Nov. 1, 1885.] 



o KNOWLEDGE ♦ 



sheep, or fastened to the legs of passing cows and horses. 

 Being rubbed off by the discontented bearer on the next 

 bush or hedge, often enough in a nice little cake of 

 fruitful manure, the fortunate seeds take root at once under 

 fresh and favourable circumstances, and often prove the 

 precursors of a strong and healtliy future stock. In 

 hound's-tongue, tlie adhesive little burrs cling even naore 

 tightlj- to the passer-by, and are liable to be carried to 

 still greater distances from the jiarent plant. The burr 

 of the burdock cousi.sts of a whole head of flowers and 

 fruits, which separates readily from the dry stalk, and 

 fastens itself firmly to the hair or wool In- means of its 

 very hooked and clinging bracts. In tropical countries 

 these bids for cheap carriage are still more fi'equent and 

 ti'oublcsome than in our own poor little northern flora. 



Some very advanced plants go so far as actually to 

 disseminate their own seeds, or even to bury tiieni bodily 

 under gi-ound. There is a common little English weed, 

 the wall-cress, abundant everywhere on banks and in dry 

 places, whose pods, especially when touched or shaken, 

 roll \ip elastically, and scatter the tiny, bullet-like seeds 

 to a distance of some sis or seven feet by their powerful 

 impulse. The capsules of the balsam similarly eject the 

 seeds for a considerable length, and everybody must have 

 noticed the crackling of the gorse-pods on bright autumn 

 days, by which means the small beans within are thrown 

 out forcibly with no little violence among the surround- 

 ing thickets. The squirting cucumber of Southern 

 Enrojie, if lightly touched when quite ripe, breaks off at 

 the stalk with a slight bang, and scatters its seeds and 

 their surrounding pulp not infrequently in the face and 

 eyes of the too-intrusive visitor. More remarkable still 

 is the plan adopted by the subterranean clover, in which 

 the undeveloped flowers in the centre of each head act 

 as a sort of insinuating corkscrew, and, screwing slowly 

 downwards, bury the pods of the fertile blossoms at la.st 

 far beneath the surface of the close-cropped turf. In 

 the familiar pea-nut of American youth the same 

 cunning device is carried to a still further pitch of 

 perfection with Yankee ingenuity ; for the so-called nuts 

 are really subterranean pods, produced by self-fertilisa- 

 tion upon simple bud - like underground flowers, and 

 therefore, as it were, ante-natally buried. In these last 

 cases the object is, no doubt, rather to escaj e the notice 

 of enemies than to ensure dissemination in the ordinary 

 sense, for mere purposes of rotation or dispersal. 



Last of all, we have to remember that water aids 

 largely in the dispersion of seeds, especially for marshy or 

 seashore plants. Many fruits of fresh-water kinds have a 

 smooth rind with an oily juice, which the water cannot 

 penetrate, and they are carried down by the current from 

 one spot to another, a point particularly important to 

 shallow water or swampy species, as the cour.se of the 

 stream is constantly altering, and the ponds and back- 

 waters are continuallj- drying up in the hot weather. The 

 sea has transported the cocoa-nut, with its thick shell and 

 hairy covering, almost impervious to salt water, among all 

 the coral reefs and lagoons of the Pacific. Other plants hr.ve 

 been carried by the Gulf Strecm from the shores of Ame- 

 rica to the lakes and tarns of the Hebrides, or from the 

 islets of Bermuda to the marshes of the west coast of Ire- 

 land. It is probable, indeed, that while wind is on the small 

 scale the great disperser and carrier of seeds, the sea has 

 been in a wider fashion the chief disseminator of the more 

 generally-dispersed groups fver the face of the earth. 

 Onlj- those plants whose seed can stand long immersion in 

 Bait water are liable to be found in any great numbers 

 over wide tracts of land dissevered by the ocean, or on 

 newly-raised islets in the midst of the sea. 



COAL. 

 By W. Mattieu 'Willi.^ms. 



I— WHERE COAL IS FOUND AND WHEN PRODUCED. 



HAVE been very rude on more than one 

 occasion during my lifetime. I have said, 

 " Sir, your education as an Englishman has 

 been shamefiilly neglected," to men who 

 read Homer in the original for seaside 

 recreation, who know all the irregular Greek 

 verbs, who can scan, construe, and write 

 Latin verses ; even to men who manipulate the differen- 

 tial and integral calculus as glibly as a banker's clerk 

 can sum up money columus, and who have been dragged 

 to the very brink of cerebral meningitis, by dons, tutors, 

 coaches, and examiners. I have perpetrated this rude- 

 ness finding that these Englishmen knew little or nothing 

 about the Englishman's peculiar mineral, coal. In some 

 cases my rudeness was ajiplied to men whose incomes 

 were largely derived from royalties on coal that was then 

 in the course of working on their own estates. 



An amusing example of this common habit of neglect- 

 ting common homely things was afforded by a visit of the 

 Earl of Dudley (then Lord Ward) to the Birmingham 

 and Midland Instittite in oiir early days, when we were 

 located in the humble premises of the old Philosophical 

 Society in Cannon-street. I was showing him the collec- 

 tion of local fossils in the museum of the Society. The 

 massive lumps of coral especially interested him. " Very 

 fine, very choice; brought from the tropics, of course," he 

 exclaimed. "When I told him that they came, not from 

 tropical seas, but from the rocks upon which Dudley 

 Castle is built, and that the Dudley limestone which 

 yielded so large a revenue to his lordship was chiefly 

 composed of these corals, he eyed me very qiieerly and 

 suspiciously ; but when at last he found that I was quite 

 in earnest, and was backed by a clerical friend who came 

 with him, he was hugely amused at himself, and resolved 

 to give more attention to Dudley corals than he had done 

 hitherto. 



Although it may not be the case that all the readers 

 of Knowledge are receiving royalties from coal-seams on 

 their private estates, there are certainly none of them 

 who are not receiving large benefits from the coal which 

 is raised and variously worked on the common estate of 

 the British nation. This is even the case with the 

 colonists and foreigners who read this magazine. All, 

 therefore, should follow the sensible example of Lord 

 Ward, and resolve to become better acquainted with so 

 important an element of their national patrimony. 



The object of this series of papers is to supply that 

 kind and amount of information concerning our specially 

 English mineral fuel which every intelligent Englishman 

 should possess. 



Such information includes a general elementary ac- 

 quaintance with the geological relations of coal deposits 

 and their probable origin, without struggling with 

 recondite technical details; a general knowledge of how 

 coal-mines are sunk and worked, and of the social con- 

 dition of the workers ; and something about the physics 

 and chemistry of coal itself, and the wonderful multitude 

 of useful and curious products which f.re now obtained 

 by the distillation of coal and the chemical transformations 

 of the distillates. 



At the outset it will be is ell to sweep aside a widely- 

 spread illusion concerning the geological occurrence of 

 coal. Our ordinary coal, broadly sj caking, belongs to one 

 geological period or Ecj-ics of j-ccks, and this has sccf rding'y 



