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THE Marine REVIEW eo : : WY ing are rectified, vessels have become oblivious of the means for correcting position in thick weather and of ascertaining set and drift of current independently of the methods used in clear weather. Negligence in this respect has gone so far that, in fact, no facilities for determining the corrections for current are found aboard of any vessel, and the lack of such facilities is, in a large measure, the cause of errors in courses and distances. To remedy this evil it has been suggested that vessels be equipped with the "ground log." The ground log consists of a heavy weight attached to a line divided into a forerunner of from 50 to 80 fathoms, and a sufficient number of knots of 25 ft. length. After the weight is lowered to the bottom and the forerunner is out, the counting commences, and the knots running out in 15 seconds give the rate of speed that the vessel is actually making over the ground in nautical miles per hour, which requires a small tabular correction for depth of water. The direction of the ground log line indi- cates the ship's course over the ground, and the angle which the line makes with the ship's keel, applied to the correct magnetic course the vessel is heading on, furnishes the true course made good. While the ground log is correct in prin- ciple and is not influenced by currents, it cannot be relied upon at all times and under all circumstances. It is evident that, to get the correct direction of the current, the ship must make a mathemetically straight wake during the operation, and her speed must be slow. In stormy weather the ground log could not be used to advantage, on account of the "send of the sea" and drift to leeward; hence, the whole operation would be little better than a good guess. The lead plays the prominent part in coasting and the verifying of position in thick weather, but its judicious use is very little known, From time immemorial the lead has been justly looked upon as one of the mainstays of navigation, but it is not the indiscriminate casting. of the lead on any course run, the practice in general use, which insures safety and prevents deception, but the shaping of courses and taking _ of soundings with regard to leading features of the ground, easily picked up and followed by compass and lead. The bottom of the lake is most conveniently represented in charts, or should be represented, (the. Hydrographic office charts are) by curves at different distances from the surface of the water, which curves are to be used in thick weather as general safeguards against stranding. They are guides, just as much as other aids to navigation, if known how to be used, and by their means the ship's place is found in thick weather. A continuous curve of equal depth, including all dangers to navigation along a certain part of the coast, and passing the danger nearest to the curve at a safe dis- tance, is called a safety curve. For, by keeping the vessel in no less water than the depth of the safety curves indicates, stranding is prevented. Thus, the safety curve is a sure in- dicator of the boundary up to which a vessel may safely proceed. Furthermore, the safety curve, or any other curve of greater depth, may be used as a guide, especially in thick weather, and it is the straight parts of such curves which furnish reliable lines of position under all circumstances. Such a line followed up by compass and lead and continued over its tangent point will cut some other curve of different depth, the point of intersection invariably furnishing the true place the ship is in. The study of problems of this description, on the correct solution of which. frequently the safety of a_vessel in thick weather depends, is thoroughly neglected. t of the lead is worse than useless, inasmuch As a single cas : n of the ship, as it may canfirm an error in the assumed positio the necessity for repeated soundings must be apparent, and these repeated soundings must be made without stopping the ship or deviating from the course. This 1s only supplied by the patent sounding machine, many varieties of which are now on the market. Over long routes out of sight of land, or in thick weather, the navigational sounding apparatus, for use with pianoforte wire, would be invaluable for determining positions, or at least for indicating the set and drift of the vessel. With this apparatus, Atlantic liners get soundings in -- depths as great as 100 fathoms (600 feet) without stopping the engines. The apparatus, briefly described, consists of a drum, about a foot in diameter and four inches wide, upon which 300 fathoms of steel pianoforte wire are tightly wound. To the wire is attached nine feet of log-line, and to this is fastened an iron sinker, about twice the length of the or- dinary lead, but not so thick. On the log line, between the wire and the sinker, a small copper tube is securely seized. The lower end of this tube is perforated; the upper end being opened or shut at pleasure by means of a close-fitting clap. When ready for sounding, the copper tube contains a smaller sized glass one. This latter is also opened at the bottom end, and hermetically sealed at the other. The drum is fitted with a brake, which, on a cast being taken, controls its speed, and ultimately arrests it when the lead touches the bottom. A pair of small winch handles winds up the wire again, and the depth is shown by the height of the discoloration on the insidé of the glass tube. : (To be continued.) LIVERPOOL SHIPPING LETTER. Liverpool, May 7.--The casualties to vessels of 500 tons gross register and upwards which have been posted in the Liverpool Underwriters' Association loss book during the month of April, include the following total loss: British sail 3, tonnage 5,950; British steam 3, tonnage 7,692; for- eign sail 4, tonnage 4,270; foreign steam 6, tonnage 12,185. The totals of these figures were 16. vessels and 30,097 tons, as against 14 vessels and 19,056 tons for the corresponding month of last year. During the month the aggregate partial and total losses were 345, as against 362 for the corresponding month of 1905, 327 for April, 1904, and 380 for April, 1903. The nature of casuality is returned as follows: Collisions, 118; strandings, 107; damage to machinery, shafts and propellers, 46; fires and explosions, 22; founderings and abandonments, 3; missing, 1; weather damage, 38, and other casualties, 10. The gross tonnage of the ships which passed through the Suez canal in the first quarter of the year was 4,934,345 tons, against 5,130,424 tons in 1905, and 4,648,529 tons in 1904. The net tonnage in the three years respectively was 3,527,243; 3,701,148; and 3,306,539; the number of small craft was 298 in 1906, 674 in 1905, and 8o1 in 1904, their tonnage in the three years being 5,287, 8,227, and 9,936 respectively. The tonnage dues received were 27,160,623 f. in 1906, 30,923,219 f. in 1905, and 28,055,546 f. in 1904. The passenger receipts in the three years amounted to 979,290 f. 668,083 f. and 70,012 f., respectively. The fact that the order placed by the Allan line for a new steamer of over 10,000 tons, to be fitted with reciprocating engines, and not turbines, has occasioned much comment in British shipping circles during the past week. Everyone seems to have jumped to the conclusion that Messrs. Allan Bros. & Co. are not satisfied with the performances of their turbine steamers, Victorian and Virginian, but this assump- tion' is quite unjustifiable and the Allan line are most anxious that this should be widely known. The new ship ordered, it appears, is intended to take the place of the Bavarian, whose services were lost to the company last year by strand- ing in the River St. Lawrence. The new boat is only meant to steam 16 knots, and it would be an obviously mis- taken policy to equip such a vessel with turbines whose chief value lies in their adoption in passenger liners to run at high sea speeds. The company, it is important to add, express the utmost satisfaction with the Virginian and the