Scientific Intelligence. — Botany. 191 



of the inferior oolite ; then great masses of oolite and compact 

 limestone ; a thick bed of contorted, unstratified, rather crystal- 

 line, hmestone, without shells ; and above this, near to Solothum, 

 an upper Jurassic deposite, with ammonites, encrinites, croco- 

 diles, and tortoises. Dr Bou^ is of opinion that the Swiss Ju- 

 ra does not contain any Jurassic deposites newer than the coral 

 rag ; and further, that the equivalent for the coral rag is near- 

 ly wanting in the German Jura. 



BOTANY. 



21. Signs of Increase, Maturity., and Decay in Trees; by 

 M. Baudrillac. — The qualities of wood depend much on the 

 state of the tree when cut down. It appears from the experi- 

 ments of M. Hartig upon wood applied as fuel, that trees which 

 have attained maturity without passing into decay, are the best 

 for the production of heat. Thus the value of an elm of 100 

 years is to that of one of 30 years, as 12 is to 9 ; that of an ash of 

 100 years to one of 30 years, as 15 to 11. When the trees begin 

 to decay, their value rapidly diminishes : thus, if an oak of 200 

 years yields wood worth 15 francs per corde, a tree of the same 

 kind passing to decay yields wood only worth 12 francs. When 

 the wood is used for other purposes, the advantages conferred 

 by a mature and healthy state are still more considerable. The 

 common elm, growing in a forest, and in good earth, acquires 

 its full increase in 150 years ; but it will live many ages, even 

 500 or 600 years. Large forest elms are cut down with ad- 

 vantage when of an age between 100 and 130 years, and then 

 furnish a large quantity of building wood. The duration of the 

 life of the elm depends much upon the soil ; in a dry soil it be- 

 comes aged, as it were, in forty, fifty, or sixty years. Elms which 

 have been lopped live for a shorter period than the others. 

 Those which grow by the roadside, or in their plantations, may 

 be cut when seventy or eiglity years of age. In general, the 

 increase of hard woods, as the oak and elm, is small at first ; it 

 successively augments until the twentieth or twenty-fifth year, 

 is then uniform until the. age of sixty to eighty years, after 

 which it sensibly diminishes. For these and other reasons, it 

 is important that trees should be cut down when they are at 

 their mature state, and not simply when they undergo no fur- 



