'f'rench National tnjllttite. 1 79 



The papers to be tratifmitted before the fame period. 



5th, By what means can dueHinii he prevented in a coun- 

 try' where an idea prevails, that infamy attaches to a perfoa 

 who on receiving certain injuries does not call forth the of- 

 fender, or who when called forth docs not accept the chal- 

 lenjje ? And in inch cafes, what meaiiu'es are to be purlued ? 



The papers to be fent in as before. 



The anfwers to thefe quefiions, written either in the Ger- 

 man, Dutch, Engliili, French, or Latin languages, muft be 

 inlcribed with a certain device, and tranlmitled, free of poll- 

 sgc, to Dr. Lnchtmans, at Utrecht, feerctary to the fociety. 



FRENCH NATIONAL INSTITITTR» 



Notice of the labours of the Clafs of tlie Mathematical and 

 Phyiieal Sciences during the lalt three montlis of the year (y. 



JSlatheviaticSi 



C. Delambre read the following account of the niathcma- 

 lical labours : 



A memoir on the equilibrium of arches, !)y C, Bofl\it, was 

 read. As the llones which compofc an arch mutually coun- 

 terbalance eacti other, they remain fufpended without any 

 fupport from below, all their effort being directed towards 

 the abutments, which fupport the arch, as if it formed one 

 continued bodv. 



To cnfure liie duration of an arch, it is not fufficient that 

 all the (^ones fliould be in equilibrium; the abutments ou 

 which they reft muft oppofe a fuflicicnt rcfilhmce to the 

 etlbrts the arch makes to overturn or cruiii them. 



A rellarrh into the means proper for preventing their being 

 n\-crturned conltitutes what is called the problem of the puHi 

 of arches, which engaged the atlenti(;n of feveral geome- 

 tricians of the lafl century; but they entirely netrlccied that 

 problem which has for its oljjecl the means of prevenlin* 

 crufhing. 



'I'o trv the refinance of which din'ercnt ftones are fufcepti- 

 blc, Soufflet invented a machine, which wa^ afterwards im- 

 proved by C Kondelet. 



The anlient.^ had no very certain or geometrical prirn iplcs 

 for infuring the folidity of their edifices ; at leali, no trace of 

 them is feen in the work of Vitruvius, nor is anv thinir found 

 in that work on the tignre of the Itt^nes or on that of the ' 

 womi ; which induces C. Bodiit to think that their archi- 

 te6ls, attending merely to decoration and external form, left 

 to the builders what related to the couilrudiou and foliditv, 



-M 2. iu 



