20 



NATURE 



[November 2, 1899 



Sir John Murray and Mr. Robert Irvine discussed the dis- 

 tribution of albuminoid matter and saline ammonia in sea- 

 water ; and Sir John Murray with Mr. F. P. Pullar exhibited 

 and described the sounding-machine they employed in their 

 bathymetrical survey of the fresh-water lakes of Scotland, and 

 gave an account of the configuration of the beds of the lakes of 

 the Loch Katrine group. The authors expressed their inten- 

 tion of extending the work to the other lakes in Scotland, 

 although they felt that it was rather for the nation than for 

 individuals to carry out work of the kind. 



Other Papers. 



Colonel Sir John Farquharson, late Director General of the 

 Ordnance Survey, gave an account of the progress of the work of 

 that department during the last twelve years, and exhibited a 

 nurnber of illustrative diagrams and specimen maps. He said that 

 during the twelve years ( 1 887 -99) there have been probably more 

 changes made in the character of the work done by the Survey 

 than in any other equal period of its history ; and, as regards 

 the areas covered by its operations, they have been largely in 

 excess of the areas covered during any previous equal period. 

 This is, of course, due to the fact that revisions have now 

 largely taken the place of original surveys. The most important 

 advances made were : — 



The progress (to completion in 1890) of the original cadastral 

 survey of England and Wales, including the 6-inch surveys 

 of uncultivated districts. The progress made on re-surveys 

 for the larger scales of various counties of England and Scot- 

 land which had been originally surveyed for the 1 6-inch scale 

 only ; and the progress made on the revision of the original 

 -cadastral surveys of England and Scotland, whether on the 

 25-inch or 6-inch scale. The progress made on the re-survey 

 of Ireland for the ^J^^ or 25 -inch scale. The progress made 

 on the completion of the original new series engraved i-inch 

 maps of Great Britain and Ireland, both in outline and with 

 hills. The progress made on the revision of the new series 

 of I -inch engraved outline maps of Great Britain and Ireland, 

 and the commencement of the issue for Scotland and the North 

 of England (and for Ireland ultimately) of the same revised 

 I -inch map with hills in brown by double printing. The 

 progress made with coloured i-inch maps of the South of 

 England. The progress made with maps on scales smaller than 

 I inch to a mile. 



A short account was given of the nature, causes, and results 

 of the changes made since 1887 in the system of carrying out 

 the survey, some of which were due to the reports of com- 

 mittees, or suggestions from the general public, while others 

 ■have been necessitated by the changes which have taken place in 

 •the character of the work done by the Department. 



The Ordnance Survey Department, in 1887, published town 

 maps at the cost of the State, on the scales of 10 feet {-^\^) and 

 5 feet (ic^^^^) to a mile. It does so no longer. The reason for 

 this change was stated. The sales of the Ordnance Survey 

 maps were in 1887 in the hands of the Stationery Office ; 

 they are now in the hands of the Ordnance Survey Department 

 itself The reasons for and results of this change were stated. 



Some remarks were also made as to the organisation and 

 ■superintendence of the department and of its work ; as to the 

 use made of the Ordnance Survey maps by other departments of 

 the State and by the public generally ; and as to the important 

 work which still remains to be done by the Ordnance Survey. 



Mr. Vaughan Cornish described the sand-dunes bordering the 

 delta of the Nile dealing with the ripples, sand-dunes, and dune- 

 tracts in turn. 



Ripples. — The author had previously measured twelve wind- 

 formed ripples in the blown sea sand on the Dorset coast. The 

 average ratio of length to height was L/H = 18-4. The least 

 height was '06 inch, and the greatest -34 inch. These measure- 

 ments were, for the most part, of one or two individual ripples. 

 Mr. E. A. Floyer measured six of the largest kind of ripples on 

 the El Arish route, and obtained L/H = 177 with H from 6 to 

 IO-6 inches. The author measured thirty-seven consecutive 

 ripples to leeward of a sand-dune near Ismailia. The ripples 

 had an average height of i -43 inches, and the average L/H was 

 i6"57. The appearance of these was intermediate between that 

 of ripples where accumulation is rapid (which never grow large), 

 and the large and nearly symmetrical ripples (? analogous to 

 sastrugi), as much as li feet in wave-length, the formation of 

 which is apparently accompanied by a considerable lowering of 

 the general level. 



NO. 1566, VOL. 61] 



Dunes. — A tract of a few hundred acres of small, but true, 

 dunes (not ripples) on a sandy foreland, exposed during the fall 

 of the Nile, afforded an opportunity for similar measurements. 



Higher and lower dunes succeeded one another, and, viewed 

 transversely, the ridges were strongly undulating. Nevertheless, 

 a line having been marked out in the up-and-down-wind 

 direction, the average L/H for twenty-four consecutive dunes 

 was found to be 1 8 -04, average height 20 inches. Another set 

 of measurements taken near the same line on the succeeding 

 day gave L/H = 17*89 for twenty-three consecutive dunes. 

 Apparently the ridges are formed of the nearly uniform (L/H 

 = 18) shape, and lateral inequalities are subsequently developed 

 in the manner explained in the Geographical Journal, June 1898, 

 pp. 637-9, but these do not affect the average L/H. The author 

 hopes to make similar measurements of trains of larger dunes. 



The straight, slipping lee cliff of dunes is caused by the under- 

 cutting of the eddy. In the dunes near Ismailia a progressive 

 development of the profile form was observed. At first both 

 windward and lee slopes are very gentle, and the highest point 

 is near the middle. The summit apparently moves to leeward, 

 and the lee slope becomes steeper ; a slipping cliff is formed on 

 the upper part of the lee slope. This pushes back towards the 

 summit, and the windward slope grows steeper. Finally, wind- 

 ward and average leeward slope become of nearly equal steep- 

 ness, and the top of the cliff coincides with the summit of the 

 dune. 



Dune Tracts. — The condition for formation of a dune tract 

 in a sandy district is that the rate of travel of the sand should be 

 locally diminished without a corresponding diminution in the 

 supply of sand. The persistence of such a condition may cause 

 a stationary dune massif without fixation. 



In the sandy district visited by the author the formation of a 

 dune tract or dune massif appears to be chiefly determined by 

 the presence of ground moisture, which gives coherence to the 

 sand. Thus the boundaries of these massifs frequently appear 

 inexplicable when an explanation is sought in the wind. Within 

 the bounds of the massif, however, the modelling of the surface 

 is explicable by the action of the winds. In the neighbourhood 

 of Helwan, wind erosion of limestone and other rocks is very 

 active over areas where there are no dunes. An examination of 

 the wind-formed detritus showed a quantity of sand-sized par- 

 ticles sufficient for the formation of dunes ; and the explanation 

 of their non-formation seems to be that the sand-sized particles 

 are too small a proportion of the whole. According to this line 

 of reasoning, dunes will only be formed where dust formation 

 proceeds slowly, for if dust be produced rapidly the proportion 

 of sand-sized particles remains low. 



Travel papers, for the most part accompanied by graphic 

 illustrations, were contributed by Mrs. W. R. Rickmers on the 

 rarely visited region of Eastern Bokhara, by Mr. W. R. 

 Rickmers on the Karch-Chal mountains in Transcaucasia, by 

 Dr. H. O. Forbes on the island of Sokotra, by Mr. O. H. 

 Howarth on the province of Oaxaca in Mexico, by Dr. A. 

 C. Haddon on some geographical results of the recent 

 Cambridge anthropological expedition to the Malay Archi- 

 pelago and New Guinea, and by Captain Wellby on a remark- 

 able journey through the western borderlands of Abyssinia. 

 Mr. E. Heawood contributed a paper on the date of the 

 discovery of Australia, in which he brought forward evidence for 

 discrediting the rumours of the discovering of Australia in the 

 fifteenth century or the early part of the sixteenth. 



The eighth report of the Committee on the Climatology of 

 Tropical Africa was presented, giving records from forty 

 stations. 



MECHANICS A T THE BRITISH ASSOCIA TION. 



lyrEETING under the presidency of Sir William White, 

 ■'■■*■ Chief Constructor of the Navy, naturally the papers 

 which came before the Section dealt mainly with marine 

 engineering, canal and harbour works, and allied subjects. 



Owing to the energy of the President a very complete 

 programme was secured ; and the papers read and discussed 

 were certainly considerably above the average. The attendance 

 at the sectional meetings was also much better than usual. 



On the opening day, after the presidential address, a paper by 

 Messrs. Coode and Matthews on the Admiralty harbour works 

 at Dover was submitted to the Section. It was taken early in 

 the programme in order that the engineers present at the 

 meeting who naturally wished to carefully inspect the 



