'On the Spots of the Sun, ^c. 39 



tnotion, in confequence of having wheels of different diame- 

 ters, and for covering the rider from th* fun, may feem to 

 Tefemble fome of our prefent carriages more nearly than has 

 been fuppofed, yet do notfo flrikingly differ from thofe which 

 were common among the antlents as to excite much furpnfe. 

 But the latter appear, indeed, extraordinary : they poffefled 

 all the advantages, as it fhould feem, of the chariot way- 

 wifer, which has been believed to have been firft invented 

 by fome members of our Royal Society about the year i66a; 

 and of the pedometer, which is at prefent manutadured, I 

 think, under a^patent. 



I am. Sir, 



Your obedient fervant, 

 London, R. HeKON. 



Oftober 8, xSot. 



VII. Ohfervations on the Spots of the Sun, and the Nature of 

 the Light of that Luminary. By M. VON Hahn *. 



\JuR experience of the various effefts produced by the 

 fun's rays, and particularly the doftrine of latent heat and 

 fpecific heat, feem to confirm the opinion that light is an 

 adual body which ftreams forth from the fun, and which is 

 conneaed, in a variety of ways, with the bodies of our 

 earth. The determination of the following quettion, which 

 bclontrs peculiarly to chcmiftry, "Whether the fun be aftu- 

 ally a°burnintr body, or only attrafts the illuminating matter 

 from the furr°unding expanfe of the univerfe r" may receive 

 fome illuftration from continued obfervations made on the 

 bodv of that luminary. 



One great difficulty here is, that the fun has a peculiar 

 light, and we are accuftomcd only to confider objefts which 

 almoft continually receive their light from without, and 

 which commonly produce fliadows more or lefs perceptible 

 according to the dilTerent diredions and ftrength of the light 

 which falls upon them. Now our eyes, being accuftomed 

 to (hadows and projcaing images, by beholding an uncom- 

 mon kind of illumination arc thrown into embarraflfment, 

 and cannot bring the images in harmony with fenfatioii, the 

 bafis of all perfpicuity. 



One may obferve the fun a long time without dircoverinff 

 any other fpots than thofe which are common. The firft 

 view, therefore, of the fo called folar faculae produces an 



••♦ From Profrjfor Bodc'i AJl.onomical Almanac for the Year 1796. 



C 4 agreeable 



