of Secret Writing. 101 



are accompanied by a known sentence, still less to write an 

 answer to them, such as may be read by means of the key in 

 which they are ciphered : and least of all to compose those keys, 

 or any other key, upon the principles here applied to secret 

 writing ; for every one of these conditions must be fulfilled before 

 the alleged advantages of the method are proved to be illusory. 

 The first person, in any country, who accomplishes them all, and 

 makes known the result of his researches through the channel 

 ofthisjournal,orby a communication addressed to the author, 

 on or before the last day of December, 1822, shall immediately 

 receive one hundred pounds ; or should he do no more than 

 decipher Nos. 17 and 18, he shall immediately receive fifty pounds. 



Art. IX. Description of an improved Lamp, invented btf 

 Mr. S. Parker. 



The subject of light, during the last few years has engaged 

 much of the public attention from the introduction of gas. 

 This beautiful light has not, however, so far superseded 

 oil, as to render a more perfect lamp undesirable. The lamps 

 ROW in use for the dinner-table, for reading, or for evening fa- 

 mily occupations, have various objections which it has been 

 the design of the inventor of the SinumbraLamp to overcome. 



The first imperfection that strikes every one who uses the 

 French lamp, perhaps the most convenient and perfect, is the 

 broad line of shadow cast from the ring oil-reservoir just about the 

 level of persons* faces sitting round the dinner- table, throwing a 

 gloom over their countenances where even brilliancy is desirable. 



The second is the glare of light cast upon the table from its 

 not passing through any medium to soften or refract it, which 

 i« very injurious to the eyes, and unpleasant when the brightness 

 of the flame from underneath the burnished ring-reservoir flashes 

 on the eye on bending forwards or stooping. 



The third imperfection which applies to all lamps is the waste 

 of light where it is useless, and the total want of economy in its 

 distribution. 



The first is obviated by the new form given to the ring oil- 



