26 On Vision. 



the late progress of chemical philosophy, that the discoverer of 

 the laws of electrical decomposition ; of the composition of the 

 alkalies, eartiis and acids, supposed to he simple; of the inde- 

 pendence of the supporters of combustion; shoiild have developed . 

 a new chemical principle with respect to flame: or that he 

 should have accomplished an oI)ject on which he was employed 

 with t>reat zeal and unwearied industry for some months. 



7'hongh I have taken great pleasure in chemical inquiries, I am 

 not known as a publisher; nor should I have volunteered any ob-r 

 servations on this occasion, had I not been deeply penetrated by 

 the greatness of the benefits conferred on liumauitv by the in- 

 vention of the wire-gauze safe-lamp, during an examination that 

 1 made of some of the mines in the neighbourhood of Newcastle. 

 1 saw some hundreds of the lamps in the hands of the miners, 

 who spoke of them with a mixture of gratitude and affection 

 under the name of Davies. I should feel unworthy of perusing 

 works of ])hilosophy, if I did not find n)v heart glow at such a 

 sight, and if I did not feel some indignation when I hear the 

 merits of such a benefactor to society depreciated. 



Our great English chemical philosopher by his various bril- 

 liant discoveries laid long ago the foundation for an unperishable 

 fame ; and if his discovery of the chemical agencies of electricity 

 be regarded as the solid base of the cohunn of his scientific glory, 

 the discoveries which terminated in the safe-lamp may be re- 

 garded as its Corinthian capital, equally beautiful and useful ; 

 and this column will stand " untouched by time," when the 

 lubhish and dirt which envy and jealousy heap around it shall 

 decay and disappear: — and even should this generation neglect 

 it, posterity will not fail to crown it with civic garlands, in which 

 the evergreen oak and laurel are blended, emblems of a triumph 

 of genius and labour over one of the most destructive agents with 

 which humanity had ever to contend. 

 I am, sir. 



Your obedient humble servant, 

 Chelsea, Dec. 16, 1816. Wm. PoWELL KnigHT. 



IV. On Vision: in ylnswer fo Mr. Vater. i?;/ i\/r. Andrew 

 Horn. 



To Mr. Tillock. 



Sir, — \'V HETHEFi the ignorance and inconsistency manifested 

 bv Mr. Pater, in your number for November, be real or assunked, 

 is of little importance. One thing is certain, that " good humour" 

 never can atone for these blemishes in any writer. I hazard the 

 assertion^ that there is not one among the numerous readers of 



the 



