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6 MARINE REVIEW. Twenty-foot Channel Work--Detroit Matters. Special Correspondence to the MARINE KEVIEW. Derroit, Micn., July 9.--Gen. Poe says that on all but one or two sec- tions of the 20-foot channel, work is progressing satisfactorily. Although this is a big job of dredging, which was taken by the several contractors at a cost scarcely more than half what was expected, the results of two months' work have justified the belief that it will be completed within the short time allotted to the contractors, and that when it is finished it will be the cheapest channel - work, in proportion to the benefits to be received, ever undertaken by the United § ates or any other government. Detroit people take a great deal of interest in the world's fair steamer Columbus, on account of her machinery being the product of Sam]; F. Hodge & Co., and they expect to see her develop a speed of better than 185 miles an hour, but they are not rash enough to credit her with 23 miles. The run' from Milwaukee to Chicago was not, they say, a fair trial as she was in fog during a large portion of the time. With more favorable conditions it is claimed that she will surpass any speed as yet rightly credited to her. The shallow channel between Chicago and the fair grounds will not permit of high speed with the boat, as she can not be sunk deep enough into the water, but it is understood that she will make a few trips down to Buffalo, Cleveland and Detroit during July and August, and if such is the case an opportunity will be found to give her a fair trial. It is also said here that it is the intention of the owners of the boat to run her between Detroit and Cleveland next year in opposition to the Detroit and Cleveland Steam Navigation Company, but this is of course, a matter of the future which would certainly involve some impor- tant alterations in the whaleback passenger boat that are not as yet made plain, At the Orleans street yard of the Detroit Dry Dock Company, cabin work on the City of Mackinaw, the second of the Detroit and Cleveland Company's new boats,is being pushed very rapidly and she will be ready, shortly after the first of next month, to join her sister ship, the much praised City of Alpena on the Detroit-Muckinaw route. These two grand side-wheel steamers have been a little behind time in getting into commission, but when it is considered that each of them has 150 state rooms and cost about $300,000, the dry dock com- pany has made a wonderful record in delivering them a week or two after the few months allowed for their construction. With all its valuable river front property, Detroit is only now in posses-' sion of a fire boat. The craft was given a place in the naval procession that welcomed the Columbuscarayels here a few days ago and gaye an exhibition of her water-handling power during the exercises. Her equipment in this re- gard, which was furnished by Thomas Manning Jr. & Co. of Cleveland, is un- doubtedly as efficient as anything of its kind in the country, and the commis- sioners are yery liberal in their praises of it. S$. F. Hodge & Co's. new shops are nearing. completion. The machine shop and the annex for erecting purposes are model structures. Both will be equipped with powerful cranes. Galleries for small tools on both sides of the machine shop add greatly to the conveniences for rapid work. A railway switch will be run directly from the machine shop into the foundry and within reach of cranes in both shops. Canal Tolls--Pushing Work at the Canadian "Soo." Special.Correspondence to the MARINE REVIEW. Kineston, Ont., July 6.--The Review is guite correct in its statement "that the Canadian government has no hand" in the reported refund of tolls on grain transhipped into St. Lawrence river barges. The forwarding com- panies say no refunds have been made and inquiry at the canal office develops - the fact that the publication is "an absurd yarn." The Montreal Gazette puts _ Canada's attitude in this brief form: 'The Canadian government does not resort to subterfuge, and when its canal to!ls policy is changed the whole world will know it." ee 'The government boiler inspectors have been ordered to detain all steam yachts found in use without having been subjected to the necessary inspection. Hitherto this requirement has been overlooked inthe case of small steam yachts but it will be enforced hereafter. Quite a number of yachts have been held at Ottawa for inspection, : The contractors of the canal at Sault Ste. Marie, Ont., are rushing the work forward. There are 70,000 yards of mason work to be done, but it is being put up at the rate of 5,000 to 6,000 yards a day. The subsidiary con- tracts, howevér are yet to be let for the gates and a swing part to the railway bridge. Itis probable that the workings of the locks will be by electricity as experiments are now going on at the Beauharnois canal to demonstrate its practicability. The power will be generatad at the "Soo" rapids, which the coutractors now use for the compression of air for drilling and doing other work. Freight rates on coal from Oswego have advanced within the past week and are now quoted 30 cents a ton to Kingston, 35 cents to Toronto and Ham- ilton, 5d cents to Toledo and 95 cents to Chicago. There isa strong demand for vessels, as dealers are anxious to get their stocks in before the price of coal advances. s British charts of Lake Superior cover the entire north shore, We haye them for sale at $1, . Steel Ship Construction.--Part, Ill. STRENGTH AT WATER-TIGHT, ACROSS-SHIP BULKHEADS. The rivets in angle frame bars which connect bulkhead p'ates to chell plating are spaced closely, so that the angle"bars may be properly caulked and made water-tight. In doing this the metal in the shell plating is reduced at a cross section. To pick up this weakness, liner plates sre fitted between the in- side strakesof the plating ou the inside of the vessel, as shown in the plan on keel and strakes'B, D, H and 8. MINIMUM SECTION OF METATL. wee River eae . PARTS OF THE STRUCTURE. Toray, H OLES, Er! ad ae Square inch. | Square inch. | Square inch. EID neers teeth aes has cacti deeee >.< 37.50 6.75 30.75 me ies PMG sae Nels eels niece ts san 03.00 3.179 29.25 Ae Sirake: Aa AT 66.00 10.50- = 59.90 Re ert eae cade bee ata aoce tare. 59.12 8.72 46.40 Ieee te NAC Wee etre sen cle cererer ameter mreiion> 47.25 Pie AOS: 40.05 CATES. SUR TELA Tihs cedars 52.50 8:72 43.7 Depa icine: cee stosec: Riss: Pare P tend gentle 64.00. 10.50 53.50 eee = MGR agen csievreadsh saci octets a 54.00 o.00. 45.00 De grt har neato dn seaeonmer oscaeas deat 52.50 7.86 44.64 Teltig ils ra recsacafranae ts ancy tpg a oiune tenons 39.38 6.42 32.96 deren PeslINVON ye acts sess iet osc eee eee 31.50 5.20 26.25 eet eRe ci cuigts cater sndec senses 52.00 8.25 44.76 Seer CeIn i aioay ants canbe Teor ien duets ~» 68.50: 9.00 49.50 Seeeaese ALTO Mees Sain cee cian as aiiae at 28.50 26.75 21.75 Center keelson ....... fa aera eieaan' ase 31.63 | 11.16 20.47 Girder No. 1...... Meee sPands dames Otar ss nee 19.50 2.81 16.69 Uae NIG REDE 2 as sated eituaos (oes asian 17.62 ~~ 2.84 15.28 Mee NO cape secs semet sce cctesiseMeag aes 15.74 1.87 13.87 Tank margin and angle................. 40.25 6.18 34.07 oe eee LOD UAL INI O MAN ya snencseconeeeneet 32.00 4.24 27.76 ey Ge cae oth cceeeua es ane 30.00 5.06 One gee Geers Ue Om corner reer 28.12 4.24 23.88 PS eT TICE PIALOy, tas 20s. ac anecod a 20.25 2.81 17.44 . Deck stringer and angle............. fe 71.00. 12°25 58.75 Abe. DIALING AL Garnatinount esse Meta: 15.00 1.56 ~ 13.44 ee oe Ar a Deiat adaires (geek eet 30.00 3.12 26.88 Be Sh iaceas CBr spac sa4 EP apticase ry eee 30.00 3.12 26.88 . Side stringers and angles.......... Sree [ta 49.50. 18.36 31.14 Wew@er pars aieit Ghee en ere os 18.00, 2.50 15.50 MOtalin vee Uae ren tats 1,125.86 190.29 935.07 The rivet holes are punched 43 inches apart in the shell plating, girder, side stringers and center keelson, 4 inches in the tank top plating and 6 inches, center to center, in deck stringer and deck plating. Center keelson, girders | and side stringers pass through bulkheads. 'The punchcd* material in this in- stance is 985.07 square inches, being 138.91 square inches greater than at un- avoidable weakest section ; that 1s, supposing the shell plating and liner will give way. It is not likely that both plates will brcak but that the shell plate will, end shear the rivets in liner shown on one side of buikhead. The punched material, after deducting the area for punched liner plates, is 772.69 square inches, being 25.57 square inches, or 707.10 tens, weekcr then at a line through the rivet holes ata frame. In order to overcome this weakness, a number of rivets must be put in the liner plates on each side of bulkhead equal to 707.10 tons, the liner plates acting asa butt strap, The shea ing strain of a {-inch 2 " ButkHv£aa BAR Viste... ce e@ °° 8@ 82 69 8 oe f8 ao nos iron rivet in a steel plate is 8.4 tons, so that 85 rivets would be the number re- quired on each side of the bulkhead to c my} ensate for the close pitch of rivets. This arrangement of liner plate has 110 rivets, which is equal to 924 tons, the strength over the weakest section Leing 216.9 tons. The tensil strength of a j-inch rivet is fourd by squaring the diameter and multiplying by ,7854 for area and by tons per square inch. Example--#/'x8//x.7854x22 tons=10 tons, nearly. Ten tons is taken for the tensile strength ofa }-inch rivet and the same for shearing strength when connecting iron plates. If the girders and side string- ers stop on each side of the bulkhead,then the strain comes on the rivets when the vessel is resisting tensioii at these parts, Should the girder and stringer plates not be properly fitted to the bulkhead, then the rivets would be strained when compression occurred. The angle irons which connect the longitudinals to the bulkhead should be equal in strergth to the ' 5 plate, and the holes for rivets should in no case be less than one inch from the edge of angle bar A number of rivets should be put into the ends of the girders and side stringers equal to the strength at we akest part of these longitudinals.