September 7, igi 1] 



NATURE 



.15 



The Fertility and Extinction of Forest Trees. 



The mountains of Madeira exemplify perhaps mure 

 clearh than the denuded Scottish hills the " irreparable 

 [bss " which your correspondent " D. W. T. " (Nature, 

 June i) deplores in the disappearance of the Scotch fir 

 Kri si,. For not only have we exhausted our splendid 

 timber in prodigal excess of economic requirements, but 

 v., have further to face the fact that the straggling trees 

 which still survive in remote or precipitous localities appear 

 to have lost much of their former fertility, showing now 

 no tendency to spontaneous spread nor any evidence of the 

 prolific reproduction of former days. Hence we are con- 

 fronted with the absolute extinction of woods not grown 

 elsewhere — woods of very great botanic interest both in 

 themselves and in relation to problems of origin and 

 distribution. 



Madeira (Materia) was the name given originally by the 

 Portuguese discoverers to denote the densely wooded con- 

 dition of their new possession. 



The destruction of the forests began with the first 

 colonists nearly 500 years ago, and was accentuated during 

 the Spanish occupation in the second century of the island 

 history. No replanting whatever has been attempted since, 

 nor have any effective measures been put in force to stay 

 the progress of destruction. The island population, more- 

 over, has increased during the last fifty years from 75,000 

 to 150,000 people, and the land is everywhere being cleared 

 and occupied. 



Nevertheless, the introduction of the Pimis Pinaster 

 has during the last 150 years had an important influence 

 on the preservation of the surviving native vegetation, and 

 the tree has become established on the heights from 1500 

 feet to 3000 feet above the sea in surprising vigour and 

 profusion, supplying fuel and many requirements on which 

 a more durable and valuable wood would be wasted. Some 

 of your readers have seen at my mountain home the 

 stately growth of the Pinaster planted only sixty years 

 ago. The larger trees have a girth, 5 feet above the 

 ground, of 12 to 15 feet, and vary from 80 to 130 feet 

 in height. They lose all their lower branches in due 

 course, many of them standing in majestic isolation to 

 suggest the famous " Spear, to equal which the tallest pine 

 hewn on Norwegian hills to be the mast of some great 

 ammiral were but a wand." These Pinasters were giants 

 when I came into possession thirty-five years ago, and their 

 growth since has been in girth rather than in altitude, 

 though their heads have not vet reached the Ezekiel stage 

 of your correspondent " D. W. T." 



In my view we should not trust to the maintenance of a 

 single species in vigour and fertility, and hence I have 

 brought many coniferous and other trees hither to test both 

 quality and rate of growth, and thus their fitness to sup- 

 plement or supplant our present supplies. Many of the 

 newcomers, though growing into beautiful examples, do not 

 merit extensive plantation, and I have not raised any 

 specimens of Podocarpus, Widdringtonia, Libocedrus, 

 Dacrvdium, Sic, the merits of which encourage their multi- 

 plication ; but it is far otherwise with the Douglas fir, the 

 Taxodium sempervirens, the Abies Pinsapo, Cupressus 

 macrocarpa, &c, which are quite at home in their new 

 environment and congenial soil, as also with the Pinus 

 canarirnsis and the P. longifolia. The P. insignis, how- 

 ever, in this latitude is pre-eminently worthy of general 

 adoption at the elevation of 2000 feet. I received seeds of 

 this species from Kew in Sir J. Hooker's time, and one 

 of the trees from this source has attained a growth of 

 more than 100 feet in twenty-six years ; and I have a 

 goodly patch of young trees sown ten years ago which 

 Bready vary from 25 to 30 feet in height. 



But 1 have written enough to illustrate the importance 

 of planting new varieties when threatened with declining 

 fertility or extinction, though I cannot think the Pinus 

 sihestris to be in any such danger! Irreparable loss is 

 mainly the result of improvidence. 



It is interesting to note that many of the Madeira trees 

 which have become nearly sterile and almost extinct in the 

 wild state become vigorous and abundantly fertile in culti- 

 vated ground. 



The Cerasus lusitanica, the weeping Juniper (/. 

 Oxvcrdnts), Phncbc barbusana. Sic, are familiar example* 

 of reviving fertility in altered circumstances. 

 NO. 2184, VOL. 87] 



I have sent from time to time specimens of the Madeira 

 rare woods to the museum at Kew, and amongst them 

 the ebony-like laurel wood of the Oreodaphne foetens, the 

 heavy oleaceous wood of the Notaelea excelsa, and a long 

 hammock-carrying pole made of Clethra wood, are worth 

 attention. 



The Clethra arborea is happily still quite common, and 

 attractive at this season with its abundant show of fragrant 

 lily-of-the-valley-like flowers. 



Madeira, August 21. Michael Graeham. 



Non-Euclidean Geometry. 



In my " Theories of Parallelism " I expressed my sense 

 of failure in controverting Bertrand's simple proof (by 

 the consideration of infinite sectors and infinite strips) of 

 Euclid's parallel axiom. This sense of failure has only 

 increased since the publication of my little book. 



I have also come across the statement that Poincar£ 

 has proved that no Beltrami " trumpet " surface in 

 Euclidean space can completely image a hyperbolic space 

 unless it has a line of discontinuity on it. I would 

 welcome definite information about this. It seems to me 

 an important objection. Had Poincar£ this at the hack 

 of his mind when he dismissed space-theories as matters 

 of convenience only in his brilliant volume " La Science et 

 l'Hypothese "? 



There is something passing strange about the infinite 

 regions of a hyperbolic space. If K is the space-constant 

 and R the radius of a circle in Lobachewskian space, and 

 if R is exceedingly large even compared with K, then the 

 area of the circle appears as an exponential infinitude, 



K 

 something like 7rK 2 p K 



But if a regular polygon with an indefinitely great 

 number of sides (N, say) can be inscribed in this circle 

 of radius R, the area of each of the N component triangles 

 is only K 2 times the divergence. And the divergence of 

 each triangle cannot very well be supposed to exceed 27r, 

 for then the angle-sum would be 31. Hence the area of 

 the polygon appears less than 27rK : N. 



Would readers offer an opinion? 



Wrawby, near Brigg. W. B. Frankland. 



The Salary of an Assistant Lecturer. 



I have read with indignation the advertisement of the 

 City of Bradford Education Committee on p. lxiv of Nature 

 of August 17 for an assistant lecturer in dyeing at a 

 salarv of " 60Z. per annum, with additional payment for 

 evening work (two evenings per week)." 



Do the members of this committee realise that they are 

 offering to an assistant lecturer at their college less than 

 the minimum wages — 24s. a week — demanded by the rail- 

 way strikers in the North for the lowest and least efficient 

 railway employee? 



Thev may reply that their lecturer can make a little 

 more by extra work — evening work ; but so can the rail- 

 way employee, and the latter may do it without doing any 

 extra work whatever. 



According to the conditions of appointment, the person 

 appointed will be required to devote the whole of his time 

 to college work ; the hours of actual attendance at the 

 college are thirty-seven per week, the vacations may be 

 curtailed " if necessity demands it," and the amount of 

 the pavment for the evening work is not given. 



W. H. Hodgson. 



Tredethiyn, Port Isaac, Cornwall, August 22. 



Obsolete Botanical and Zoological Systems. 



1\' reply to the request of L. C. M. in your issue of 

 Vugust 3, the following references may be of interest to 

 him. "Insect Architecture," Charles Knight and Co., 

 Ludgate Street, 1845, contains a chapter upon systematic 

 arrangr-inent of insects, which contains the following :— 

 Aristotle's, Linnaeus's, De Geer's, Aldrovand's, Vallisnieri's, 

 Fabricius's, Latrielle's, Swammerdam's, Ray and Wil- 

 luffhbv's, Cuvier's, Lamarck's, Sir Everard Home's, 

 Clairville's, Leach's, Stephen's, and McLeay's classifica- 

 tions. Hoping this may be of use. M. Niblett. 



52 Oxford Road, Chesterton. Cambridge. 



