464 Proceedings of Philosophical Societies. [Dec. 



would such information suggest for preventing thai propagation 

 of such insects, or for extirpating them 1" 



7. " Has experience clearly proved that there are certain trees 

 and plants, particularly of the most useful species, which cannot 

 vegetate when close to each other ? And in this case what expe- 

 riments can be produced as proofs ? Can this antipathy between 

 some species be any ways accounted for by what we know of 

 the nature of plants, and what useful information does it supply 

 us with for the cultivation of trees and useful plants ? " 



8. " What are the insects most hurtful to trees and shrubs in 

 forests ? In what consist the injuries they produce ? What are 

 the remedies proper to prevent such injuries, or to remove 

 them ? " 



9. " How far are we acquainted with the economy of moles, 

 and what means does it suggest as most efficacious for ridding 

 lands of them where they prove destructive ? Are there, on the 

 contrary, any observations tending to prove that moles are ever 

 useful by destroying other vermin, and how it may be known 

 •when moles ought to be tolerated ?" 



The Society have in preceding years proposed the following 

 14 questions to be answered before Jan. 1, 1821. 



1. " What advantages have resulted to medicine from the 

 extension and reformation of chemistry, since the time of Lavoi- 

 sier and his successors, by making us better acquainted with the 

 action of the usualmedicines, and how can we acquire a certain 

 knowledge of the chemical action, hitherto unknown, of certain 

 medicines ? " 



2. " How far can it be proved by accurate observation that 

 the diseases prevalent in the Netherlands have, since a certain 

 lapse of time, changed their nature : what are the physical 

 causes of this change, especially as dependant upon the manner 

 of living which is different from what it used formerly to be?" 



3. "What is the state in this country of the prisons in gene- 

 ral ? What are the defects which a scientific examination might 

 point out in them ? and what methods should be employed to 

 improve the health of the prisoners ? " 



4. " What are the most easy and proper methods to which 

 seamen should have recourse to preserve themselves as long as 

 possible in case of shipwreck, and thereby to increase the possi- 

 bihty of their being saved ? Is there any method more efficacious 

 than the scaphandre described by M. de la Chapelle ? What 

 measures too ought to be taken to enforce the adoption, in every 

 case, of the very best means for retarding the submersion of 

 shipwrecked persons ? " 



5. " What are the certain signs of the real epidemic (epizootie), 

 tvhich for more than 30 years has made such ravages in many 

 southern countries, and likewise our ov/n ? Are there sufficient 

 reasons to determine that the said malady never takes place with- 



