190 Foreign Literature a /id St cn<>. 



the comet, and may tend as much to diminish as to increase 

 the distance. It is therefore not impossible, that at some 

 time the comet may pass at a very small distance from us. and 

 even so near, that its atmosphere may be in contact with our 

 globe. — Idem. 



55. Monochromatic Light. — L pon the discovers" of Dr. 

 Brewster, that the flame of alcohol diluted with water, con- 

 sists chiefly of homogeneous yellow rays, and his suggestion, 

 that it would afford a monochromatic lamp useful for obser- 

 vations with the microscope. Mr. Talbot has constructed a 

 lamp, which affords an abundance of yellow light for a long 

 time. A cotton wick is soaked in a solution of salt, and 

 when dried, placed in a sprit lamp. By employing ten 

 of these wicks, which were arranged in a line in order to 

 unite their effect for a microscope, a light was obtained little 

 inferior to that of a wax candle. Its effect upon all surround- 

 ing objects was very remarkable, especially such as were red. 

 which became different shades of brown and dull yellow. A 

 scarlet poppy was changed to yellow, and the beautiful red 

 flower oi the lobelia fulgens, appeared entirely black. — 



: 3. Volcano?. — Have the elevating effects of volcanic power 

 been perceived on the Eastern side of the American conti- 

 nent I 

 E.r1ract of a letter from G. Poulett Scrope. Esq. to the 

 Editor, dated. London. March 21. 1S27. 

 In replv. I have to thank you particularly for your very 

 liberal offers of contributing any facts, which may come to 

 vour knowledge, bearing upon that peculiar branch of the 

 historv of the globe, which I have applied myself to investi- 

 o-ate. Such communications. I beg to say. will be most val- 

 uable to me. as materials for a second edition of the work* in 

 question, which will probably at some time another be called 

 for. Mav I take the liberty of hinting a few observations, 

 connected with tins subject, to which if the attention of some 

 of vour numerous geological friends and correspondents were 

 directed, it must. I conceive, elicit some very important infor- 

 mation. The volcanic force seems to have developed itself 

 verv rarelv. if at all. under its most usual form, on the East- 

 ern side of the great longitudinal axis of America, whether 



■ C oriiiderations on Volcanos. &c.' : 



