120 Rkport S.A.A. Advan* kment of Science. 



springs jiiid the entire failure of sone, such as at Griquatown and 

 Campbell.* Before the construction of the railway, the Kiniberley 

 mines used an enormous quantit}' of wood, which was brought from 

 great distances, and no efforts were made to replant denuded areas. 

 It is said tliafc as much as £40 has been paid for a wagon-load of 

 wood. Numerous cases of the effect of forests on springs have been 

 collected by Dr. J. C. Brown,! and the author can add some recent 

 cases in the Transvaal. At Agatha the water rising from a spring in a 

 thicket of trees used to be letl off l)y a furrow for irrigation : but the 

 si)ring drie ] up when the thicket was cut down. At the Iron Crowji 

 mine, near Heanertsburg. the permanent forest streams have been 

 verv considerably )'educed since the trees ha\e l)een cut down for 

 fuel, &c. 



Intimately connected with this effect on springs is the question of 

 the variety of the surrounding trees. I"nf<jrtunately this has not 

 received nearly the amount of scientific attention that it deserves, aiid 

 the rate at which the various varieties of trees .ibsorb and transpire 

 nioistui-e has been much neglected. 



Nisbet ;!: gives the lesult ut some observations made by Von Honel, 

 showing that the average transpiration of water per 100 grammes of 

 <lrv leaf substance amounted, iluring the active period of vegetation, to 

 tlie following numlx'r of kil<»gra)nmes annnallv : 



I 

 I 



Kilogrannnes. 



]Vfean average for all trees ... ... ... 69-800 



Mean average for Broaddeaved trees ... ... 82-520 



Mean average for Coiiifers ... ... ■-. 11-307 



This shows that, with the exception of the deciduous larch, 

 conifers transpire on the average only about one-si.xth to one-tenth 

 of the ((uantity of water that is evaj»orated by 1))-oad-leaved trees. 



Other trees, such as eucalypts and acacias, consume a lai-ge amount 

 of moisture, and shoid'l navev be planted in the neighbourhood of 



* Mi/ssiohKi-f/ Lofmnr.s (uitf ,S'<< /n.v in South Ajii<a, jip. 3-29 «'( srtj. 



t See Forrs't aud Molsfinr. 'X Sfi<(fics in Fotrstn/, \t]>. 76 et siq. 



