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September, 1913 inclined to the vertical, the forced oscillations when amongst waves were generally found to be equally in- clined to the wave normal and not to the equilibrium position. In the longer and flatter waves, however, there was a slight tendency to oscillate about an inclined position, which was very near to the wave normal and never so much inclined to it as the still- water equilibrium position. The total oscillation in these cases was always small. It is conceivable that in very long flat waves the oscillations may be about the equilibrium position, but in the shorter and steeper waves the internal water rushes across from side to side and the rolling takes place about the wave normal. 58. As the quantity of water in- efeases, so the curves of angle foll for constant wave length get steeper for an increase of wave height. With 5.87 per cent of water on waves 600 ft. long and 35 ft. high, the motion was extremely violent; the water simply rushed in a foaming cascade from side to side, and the least dis- turbance only increased the effect. 59. Synchronism should take place at a wave length of about 750 ft., but it will be seen that the maximum an- gles reached will be for a much short- er wave. Upon timing the model, however, it was found that the period for an oscillation of 36 deg. was only 1.25 seconds, so that it is evident that the maximum angles are affected by the periods of roll for large angles, which one would expect to be the case. : OO. Referring to Figs: 20 to 24, it will be seen that, generally speaking, the addition of free water decreases the angle roll. In the short- est and highest, and therefore steep- est, waves, however, the effect is to increase the angle of roll, so that the forced oscillations are even great- er than the maximum oscillations with no free water. This effect seems to be produced by the synchronism of the period rush of water across the vessel and the period of the wave. There will be a certain combination of wave length and height--i.e, a certain wave steepness that will pro- duce just the critical period for the Water to rush across. When this takes place, the angle of roll may be very large. Further, these angles are Teached in a very few rolls, and have been reached when starting from Test. It is, therefore, quite possible that dangerous angles may be reached in actual ships, where the vessel may have an. initial heel and roll, although the resistance to roll may be very great. 61, other hand, #. the On "the THE MARINE REVIEW quantity of water be limited, the an- gles reached are always smaller. This points to the efficacy of anti-rolling tanks having small water capacity for the safety of ships. 62. A great deal of work remains to be done on this very important subject. It is one of very great prac- tical importance, especially in view of the growing tendency to adopt free water as a means of reducing rolling. It is proposed to carry out a similar series of experiments with anti-rolling tanks, with a view to find- ing out experimentally the actual ef- fects of such tanks upon the maxi- mum angles of roll. Till such work is systematically done, we cannot be sure that in all circumstances anti- rolling tanks will reduce rolling. It is hoped that this paper will stim- ulate interest in the subject. Success of North American The steamship North American, which was built by the Great Lakes Engineering Works for the Chicago, Duluth & Georgian Bay Line, of Chi- cago, has enjoyed a season far be- yond the expectations of her promot- 339 ers. The steamer has apparently sprung into instant popularity, as she has car- ried a full complement of passengers on each trip. The steamer carries no freight whatever, being devoted wholly to passengers. She makes a round trip each week to Lake Michigan, the Straits of Mackinaw, Georgian Bay and Lake Superior, and it is quite likely that the company will later on place an order for a duplicate. Prof. E. E. Haskell, dean of the school of engineering, Cornell uni- versity; W. J. Stewart, chief geog- rapher of the naval service depart- ment, Ottawa, and V. W. Forneret, superintending engineer of the St. Lawrence river ship canal, have been appointed a board to investigate and report to the minister of marine of the Dominion government on _ the whole question of water levels of the St. Lawrence at and below Mon- treal. i Col. William T. Rossell has been appointed chief of engineers, war department, vice Brig. Gen. William H. Bixby, retired. SUMMARY OF NAVAL CONSTRUCTION. Per cent of completion. Aug. 1, 1913. July as : e of Per cent er Cen Myesel a Contractor. Total. onship Total. on ship. Battleships :-- New. York... .2.5 22; New York Navy Yard...............-. 85.8 84.8 83.3 82.0 Texas: ee. Newport News Ship Building Co........ 9137 90.6 90.6 oo Nevada 232. Fore River Ship Building Co............ 40.3 20.1 Sak ie Oklahoma. ¢ 20.3... New York Ship Building Co............ OLh 27.4 33.0 ao Pennsylvania ~...... Newport News Ship Building Co........ 2.0 0:5 1.4 ; Destroyers :-- Cassin. ei ee Bath. Tron Works =n. se og ss wee pe 99.3 ae ea: ace Cummings =...2.7555:. Bath Iron. Works ............eeses eee a e. eae a OWNES geese ce: New York Ship Building Co............ 63. 61. re 2 Duneans.si52.2 Fore River Ship Building Co 98.0 cs a ae Aylwin sonar goes ae Wm. Cramp & Sons oe i on a Parker 233. Wm. Cramp & Sons aS uo oo ae Benham? 220.6055 4. Wm. Cramp & Sons oe ae ae ave Balch. See: Wm. Cramp & Sons - i ee 3 O Brien ee Wm. Cramp & Sons a Le oe Nicholson . Wm. Cramp & Sons A oy 3 Winslow = 3.3. 2... Wm. Cramp & Sons ae vse ae McDougal os. .4.55: Bath Iron Works... .......sseeeseeeeee ae a ae a Cushing. .24 co Fore River Ship Building Co........... oe a "e a Hricsson 442. st ew "York Ship Building Co..,:....... : : : : bmarines :-- : G-4 ae ROG pes aes American Laurenti Co, (Phila.)......... 93.4 oo a eo Ged oe eee Lake Tow Boat Co. (Bridgeport) eer es 88.1 88. , : Fed a ae ee Electric Boat Co, (San Francisco)...... 94.5 94.5 94.5 ore He ee Electric Boat Co. (San Francisco)...... a ane a ae Hg ee a eee Electric Boat Co. (Seattle)...........+. ao oe ae a GB eee ie ee ae Lake Tow Boat Co. (Bridgeport) grease os oe co oe Keb ae Electric Boat Co. (Quincy) ........+++- ao a ae a Kee re Electric Boat Co. (Quincy) ........+++- oe a ee ae Kie3 Sok eee Electric Boat Co. (San Francisco) ..... i oe oe oer KA oe ee Electric Boat Co. (Seattle) .....-..++-- ae ae ee fe. K5 ee Electric Boat Co. (Quincy) «....++++e+s a aoe one a K-66 Ga ees Electric Boat Co. (Quincy) .....-.5- Se oe a aS Te] oe es aa Electric Boat Co. (San Francisco) ..... a as see ke KS es veges Electric Boat Co. (San Francisco) ..... oe ea! ae Oe Te ee ae Electric Boat Co. (Quincy) ....+++++++- a ae poe nee E222 a ee Electric Boat Co. (Quincy) ....+-+++++- ag s ve a Li- 3) eee ee ees Electric Boat Co, (Quincy) ..++..+++++- oe ce ee ee Ti40 ee e Electric Boat Co. (Quincy) ...+..+++--- ae a ane he Dik Lake Tow Boat Co. (Bridgeport)....... f an oe ae Leb Lake Tow Boat Co. (Long Beach, Cal.) 00.0 00.0 00.0. 00.0 Lo Lake Tow Boat Co. (Long Beach, Cal.) we ap pe oie M-1 oe elie Electric Boat Co. (Quincy) ........<..- : : : ; nari ers :-- z Mia pet New London S. & E. B. Co. (Quincy). 14.3 5.8 13.4 5.5 Fuel ildi * " 97 oo? Boa Newport News Ship Building Co54 4s : alia ee Ae Newport News Ship Building Co....... 93.6 00.0 or os Jupiter. s<c..<2-2 +5 Mare Island Navy Yard........-++se++> a oo > ] Kanawha (<.--sse<<- Mare Island Navy Yard........--+s+0. ve ie a ie Maumee ...-.-+-++++> Mare Island Navy Yard.......+++.++++- : ; ; Gon Be wa Camp & See 45.3. 304 25.45 103 ee te ce Se ete 54.0. Skg 527-9 ne OnOeRey = 5 atace. Inland Mave Ved 2c. ae 54:0. SL *Delivered at Norfolk, Va., July 5, 1913.