DISORDERED EYES. 1 97 



( €n the Mayn, whofe name indeed I do not know. He 

 fells them in pairs, at a half louis-d'or the pair, which 

 t think a very moderate price, as nothing can be more 

 convenient. [Here the author enters into a minute 

 defcription of every parr of this pocket machine. But 

 they are how fo common as to render the infertion of it 

 liere unneceflary,. They are to be bought at every tm- 

 Hic t > in London, They fold up like a fan, into a tin 

 ca - and when taken out may be fixed to a candle of 

 any thicknefs by means of Aiders that comprefs the 

 pieces of brafs which inclofe it, and that fupport the 

 green filk expanded into a circle.] They may be fo 

 fixed to two candles on a card- table, that of the four 

 playeTs every one fits in a fhade apart. The ufe they 

 Lave been of to me on all occafions (for they, my eye- 

 ci ps, and glafs eyes, are my conflant travelling com- 

 panions) a thoufand times exceeds the price they 

 co& me. 



M. Campe fays that he found no relief from a pair 

 ©f fpeclacles fet in leather, as the feeing through the 

 glafles required a greater exertion of the ocular nerves. 



Perhaps the fault might be that the glafles were too 

 clofe to the eyes. For five years paft I have made ufe 

 of two glafles when I travel in rough weather, which 

 I caufed to be fet in a rim of horn, a full inch in 

 breadth, and thefe again fixed in leather, whereby the 

 whole light is covered, but fo as that between the eye 

 and the glafs there is a conliderable diftance. Armed 

 with this vizor, I have frequently, even in winter, per- 

 formed long journies on horfeback, or in an open car- 

 riage, without finding my eyes the worfe for it after- 

 wards, or feeling any particular flrain upon the fight. 



03 Ie 



