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April, 1909 probably use it, to say nothing of navi- gating Third, advocates of the sea One of level type ina as. to. Currents. the letter to Engineering News gravely states that the tidal currents set up in the canal and reaching about 3 miles per hour, calculated on the entire area of cross section of canal, would be no He instances of navigation in much higher hindrance to navigation. quotes currents, such as the fower Mississippi in flood, the North River at New York and some tropical streams navigated by flat bottomed light draught boats. It is almost a waste of space to point out that maneuvering or. steering a ship in a current is almost entirely a ques- tion of the relative volumes of the ship and the stream. <A _ ship which could be full up North River in any current driven. and steered at speed could not be driven one foot at full speed (as actually suggested) in a canal or narrow stream. ter a ship of say 60 ft. beam and 28 it. draught could not be driven one hun- dred yards in the proposed sea level canal at full speed, even with no cur- rent whatever. And as a ship can only be steered as she has motion relative to the surrounding water, a vessel trav- mile current would actual speed of veling with a 3 necessarily have an something over that in order to have . steerage way, say an additional 3 miles. The control of such a ship in a sea level canal under such conditions, to say no- thing of meeting other ships, in a channel only 150 ft. wide and at whicl: point the current is consequently greatly accelerated, is something which only a devoid of knowledge would consider without a shiver. The author of the letter referred to quotes man practical the Detroit River as an instance of navigating in a 4-mile current. There is no point in the Detroit River where such a current exists, but even admit- ting that it does it has no bearing on the case whatever. The Detroit River is wide, and except for a short dis- tance at the lower end, relatively deep, so that speed is affected very little and except at one point, steering not at all, _and this point is always navigated at slow speed. : none of any consequence in for that mat--- TAE Marine REVIEW The time occupied in lockages is more than made up by the greater fa- cility of navigation in the lock canal but this time is not nearly so great as to. be The average lockage at the Poe lock at the Soo is seems supposed. about 40 minutes, and although the locks at Panama are slightly larger than the Poe, the arrangements for filling and emptying will doubtless be in proportion, and probably better, so that the three should lockages con- not sume over three hours at most. It should be remembered too, that the larger the ship the smaller the volume of water to be handled and the The to also speaks of the to locks at shorter the time lost in lockages. author referred experience with the: Soo, accidents while as a matter the en- tire 54 years, as we have had occasion to note in a previous issue. We ques- lion ai 4 navigator can ve found who, when he fully understands both plans, will not unhesitatingly declare for the lock type, even though ine may never have done any locking, while to those who have the problem has no terrors. It has been gravely argued that the locks or gates might be damaged by a ship being driven into them at high speed. Any one who has ever seen a large ship moved into a lock chamber must know that the only way to get her in at 'all is to shift her slowly and the larger she is the greater the difficulty-- because the ship so nearly fills the gate that the impounded water which must be displaced by the ship can only find exit slowly through the contracted area past her sides and bottom. To a lesser extent the same condition exists in the sea level type of canal and any effort to obtain speed must not only result in failure but probably in disaster. The same argument holds true of course even in the much greater section of the lock-type but to a greatly lessened ex- fen A GRAND DUKE TACKLES THE PROPELLER, For a thing that has been improved and reformed so much and so often, the screw propeller is the most con- firmed back-slider in the universe. The of fact there have been a7 names of those who have become en- thusiastic in the cause at some time or other is legion, and from Greenland's - icy mountains to India's coral strand the hosts come to take a hand in the great uplift. The march of improve- ment exemplifies the definition of two parallel lines as those which constantly approach each other and never meet. Once more we are informed, and by The Marine Engineer, London, that the screw propeller is given another long lift on the way to perfection, and this time by no less a person, or as we suppose we should say, personage, than His Royal Highness the Grand Duke of Oldenburg. ' Strange to say, H. Roo. has not de. cided that the vulgar type of propeller, so far as the shape and number of blades is concerned, is all wrong, where- in he differs from most of those great inventors whose deeds live after them and -whose improvements in screw pro- pellers have produced large revenues to the patent office and added to those on the waiting list, but he has discov-. ered that the proper fore and aft position of the blades on the hub is the key to the whole miserable business. Instead of all plane they lie in' different planes, so the blades lying in the same that a four-bladed propeller for in- stance, can lie four times as often as the common type. This excessive men- dacity is only apparent, however, and not real, since H. R. H. assures us that by stepping the successive blades backward in relation to each other the ship is made to step forward, as it were, with great celerity. Of course, slip is lessened; we re- gret that we are obliged to admit that H. R. H's excessive modesty does not permit him to claim outright that he -- has abolished it entirely, and the im- provement in those instances where the new type has been applied is in no case less than 9 per cent, running up to 33 per cent. We may say here that in this respect the new propeller is right up to the mark, as all improved propellers are supposed to show some such range, otherwise it is at once ap- parent, that they. would not be improvements. The step- ing of the blades does this "by pre- even to a layman,