OF A NEW STATICAL LAMP. <)$ 



j>art of the fan's difk, equal to a circle of 15" in diameter, 

 would far exceed the greatefl luflre of the full moon ; whereas, 

 the light of a planetary nebula, of an equal fize, is hardly 

 equal to that of a ftar of the 8th or 9th magnitude. If, on 

 the other hand, we fliould fuppofe them to be groups, or cluf- 

 ters of liars, at a diflanee fufficiently great to reduce them to 

 fo fmall an apparent diameter, we fhall be at a lofs to account 

 for their uniform light, if clufters; or for their circular forms, 

 if mere groups of liars. 



. Perhaps they may be rather allied to nebulous liars. For, 

 fliould the planetary nebulae with lucid centres, of which the 

 next article will give an account, be an intermediate flep be- 

 tween planetary nebulce and nebulous liars, the appearances of 

 thefe different fpecies, when all the individuals of them are 

 fully examined, might throw a conliderabie light upon the 

 fubjec"t. 



XII. Of planetary Nebulce with Centres. 

 In my fecond catalogue of nebula, a tingle inftance of a n. Planetary 

 planetary nebula with a bright central point was mentioned j nebul * Wltii 

 and, in No. 73 of the 4th clafs, is another of very nearly the 

 fame diameter, which has alfo a lucid, though not quite fo 

 regular a centre. From feveral particularities obferved in 

 their conftruction, it would feem as if they were related to 

 nebulous flars. If we might fuppofe that a gradual condenfa- 

 tion of the nebulofity about a nebulous liar could take place, 

 this would be one of them, in a very advanced flate of com- 

 preffion. A further difcuffion of this point, however, mull 

 be referved to a future opportunity. 



IV. 



Defcription of a New Statical Lamp, zvhich of itfelf raifesmid 

 keeps the Oil at a conftant Height. By M. D'Edelcrantz, 

 of Stockholm, Member of feveral Academies and Literary So- 

 cieties, Knight of the Order of the Polar Star, %c *. 



OINCE the firft invention of the lamp with a double current Advantages of 

 of air by M. Argand, many attempts have been made to find P lacil ?S * c f e " 



iL r i • *i_ r • r -i ii , r , fervoir of a lamp 



the means of placing the refervoir of oil below the focket of below the flame* 



* Communicated by the Author. 



the 



