SCIENCE 



FRIDAY, AUGUST 17, i888. 



The Pilot Chart of the North Atlantic Ocean for August, is- 

 sued by the Hydrographic Office under direction of Commodore 

 John G. Wall<er, chief of Bureau of Navigation, is accompanied by 

 a supplement containing a large amount of useful and interesting 

 information concerning derelicts and wreckage on the high seas, 

 with a graphic and complete record of the tracks followed by some 

 of the most notable derelicts reported on back numbers of the chart. 

 Most noticeable of all, and of especial interest at the present time, 

 is the complete history, up to date, of the great log raft abandoned 

 off Nantucket last December, with a tabular statement of every 

 report received from masters of vessels since that time, of logs 



the tracks which the scattered logs from this great raft have fol- 

 lowed, drifting, as they do, under the combined and varying influ- 

 ence of wind, tide, and current, and every log offering some slight 

 difference of resistance to each, according to its size, weight, and 

 depth of flotation. To the practical navigator, however, it will be 

 of still greater interest to have logs shipped in the usual way, or at 

 least more securely tlian was done in this case, in order that dan- 

 gerous obstructions may not be added in this wholesale manner to 

 those which, in the ordinary course of things, he has to guard 

 against." The tracks of derelict vessels are also of great interest, 

 and clearly illustrate how long these dangerous obstructions often 

 remain afloat. For instance, one of them drifted 2,800 miles, and 

 another the enormous distance of 3.500 miles (from off the capes of 

 Chesapeake Bay to the Bay of Biscay, by a circuitous route). 



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from the great raft. This table contains 134 reports, and although 

 a few of them relate to timber from vessels' deck loads, yet the 

 great majority are undoubtedly reports of fragments of the log raft. 

 The graphic representation of the manner in which these obstruc- 

 tions to navigation have spread over the Atlantic is very impressive : 

 their general drift was at first about south-east, under the influence 

 of the prevailing north-westerly winds, and then almost due east in 

 the Gulf Stream, the plotted tracks reaching well over to the Azores, 

 where, indeed, one of the logs was towed into port on June 14, ac- 

 cording to the United States consul at Fayal. Some of them are 

 now to the northward of the Azores, drifting north-easterly, and 

 others to the southward, drifting south-easterly, and of the former 

 some may yet reach the shores of Europe. A considerable amount 

 of driftwood was observed farther north, but, from the descriptions, it 

 appears that it did not belong to the raft. That portion of the map 

 referring to the gradual dispersion of this mass of timber has been 

 reproduced above. 



The almost world-wide notoriety achieved by this great log raft 

 lends emphasis to the following remarks, quoted from the chart 

 itself : " To the student of ocean currents, it is interesting to watch 



The I-lydrographic Office, of which Lieut. G. L. Dyer, U.S.N., is 

 now in charge, is enabled to collect and publish data of this kind 

 in complete and reliable form by means of the facilities of the 

 branch hydrographic offices established in our principal seaports, 

 the establishment of which has been of the greatest assistance to 

 our mercantile marine, and has greatly strengthened the navy in 

 their estimation. The Pilot Chart itself for August shows a new 

 feature, which will make it of still greater value. It contains the 

 tracks of all the notable August hurricanes on record, thus indicat- 

 ing at a glance both the regions where they are liable to be en- 

 countered and the general direction of the paths which they follow. 

 A descriptive article on the chart calls attention to the fact that 

 August is the great hurricane month, and describes the tracks fol- 

 lowed by the two memorable hurricanes of August of last year, one 

 of which is perhaps the most notable on record, beginning near the 

 Cape Verde Islands, off the coast of Africa, and thence traversing 

 the entire ocean to the westward, curving to the northward past 

 Cape Hatteras, and thence about east-north-east across the Grand 

 Banks, and re-crossing the Atlantic towards the British Isles and 

 northern Norway. In this way the good work of the oflfice is 

 kept up. 



