288 Magnitude of small celestial bodies^ 



Other caufes (II.) Many o(her caufes will have an influence on the ap^ 



customers?" parent dIameler of tlie furious difks of the ftars, fuch as the 

 goodnefs of the fpecula and lenfes ; but they are fo far within 

 the reach of our knowledge, that with a proper regard to 

 them, the conclusion he has drawn in Rem. (2.) " that un- 

 der the fame circum fiances their dimenfions are permanent," 

 will (till remain good. 



Similar experiments were made on the fpurious diameters 

 of terreftrial objects, namely filver globules, which afforded 

 the following remits : 

 Spurious ditks (I.) The terreftrial fpurious diflcs of globules are his than 



of globules are the real difi whereas we have feen, in Remark (1.) of 

 fmalJer than the , ' . *", ' , \ ' 



real difks. the celeftial fpurious di&s, that thefe are larger than the real 



ones.* 

 Larger magni- ( 2 ) The lefs globule has the Iargeft fpurious difk. This 

 tudes ; give larger agrees with the fpurious difks of celeftial objects : the ftars of 

 *' ' ** the flrft, fecond, and third magnitude, having a larger fpurious 



difk than thofe that are of inferior magnitudes, 

 coloured like the (3.) With refpecl to colours, the terreftrial alfo agree with 

 celeftial » t ne celeftial fpurious diiks. 



Lefs with ("M The. fpurious diameters of the globules, like Ihe fpu- 



greater mag. rious difks of the ftars, are proportionally lefTened by in- 

 powerj creating the magnifying power, and increafed when the power 



is lowered. 

 But not propor- (^*) When the eftimations are compared with the powers> 

 tiooally. it will aHb be feen that the increafe and decreafe of the fpu- 



rious diiks of the globules is not inverfely as the powers, but 

 in a much lefs ratio. 

 Power afts (°*-) The effect of magnifying power is unequally exerted 



more on fmall on fpurious diameters; and that, as with celeftial objects, fo 

 difks, Wlt ^ terreftrial, this power a6ts more on the fmall fpuriou* 



ditks than on the large ones, 

 and diminution ( 7 The fpurious terreftrial ditks alfo refemble thofe of the; 

 of apertwre i ftars, by increaiing when the aperture is lefiened, and de- 



creafing when it is enlarged, 

 greater on fmaH (8.) By thefe experiments it is proved, that the increafe 

 **&*• and decreafe of the diameters occafioned by different aper- 



tures is not proportional to the diameters of the fpurious dilks. 



* It appears from the context, that this arifes from the terref- 

 trial fpurious difks being formed by the fmall fpot of reffe&ed light 

 from the metallic globule, am! not from its whole diameter. 



