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1903.] MARINE REVIEW AND MARINE RECORD, Gannet Rock Lighthouse, Bay of Fundy. tidal station at St. Paul's island is taken for reference rather ~ than' Pictou -in- the' strait itself. = eee "On the Pacific coast good progress has beén made, both in the improvement of the tide tables through an analysis of further tidal records from the principal stations and also in the estab- lishment of additional tidal stations to extend the information available. The stations for which the tide tables are primarily calculated are Victoria' and» Sand Heads in the Strait of Georgia and the results deduced from these are much better than can be obtained from comparisons with Port Townsend, as given in the tide tables of the United States coast survey. The reason for this is the difference in the character of type of the tide. Five summer tidal stations were erected this sea- LC son with the object of obtaining tidal . data as a basis for the investigation . of the currents at the entrance to the . Bay of Fundy and also in the bays of the south coast of Newfound-. land." ee : Concerning aids to navigation in general Lieut. Col. Anderson says: "We meet with a good deal of dif- ficulty and disappointment in oper- ating our fog signals. This is be- cause we cannot make mariners un- derstand that sound signals are ex- tremely liable to aerial disturbance Theoretically, sound waves are prop- agated in straight lines in all direc- tions from their source, exactly as light waves are propagated. Prac- tically these straight lines of sound waves are deflected by any little ir- regularity in the air through which. they pass. If the air is not wholly homogeneous the 'sound waves will not pass through it in straight lines but will be. deflected, and whether the deflection is down towards the surface of the water or up into the air the effect is the same; the sound does not travel parallel to the surfece of the sea and is lost to the sailor who is listening for it. A small island, a reed, or rocks, or even a shoal lying outside of a fog alarm station will have the effect of un- equally heating the air which covers them, and the air thts separated into strata ee causes refraction of the waves of sound, and the fog ala comes ineffective. The same thing may happen, ee Seas so likely to do so, where poe of . natural obstr apparent. 'Times without number compial : ioati oie of our fog alarms was not in operation, He eens proved that it was sounding as loudly as ever, the as caaek with atmospheric conditions. For these io ie a fog sig- ners that they must never judge their distance i of unequal densities, aint has been made that_ 27 nal, either by the power of the sound or by the absence of sound, because under certain conditions of atmos- phere the sound may be heard loudly at long distances from the alarm; under other conditions it may be lost at a very short distance, and these conditions may vary at the same sta- tion within very short intervals of time or of space. Unfortunately it seems impossible to convince cap- tains of this, and many wrecks have _ftesulted from their ignorance of these well-known aberations. "Danger signals that have been greatly improved in later years are floating aids to navigation, including lightships and buoys. The modern lightship is a reservoir of compli- cated machinery, containing appar- atus for revolving lights at the mast- head; powerful fog signal machin- ery; auxiliary power for propelling the vessel in case she breaks away from her moorings or is obliged to run for shelter, and mechanical ap- pliances for relieving the strain on the anchor in heavy weather. <A lightship, however, can in no way be considered as satisfactory an aid to navigation as a solidly-founded light- house because the motion of the waves prevents the light from being .seen at a great distance, and in our climate a vessel must leave her sta- tion when ice forms, and is, there- fore, unavailable at the time naviga- tion is closing, when an aid is most urgently required; moreover she is liable at any time to break from her moorings, and may therefore not be found at the place expected. The one point in favor of a lightship is that her station may be so located that vessels can run much closer to her than they can to a light on the land. "In 1899 there was an international convention on the sub- ject of buoyage, which resulted in the adoption of rules to gov- ern the shapes and colors of buoys. Canada has adopted these international regulations, and all our larger buoys have been' made to conform in shape as well as in color to these interna- tional regulations. To make the necessary improvements in- volved the furnishing of a large number of conical buoys. The Belle Isle High Lighthouse. i ity that has been shown in the development of signal paove te: most interesting. The earliest signal buoy is the . bell buoy. I doubt if-it has been much improved since the eighteenth century. The Courtenay whistling buoy is a -- successful, ingenious and original invention. It is fitted with a long cylinder reaching down into the sea below the wave action. As the buoy rises and falls on the water this cylinder acts _ air compressor, the compressed air being forced out through a large whistle on the superstructure, and emitting a fitful and dis-