O.'JO Bnlavtan Soc'icf-y at Haarlem, 



Aill obfcure or dubious in this refpccl ? and. Can confe>» 

 quences uletul for th^culuvation of trees and plants be de- 

 duced from what has been akeady confirmed on this fubjeft 

 •by decifive experiments? 



" n. As it is probable, if more attention were paid to 

 thofe phyficai caiifes which force back fniuke into chimneys, 

 that means might be dcviftd to prevent aj)artments from 

 being cxpofed to it, except in the cafe when the chimneys are 

 expofed to violent winds, the Society requires : 



«' I ft, A theory or brief phvfical explanation of the caufes 

 which force back fmoke in chimneys, or prevent it from 

 afcending. 



*' ad, Rules, deduced from this thcor}-, for building chim- 

 ney's, and in which precepts mult be given, taking into con- 

 fidcration every poihble circumllance to prevent apartment^ 

 from being expofed to fmoke. 



*' III. What indigenous ph»nts, hitherto not iifcd, are ca- 

 pable, according to well-alterted experiments, of producing 

 good dye ftufis, and might be employed with advantage for 

 that parpofe ? and, What foieign plants might be reared iu 

 the Icaft fruitful and little cultivated parts of the republic, in, 

 order to procnre dyes from them ?" 



The anfwers to thefe three queftions muft be tranfmitted 

 to the Society before the firft of November i8oi. 



For the prefcnt year, the Society has propofed the fullow- 

 ing queltions : 



"I. What can we confider as proved, or as highly pro- 

 bable, accnrdinir to tlie latcil aftronomical obfcrvations, par- 

 ticularly thofe of Herfchel and Sehroter, in regard to the. 

 extent of the univerfe, and the order in which the heavenly 

 bodies liand ?" 



In the anfwers to this quefiion, the Society requires that 

 the authors will give a (hort and comprehenfive view of the 

 prefcnt (late of a!tronomy in regard to this point; and fliow 

 how improbaV/le or ill founded fomc of the hypothefes formed 

 on this fubjett are. 



*■' II. How far do we know, according to the lateft im- 

 provements in the phyfiology of plants, in what manner the 

 •di&rent kinds of earth promote the vegetation of plants? 



and^ 



