considerable. These sacrifices are only what can be expected from a boiler designed' to drive such frail craft as destroyers. 'Their average lifeis about two or three years in such racking service, but there are several new boats lying in the dock yard reserves that have had to have their boilers retubed in spite of only having recently been built, and never having steamed except on their trials. This is due to the decay that goes on inside the tube while the boilers are idle, and as the tubes are very thin they consequently can not afford to lose very much in thickness. The general tendency lately has been toward the elimina- tion.of the small tube boiler for large vessels, owing to the MARINE REVIEW AND MARINE, RECORD, ~ 29 known difficulties in cleaning them and to dangers in operation: However the French and German admiralties have by no means entirely abandoned them, though there have been a series of most unfortunate catastrophes and failures with small tube boilers in both services durine the past year. The distinctly adverse opinion of the British boiler committee with regard to a class of generators in large vessels was a decided setback for the type. , ms eo The large tube boilers, now the subject of so much contro- versy, consists essentially of a group of more or less inclined straight tubes which are jointed to a single or series of vertical collectors, which connect a water collector at the bottom to a cylindrical steam drum at the top. The tubes are single, of the ordinary type, as in the Babcock-Wilcox or Belleville, or of the double or Field type, as in the Niclausse or Durr. - These four are the leading types of large tube boilers and are those with which the principal experiments are now being conducted abroad. The new type of Yarrow boiler which has found favor in Hol- land and Austria might be said to be a compromise, for, while it retains the general constructional arrangement of the small tube type, its tubes have been made much larger than formerly. Following will be found notes upon the system of boiler installations in the principal navies with recent experiences in operations and trials. The South American powers, which pos- sess a number of large and important vessels, have in every case had them constructed in British or European ship yards and have adopted the particular type of generator most in favor at the various ship yards, so they have formed no consistent naval boiler policy. AUSTRIA. After making rather unsuccessful_trials in the Lussin with the earlier type of Durr boiler, the Austrian government adopted the Belleville and Yarrow boiler, and at present they seem to be about equal as to preference. DENMARK, - This government has installed the Thornycroft small tube boiler in its new coast defense ironclads, following the result of an installation of eight boilers of this type in 1898 in the small cruiser Geiser. ; FRANCE. The French admiralty have passed through a year of much doubt and uncertainty in regard to boilers, and nowhere has the question of small versus large generators raged more furiously. Almost the first to install the water-tube boiler, France has for a number of years committed herself absolutely to the type. Asa consequence we have more types originating in France than any other. country, and the French navy has made trial of five sys- tems. 'These are Belleville, Lagrafel-d' Allest, Niclausse, Guyot, 'and Normand-Sigandy. The Lagrafel-d' Allest, a straight inclined-tube boiler, the tubes being dudgecned into large single headers at front and rear, was early condemned in consequence of a serious accident with this type on the Jaurequiberry, and because of the great care required in working them. Before their abandonment, however, they were fitted into a number of important French vessels. The Belleville and Niclausse boilers have been very exten- sively used. 'The former, having been on the market for a longer time, has a greater total of indicated horse power in use than the latter. Recently the orders are about evenly distributed between them. One hears very little complaint from French .navyal engineers as to their operation, and in fact, considerable praise as to the ease with which they may be cleaned, cared for, and repaired. A The Guyot and Normand-Sigandy boilers of the small- tube type have been installed in a number of French' vessels, including some of the largest and most important cruisers in the service. Among others are the Jeanne d'Arc, Chateau-Renault, Montcalm, and Jurien dela Graviere. These vessels during the past year have undergone an unfortunate series of trials and mishaps, which have done much to destroy faith in the small tube boiler. rie The Chateau-Renault had her trial last August, at which time she obtained, in a three-hour trial, the splendid speed of 24.2 knots. ape 3h As far as can be learned, during this trial the boilers functioned satisfactorily, and the -faults developed were .all in the engine room. During a six-hour trial this vessel de- veloped 18,500 H. P. at 118 revolutions, giving a speed of 21.5: knots, with a coal consumption of 1.423 lbs. per horse power hour. These results are excellent. : The Jeanne d'Arc was taken out for her first trials the latter part of July. This 11,000-ton cruiser has Guyot boilers designed to furnish 28,500 H. P. for 23 knots speed. T'wenty- four out of the thirty boilers were started up. Almost at the beginning it was found that coal could not be directly thrown into the furnaces, but must be put in from one side. The temperature in the fire rooms rose to 155° F. The water feed began to fail and the boilers became red hot. 'The fire- room force abandoned the stokehcles in a panic, fearing 'an awful catastrophe, and they were only driven back in order to draw fires in six of the boilers which were at a red heat, and fourteen in which the water level has disappeared. With the remaining four boilers the vessel crawled back into port at a speed of 2 to 3 knots. In consequence of this accident the installation is being extensively overhauled, and the vessel will