April 1, 1892.] 



KNOWLEDGE. 



61 



^PV AN ILLUSTRATED "^i^ 



MAGAZINE OF SCIENCE 



SIMPLY WORDED— EXACTLY DESCRIBED 



LONDON: APRIL 1, 1892. 



CONTENTS. 



British Mosses. Bt the Et. Hon. Loed Justice Fbt, 



F.R S., F.S.A.. F.L.S. 



Elephants, Recent and Extinct. Bt R. Ltdekkeb, B.A. 



Cantab 



Theories of Glacier-Motion. By the Ker. H. X. 



HuiCHissox, B.A., F.&.S 



The Great Sunspot and its Influence. B_v E. W. 



Macndee. F.R.A.S. ... 

 On the Connection between Sunspots and Magnetic 



Storms. Br A. C. Ra>taed 



Letters:— J. E. Gobe; W. T. Ltxs ; G. Ceaws)iat; 



and W. H. S. iloxcK 



The Chemical Researches of Jean Servais Stas By 



TirOHAy CoBXisH, B.Sc, F.C.S. ... 



The Life of an Ant.— n. By E. A. BriLSB 



The Face of the Sky for April. By Hbebebt Sadles, 



F.R.A.S. 



Chess Column. By C. D. Locock, B.A.Oxon 



61 



&i 



66 



68 



70 



70 



74 

 76 



78 

 79 



BRITISH MOSSES. 



By the Rt. Hon. Lord .Justice Fey, F.R.S., F.S.A., F.L.S. 

 {Co7ititiued from page 43.) 



BUT, it will be said, assuming that 

 this may be the case with one 

 ijrowth of forest, how about the 

 successive destruction of suc- 

 cessive forests ? The answer 

 is, I believe, to be found in the curious 

 change which peat undergoes, and which 

 converts it from a substance highly 

 absorbent of water into one impervious 

 to it. 



The section exposed by a peat-cutting 

 in, I beheve, almost all cases exhibits 

 two kinds of peat, the one known vari- 

 ously as red peat — or red bog, or fibrous 

 bog, or in Somersetshire as white tui-f — 

 which lies at the top, and the other a 

 black peat, which lies at the bottom. 

 The red peat retains visible traces of the 

 Sphagnum of which it is mainly com- 

 posed, and is highly absorbent of mois- 

 ture ; whilst the black peat has lost all, 

 or nearly all, traces of the minute struc- 

 ture of the cells, and is not only unabsor- 

 bent of moisture, but is impervious to it. 



In fact, it constitutes an insoluble substance which is said 

 to be scarcely subject to decay, so that it is used in Holland 

 for the foundations of houses, and is found unchanged after 

 ages, and when the buildings have fallen into decay. It is 

 even said to have remained unchanged after three months' 

 boiling in a steam-engine boiler. The broad difference 

 between these two kinds of peat may easily be ascertained 

 by anyone who wiU, as I have done, subject the two kinds 

 to the action of water. 



In Fig. 33 wUl be found a section of a peal bog, copied 

 from an engraving in the thh-d Report of the Commissioners 

 on Irish Bogs (" Parliamentary Papers," 1813-4), and 

 exhibiting the remains of three forests anterior to the 

 vegetation growing on the surface of the bog. The history 

 of the formation wiU be, I beheve, much as follows : — 



(1) We must get a watertight bottom. In the section 

 given it is said to consist of limestone gravel, but this 

 probably had, at least in its lower part, got consohdated 

 into a pan by the infiltration of insoluble iron oxides, 

 themselves often due to decaying vegetable matter, or it 

 rested on a subsoil of stiff clay. The necessity of this 

 watertight bottom is well shown by the fact that in places 

 in the Irish bogs where a piure limestone subsoU occurs the 

 bog becomes shallow and dry. 



(2) On this Limestone gravel a forest arose and flourished 

 for a considerable period, untU the natm-al drainage of 

 the area was stopped, whether by the choking up of the 

 com-se of the effluent stream, or from the aggregation of 

 vegetable matter, or from the fall in the course of nature 

 of the trunks of the trees themselves. Everyone who will 

 consider how much care our rivers require in order to 

 make them flow with regularity to the sea — who thinks, 

 for instance, of the works in the Thames valley, or in the 

 upper valleys of the Rhine — wUl see how often and how 

 easily, in a country in the condition of nature, stagnant 

 waters will arise. In the morass thus formed the Sphagnum 

 has grown, years after years, and if it has not destroyed 

 the old trees it has prevented the growth of young ones. 

 The stools of the trees buried in the antiseptic waters of 

 the Sphagnum pools have been preserved, whilst the fallen 

 trunks have, except when preserved by the like circum- 

 stance, rotted, and added their remains to the peat which 



i>trTf7f^^.U U l-.^ ga&^S£i 



j. jrsvc'lirtS t i iii 'j i M-'a S.- ^i^ 



Fig. 33. — Section of Irish Peat bog, showing the growths uf three 

 successive submerged forests. {From Third Sepori of Commissioners 

 on Irish Peat Bogt.) 



