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326 ing the difficulties which presented themselves. Condensers. The obtaining of as perfect a vacuum as possible being a special factor in steam rotary engines, the question of an efficient condenser becomes all import- ant, and it is remarkable that almost simultaneously with the coming forth THe Marine REVIEW 6 fractures, and even when no fracture took place, caused unnecessary expense by the frequent drawing of the shaft inboard for examination, has of late become more satisfactory by the adop- 'tion of long continuous gun-metal liners or casings. The latter prevent al corrosive action in the portion of the shaft not visible, and the revised rules for diameter have also insured ample Table II. '. a ae S. cet w a Ele Diam. of Cylinders. 3 as : ; Oe eG o J S ' z aM : 8 bo > gee a ss S o a . Ss SG s o oD % oO G nm 4 aA 4 2 oon. (RP Me IP a 6k eee : eee aes cae 465.4 60.3 31.3 24% 39 48 = 39 200 3 tobe Gan Ge ese ai 460.7 60.2 31.3 2o0f 24% : of 41% 20f69 48 none i. : 1905 3C Ati os ee ee 650.4 72.2 40.0 urbine ne Cee 1905 Girone eee sas 650 72.2 40.2 39 54% Ta. 110 66 none 210 2 1909 Laurentie 3. 6.2 ees 550 67.3 32.9 20f30 2 of 46 2 40f53 54 none 3 1909 Megantic ......,... 359 6733 32:9 20829 2of42 -2 of 61 -2.0f 87 - 60- none Z were made to improve upon the ordi- of the turbine the first real "tach being given to nary surface condenser existing since ' the days of Hall, who introduced it in 1831, and actually had it fitted on the paddle steamer Sirius, in 1837, and on the early Atlantic liner British Queen, in 1839. After considerable study and experimenting of the con- denser prob!em, it is a matter of com- tnon knowledge that it is only a few years ago that this question was given the great consideration which so im- portant a matter deserved. After con- siderable study and trials, most inter- esting results were obtained by D. B. -Morison, who, acting in conjunction with Prof. Weighton, succeeded in dis- covering hidden defects and placing the designs of condensers, contraflo and others, on a satisfactory footing, and fully explained them in various papers read before kindred institu- tions. These itmproved condensers, with the addition of the modern im- proved air pumps and the vacuum aug- mentor of Mr. Parsons, have insured satisfactory working and have helped to hasten the adoption of the tur- bine, Shafting. Owing to the adoption of balanced- piston engines and the turbine princi- ple, the shafting of modern vessels has now a'most ceased to be the source of anxiety and trouble known in the past, the shocks and uneven straining being almost altogether eliminated, so that it is unnecessary to comment upon this section of marine machinery, with the exception perhaps of the after-length of which the propeller is directly placed. This shaft, which formerly gave such trouble by frequent withstand the rough usage to which this part of screw-propelling machinery is so _lia- ble, owing to variation of draught of vessel and the violent racing and strain- ing in heavy weather. Propeller. With regard to the propeller itself little can be said,as the design and style of construction have now settled down to recognized types for the various classes of vesse's. Notwithstanding the nu- merous papers read on the subject and immense sheets of formuiae and dia- grammatic exposition given it, it is yet only by trial and result that the best propeller can be found for each vessel, and the recent alterations made in the blades of the two great liners Lusi- tania and Mauretania, serve to recall the doings of his majesty's steamships Iris and Mercury, in 1878-9, when still more startling and unexpected results were obtained. Boilers, Coming now to the steam generator, and looking back since the last time marine engineering was brought before the institution, in 1901, by Mr. McKech- nie, it is not possible to note any ad- vance or change in the design, as no marked a'teration has taken place; but the improvements in the manufacture and working of larger boiler plates have resulted in the still further reduction of riveted parts: As an instance of how extensive the modern boiler shell- plate has become it may be mentioned that the largest plate yet rolled meas- Wires: 42 ft. by -9 ft) 6 in. by 1% in. thick and weighs close on 11 tons. Strange to say this plate is not fitted on one of the most powerful liners, September, 1 but on a moderate-size Mersey tugboat named the Knight Errant. The intro. duction of automatic circulators, fitted inside the boilers without any Working | parts whatever, has materially reduced the repairs rendered necessary by the abnormal strains set up by the vary- ing temperatures prevailing in different parts of the boiler. In considering this question of boilers, one must not omit to call attention to the still further advantage to pe gained by the adoption of turbine mma- chinery, owing to the fact that lower steam pressure is required. What this means in saving of weight over the scantlings necessary for the boilers of quadruple and the later triple-expension piston machinery can be fully realized, when it is considered tha: in the case of the Lusitania and Mauretania the saving in weight on the boilers alone is about 120 tons over and above that which would have been' required if triple or quadruple piston engines had been used. This also aoplies in the case of the cross-channel vessels, such a the Isle of Man steamer Ben-my- Chree, to be seen at the Liverpool landing stage, the scantlings in this vessel being something like 75 tons less weight than would be required for piston machinery of equal power. To the naval architect this gain of weight presents a pleasing factor, enab- ling him to provide further luxury or want demanded by the exigencies of modern travel. Mechanical Stoking. A detail of considerable importance to the boiler room is that of the adoption of mechanical stoking of some description. This, like other sub- jects, has been the cause of numerous experiments and patents, but so far it cannot be said to be so satisfactorily solved as to insure universal adoption, although the Henderson system has been largely used. The fairly wide adoption of forced draught has, how- ever, increased the difficulty, and_ this is much to be regretted, for there is no doubt that the want of some sys- tem is badly felt which cou'd modify or completely do away with the ar- duous requirements of the stokehole of all steamers, at present so trying, and one may say so debasing, to hu- manity. When one conjures up the scene on board of a large liner where upwards of 1,000 tons of coal are consumed in 24 hours, every ton of which has to be manipulated by the firemen and trimmers in temperatures rising sometimes up to 12) deg. Fahr., the great want of mechanical con- trivances is fully realized, and it is