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THE MARINE RECORD. 7 SSeS Seseensneesessecnnscssssssssssesessessee se eee compass course may be represented by a straight line on a Mercator’s chart, is common to the whole world of navigators. This peculiarity lies in the rapid change of variation for change or difference of longitude.. ‘There is but one other district or area of navigation on the face of the earth similarly conditioned, and that is the north- ern part of our Atlantic Coast, say from New York to Newfoundland, where the feature is almost precisely the same as with us. ~ There are indeed two other areas where this condi- tion prevails, but, as there is only asmall amount of “commerce on them, the results are not so much noticed. These areas are Hudson Bay and Bering Straits. The method of applying the ‘‘mean variation” in shaping course on the lakes, is effected, but, in the case _ of long runs it is objectionable in that it leads the ship considerably off the right line between the points of de- parture and of destination, thus exposing her to dan- ___ gers not seen at first. _.To obviate this difficulty I have suggested a swing of the ship’s head, at frequent intervals, counter to that of the card, thus involving a frequent change of course. From Whitefish Point to Duluth, a distance of some 287 nautical miles, the cards swing about 9°, or say 1° _ for every 32 miles of eastings or westings. (See Fig. 3.) Then, suppose that after sailing 15 or 17 miles on our ‘course, we swing ship’s head to south 1°. Then after sailing 30 to 35 miles further, as indicated by our log, accordingly as we are on an 8-point course, or on an oblique course, we swing ship’s head again 1° south, and so on to the end of our voyage or run. By this means we would keep close to the right line joining the two points between which we set out to sail, and never more than ye? off our course. Andinthis case we would apply only the variation at the point of departure. For the lower lakes, about 35 miles for 1° would be the proper dis- tance. H.C. PEARSONS. Ferrysburg, Mich. March 28, 1896. [Captain Pearsons’ let- ter contains a number of valuable observations, but we would hardly advise any one to read it in the hope of gathering new in- ’ formation, as it is mislead- ing in some respects. Capt. Pearson writes of conver gence and inclination of meridians in connection with the Mercator chart. On calculations on this chart. The idea of securing the meau variation is by no means new, but is recom- mended by the Hydrographic Office for short distance Sailing. No Hydrographic Office charts that we have ever seen contain any instructions on this line, and the only occasion in which the variation of the point of de- parture alone is allowed for in shaping a course is in long distance sailing, where applying the mean varia- tion for the whole. distance would cause the ship to traverse an unnecessarily greater distance. On long distance sailing, on salt water, the ship’s position is taken as often as every four hours and the ship’s course is shaped anew as often, if thought necessary. Capt. Pearson offers this, apparently, as a discovery of his own. We hope to print a communication next week which will correct..the errors_contained in the above communication, which contains much that is of value. —Ep ] is LAKE SUPERIOR BEING DRAINED? To the Editor of The Marine Record: In all the discussions I have noticed in the papers relative to the low water on the lakes,-I have failed to notice that any attention has been called tothe raise of water on Lake Superior. In the last four years the water in this lake has raised about two feet. In ’92 it raised about 8 inches. In ’93 about 7 inches, and in ’94 about 9inches. In ’95 it about held the same level as in 04. These figures in regard to the rise of water are ap- proximate, as my informants and personal obligations - did not require the keeping of the exact record. In looking for the reason of this rise, particularly when the lakes whose level is below Superior have been A METAL DUCKING BOAT. this chart the scale gradually lowering in the abovetime, [have come to the is prepared so as to make the meridians strictly parallel conclusion that on account of the dredging that is being and this does away with convergence or ae | in Nore.—In Fig. 3 the curvature of the short parts of the ship’ s track is graced exaggerated, in order to avoid confusion of lines. H. €. P. done at the head of the American and Canadian ‘‘Soo”’ canals, and the dumping of the same at the ‘head of the rapids, the head of the - “Soo’’ River is being gradually dammed, thus keeping the level of Lake Superior . manyfeet higher than it should be above the lakes below. _It would probably be well for those most interested tolook this matter up and see if this is nota solution for a part of the low water whose level is below Superior. SUBSCRIBER. Sand Beach, Mich., March 28. Probably the first fuel sold toany large boat on Detroit river this season was sold to the steamer City of Detroit last Saturday at Graham’s rapid fueling docks, atthe foot of Twenty-first street. Mr. Graham, who entered agressively into the vessel fueling business last year, is a pusher and has a location which is m uchin his favor in securing a good share of the trade. The Johnson Co., of Lorain, have an- nounced that they expect to handle 1,500,- 000 tons of freight of all kinds at their dock in Lorain this season. BOATS FOR HUNTING AND FISHING. Mr. W. H. Mullins, of Salem, O., whose advertisement appears on another page, has the following to say about his boats, especially those adapted to duck hunting, one of which is shown in the accompanying illustration: Realizing from my own experience asa duck hunter the need of a practical, seaworthy, staunch and durable boat, I have, at considerable expense, modeled.and made dies for making the safety duck boats which I am offer- ing to the trade, and to the duck hunters of the country. Iam making my boats in four materials, soas to meet the requirements of the different shooters. My alumi- num boat is the nobbiest, lightest, and most artistic boat that has ever been brought ont, and for those who can afford the luxury of a boat made of this materia], is undoubtedly the xe plus ultra, My Manganese bronze boats will be found practically indestructible, and a most perfect sporting boat. For the manufacture of these boats Iuse Manganese bronze, the same as re- ‘cently used for the sheathing of the American yacht De- fender. It is stiff, tough, and very durable, aud un- doubtedly the best material for the manufacture of boats ever introduced. Manganese boats and copper boats will probably be found preferable to aluminum for use in salt water or marshes bordering on the sea. My galvanized steel duck boats are made of the very best quality of this metal, and where a low cost boat is wanted, are preferable to anything that has ever been devised. They can be finished at a cost to compare with the cheapest wooden boat placed on the market, and there is no comparison between the wearing qualities of the two types. The steel boat can be left exposed to the weather for months ata time, and will be as tight and seaworthy at the end as if not exposed, whilea wooden boat would crack open and be rendered use- less. “All my different styles of duck boats are stamped in dies by very heavy and powerful machinery. The construction is simple, rigid, water-tight, and se- cure. The boat is ex- tremely light in weight aud durable. At either end of my boatsI use a large air chamber sufficient in size to float four men on the upturned boat should it happen to capsize, ren- dering it practically non- tinkable. The bracing of he boats is secured by head-shaped ribs of 20- guage steel, copper or aluminum, as the case may be, riveted at equal distances on the inside of the boat, making the lightest and strongest possible construction. The bottom is moulded after the lines of the McDougall whaleback vessels, the shane being such as to enable the hunter to run into very shallow water, through ta .- gled grass and reeds, and over light ice and hidden logs and obstructions with the least possible labor and dan- ger. With this boat is furnished a light reversible wooden bottom or footboard, a moveable seat, a pair of oars, pushing oar and paddle.”’ Mr. Mullins also manufactures a fine double-ender pleasure boat, with air chambers, and a square-stern pleasure or fishing boat. On special contracts Mr. Mullins fits his boats with folding centerboard and rudder, and arranges a mast support, with any other practicable changes or addi- tions. EEE Oe A GOOD RECOMMENDATION. The following has been received by a prominent local company which has been making inquiries in regard to the merits of the Empire Boiler Cleaning Compound: Replying to your favor of the 19th would say that we have been using the Empire Boiler Cleaning Com- pound in the boiler of steamer Richard Peck for over a year, and can positively assert that it is the best boiler compound we have ever used. It hasthoroughly cleaned our boilers and has stopped all incrustation. In fact it has accomplished all that has been claimed for it, and we are entirely satisfied. Yours truly, FRANK Soup, Supt. Eng. New Haven Steamboat Co,