KiNAHAN — Beaufort'' 8 Dyke, Coast of the Mull of Galloxoay. 31 



continuously long enough to carry tlie sands, etc., to the south end of 

 the gulch ; they therefore were stopped or even driven backvs^ard by the 

 ebb tide current, thus forming an accumulation between the southern 

 deep and the deeps in the other portion of the gulch. 



All these suggestions are necessarily extremely speculative, as the 

 charts are valueless for reliable conclusions, as we do not know under 

 what conditions the soundings were made — the winds and state of the 

 tide being most important consideration, — a continuous wind, either 

 from the northward or southward, during the survey, would materially 

 affect its correctness. To form correct conclusions from any of the 

 charts, it would be necessary to have also a concise record of the 

 conditions that existed during the time occupied in the Survey. 



JS'OTES ADDED IN PRESS. 



The rule of the Admiralty is : all charts should be corrected up 

 to the date of last survey, and all prior charts should be cancelled 

 and withdrawn from sale. I have an old copy of the chart of the 

 British Isles, 1867, but no copies can now be bought of the charts of 

 1879, 1885, 1890, and 1894. I sent a copy of No. 45 (date of last 

 survey, July, 1897) ; since then there have been most elaborate surveys 

 — in December, 1897; in May, 1898; in July, 1898; in September, 

 1898; and, in November, 1898, — the result of these latter surveys 

 being Sheet I., Irish Channel — previously Sheet 1 825 a. The principal 

 re-surveys were in August, 1872, and July, 1888. 



A remarkable difference between chart 45 (1897), and Sheet I., 

 Irish Channel, is: on the first, the "Race," at the Bill of the Mull, 

 is made to run west and north-west ; while, on the latter, it is recorded 

 as running into Luce Bay. 



"What are drifting sands, off the coast of Wexford, Wicklow, and 

 Dublin, composed of ? Blocks, sometimes of large dimensions (see 

 previous Papers, accounting for how they came there) : gravel (coarse 

 sand), shells (shell-sand), mud (fine sand), ooze (typical mud) — all 

 things that are adjuncts of drifting sands, except the large blocks, will 

 be found in the "Beaufort's Dyke," on chart No. I., of the Irish 

 Channel. 



