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20 moved, and the cover lowered into posi- tion, thus making the .hold gas-tight. Under these conditions the most-danger- ous cafgo could with safety be carried in an atmosphere of carbon dioxide, as there would be nothing to cause or sup- port combustion, and should gas be gen- erated from a coal cargo, so as to create pressure in the hold, it would blow the light water-seal of the hatch cover, and so relieve the pressure. In this way, not only coal, but crude oil, petrol, and any dangerous cargo could be carried with- out risk. ; On reaching the port of discharge the hatch cover would be raised, and air from a blower forced down through the hose, escaping as low down in the hold as possible, and this, after an hout's blowing, would mingle with and displace | the carbon dioxide, and any gas that might have been :formed, and when a safety lamp lowered into the hold burnt brightly, it would be safe for men to descend and 'commence the discharge, the air current being kept going all the time. I am quite aware that the difficulty of making a bulkhead watertight is consid- erable, but I have too much respect for the engineering skill of the members of the institution to even suggest that it. is impracticable, and if the big carrying lines had one or two vessels so fitted for the carriage of dangerous cargo, they would easily recoup the initial expense. -The amount of gas needed to fill up the space not occupied by cargo would be comparatively small, and although the supporters of existing systems would talk of the langer of leakage of the gas into the working and living parts of the ship, such danger is practically nil. Any such leakage would be brought about by straining of the bulkhead during heavy weather, and the liquid would have to leak out before any gas could escape, which would probably lead to the detec- tion of the trouble; but, even if this were not so, there is no danger in the slow leakage of the gas, as it would practically escape by diffusion, and the increase in quantity in the living portions of the ship, even under the worst conditions of venti- lation, would be extremely small, and as candle and lamp flames are extin- guished before health is affected by mix- tures of carbon dioxide with air, should a serious leakage occur, attention would probably be called to it by this fact. In passenger vessels, chemical extinc- teurs, which throw a mixture of saline solution and carbon dioxide, would be of great value for extinguishing small fires occurring in bedding, draperies and fittings, but they have not been adopted because, as ordinarily made, their use necessitates the carriage of mineral acids; it is, however, perfectly easy to THe Marine REVIEW make them without the use of objection- able acids, and so obviate this trouble, whilst 'the use of 'non-flammable wood for all fittings: would' give a degree of safety never yet attained. In conclusion, I have to apologize for the length to which this paper has ex- tended, and to hope that some points ok interest and use may be found in it by those desirous of decreasing the risks of the sea. DULUTH-SUPERIOR COM- oe MERCE. Major Graham D. Fitch, government engineer, has just issued his report of the marine commerce of Duluth and Superior for the calendar year 1907. July is usually the heaviest month of the year, but in 1907 it was less than June and August, the cause being the labor strike in the iron ranges which stopped shipments of ore for 15 days during July. Hard coal shipments show an in- crease of 280,455 tons over 1906, and soft coal an increase of 1,432,184 tons. Iron ore shows an increase of 4,222,783 tons over 1906. Wheat and other grain shows a decrease of 6,239,442 bu., with an increase in valuation of $11,916,161 over 1906, due to the higher prices prevailing for all kinds of grain dur- ing 1907. The average number of tons of freight shipped per day from Duluth and Superior was 115,166 tons. The navigation season covered a pe- riod of 234 days. This is reckoned from the first departure or arrival to the last departure or arrival to or from the lower lakes. It is understood of course that the open season for Duluth-Superior harbor to and from Lake Superior ports only was much longer, some local boats running all but two months of the year. The largest cargo entering Duluth-Superior harbor was carried by the steamer W. M. Mills, consisting of 12,680 net tons of soft coal. 'The largest cargo leav- ing the harbor was carried by the steamer Wm. B. Kerr, consisting - of 137i2° met tons. of iron ore: The largest cargo of grain was carried by the steamer L. S. DeGraff, consisting of 422,000 bu of wheat, weighing 12,660 tons. It is interesting to note that there is a large increase in tonnage but a falling off in the number of ar- rivals and departures, showing clearly how fast the smaller craft is being re- placed by the larger. The first boat to enter the harbor from the lower lakes arrived on April 26, being the first of a fleet of 136 boats which had been imprisoned in the ice in Whitefish Bay at the east- ern end of the lake. Major Fitch ac- companies his report with a photo. graph showing a large number of the vessels of this fleet at anchor in the harbor basin awaiting their turn at the docks. The total receipts of Duluth. Superior harbor were 7,840,023 tons, . valued at $95,702,839. The total ship- ments were 26,946,682 tons, valued at $191,826,855. CALENDARS. S. Hemmenway & Son, 54 and 55 South street, New York, the well- known firm of sailmakers, are distrib- uting an attractive calendar to the trade, upon which is a. splendid re. production of the painting, "Sun. down," by W. E. Norton, the suc- cessful depicter of marine subjects, "Sundown" shows a parcel of mer- chantmen off Boston harbor. In. the foreground is a schooner-rigged ves- sel, while behind her, the setting sun showing red upon her -prow, comes one of the old square-rigged ships which some 100 years ago carried the commerce of America to every corner of the globe. One can almost feel the cool breeze over the sea and the swish of the water along the sides of the vessel. The 'Ashton Valve Co., 271 Frank- lin street, Boston, Mass., have just put out an attractive calendar on which they incidentally advertise their high grade pop safety valves and steam gages. The pictorial part of the calendar is entitled "The Winner," and she certainly is. This is a copy- righted photograph by S. S.. Porter of a girl in a yachting suit: steering a yacht. It is. one of the rare in- stances of a really beautiful pictorial effect being obtained by the use of a living model. Major: H. Jervey, government engi- neer at Mobile, Ala., recently opened bids for the construction of two wood- en hull stern-wheel snag boats for use in his district. The bidders were: Gulf Dry Dock Co., Mobile, Ala. .$38,500 J. M. Hammitt, Marietta, O....2 41,200 E. J. Howard, Jeffersonville, Ind. 38,000 Contract was awarded to E. J. How- ard. The general dimensions of the boats are 119 ft. over fantails, 100 ft. from bow to transom, 28 ft. beam, 5 ft. deep. The engines are- of the usual western river type supplied with steam from two. cylindrical boilers of the two flue type, 24 ft. long. George W. Smith has been ap= pointed agent of the Anchor Line at Minneapolis, Minn., in place of C. A. Clawson, deceased. 4 a d : 4 s