1884.] 



MICROSCOPICAL JOURNAL. 



155 



no, the result is the same as in the 

 previous cases, but these last exam- 

 ples all declare in the flint particles 

 present, flakes unrounded in opposi- 

 tion to the rounded quartz, that the 

 last is ancient, produced by the attri- 

 tion, perhaps of ages, whilst the other 

 is modern and recent. This evidence 

 is remarkable, as it declares an im^ 

 portant fact in our inquiry, which 

 points to the one as ephemeral, to the 

 other as of an unknown duration, 

 perhaps dating its origin from the 

 primitive rocks. 



From Dymchurch, in Romney 

 Marsh, w^here the flint shingle is seen 

 extending for miles up to the point 

 of Dungeness, and always increas- 

 ing, the sands reveal the same oft-re- 

 peated tale — quartz, w^ith an almost 

 entire absence of flint particles. 



I do not here pretend to show 

 whence proceeds this abundant sup- 

 ply of quartzose sand all around our 

 coasts. It is a matter for further in- 

 quiry and investigation, but one must 

 suggest the probability of it being, in 

 pait at least, brought down by rivers. 

 And this will at once lead us to con- 

 sider whether that noble sti-eam, the 

 Rhine, may not be one of the factors 

 of supply. Descending from the Alps 

 in a strong and powerful current, gen- 

 erally turbid, but particularly so after 

 a season of storms on the breaking up 

 of winter, it has for ages poured forth 

 its waters into the German Ocean. I 

 know nothing more imposing than 

 the scene presented, when looking 

 down from the hills beyond Bonn 

 upon the vast delta before you. It is 

 as level as the sea, and far on the ho- 

 rizon the city of Cologne is detected 

 only by the lofty towers of its cathe- 

 dral, as if a ship riding on the ocean. 

 Its many mouths must each send forth, 

 mixed with its strong current — for it 

 is not tidal — a mass of sand, repre- 

 sented doubtless by the dunes of Hol- 

 land and Belgium, which have been 

 planted with Equisetum to tie to- 

 gether its instable substance. The 

 Alpine loess of Belgium is itself large- 

 ly commingled with quartzose sand of 



similar origin, making a large source 

 of supply. 



Amongst other materials than 

 quartz referred to, chalcedony is the 

 most common ; there is also a kind of 

 conglomerate, of minute parts, which 

 polarize vividly, some fragments ho- 

 mogeneous in color, being of a neu-- 

 tral gray, as well as some other sub- 

 stance less easy to describe, whilst in 

 some few cases there are pieces evi- 

 dently from granitic rock. Flint, when 

 seen under polarized light, does not 

 exhibit color, but nevertheless its char- 

 acter is thus best distinguished. Oc- 

 casionally I have imagined I have seen 

 some instances in which a change has 

 been undergone. I speak of this doubt- 

 fully, but certainly there is nothing 

 which has the slightest approach to a 

 metamorphosis into quaitz. It has 

 been supposed by some that an infil- 

 tration of chalcedony does take place 

 occasionally, but that must surely be, 

 if at all, before the formation of sand 

 particles. An old French writer, M. 

 Reaumur, in Memoires de V Acade- 

 7nie des Sciences^ 1 72 1 , writes : ' By a 

 coarse operation emery is reduced to 

 powder, and suspended in water sev- 

 eral days ; but nature inay go much 

 further than this, for the particles 

 which water detaches from hard 

 stones by simple attrition are of an 

 almost inconceivable degree of fine- 

 ness. Water thus impregnated con- 

 tributes to the formation of pebbles 

 by petrifying the stone, as it were, a 

 second time. Stones already formed, 

 but having as yet a spongy texture, 

 acquire a flinty hardness by impreg- 

 nation with this crystalline fluid.' 



I state this as I find it. The au- 

 thor gives no facts, so the hypothesis 

 must stand by itself. But there is 

 one point worthy of note, wherein 

 he speaks of the extremely minute 

 particles produced by mere attrition. 

 This in rounded pebbles must indeed 

 be infinitesimal, and one could hardly 

 expect to find such particles of any 

 inoment in the composition of sand. 

 Byt it must be otherwise with the 

 rough flint, as it comes from the 



