96 Mr Davidson's Description of a Syphon Lamp* 



If this dove appeared at certain times of the year at Alexan- 

 dria, it might do so also at Palestine. In that case, the authors 

 of the Psalms and Proverbs would be well acquainted with it, 

 and their countrymen readily understand what bird it was, when 

 they had occasion to mention it. 



This bird seems to have some resemblance to the passenger 

 dove of America, which goes southward and northward, in im- 

 mense flocks, at certain times of the year ; and, like all other spe- 

 cies of dove, has uncommon strength of wing, and can fly long 

 and far without wearying. 



Upon the whole, we are perfectly convinced, that the deror 

 of the Hebrew scriptures is not a swallow, as many have under- 

 stood it, but a species of wild pigeon. It is very likely to be 

 one of three species now mentioned ; but we would require to 

 know more of the history of each, before we should be able to 

 say which of the three it was. 



Description of a Syphon Lamp, with Figures. By Laurence 

 Davidson, Esq. Surgeon, Dundee. Communicated by the 

 Author. 



In performing some experiments last winter, I was struck with 

 the possibility of rendering the syphon far more extensively use- 

 ful, by attaching it to a float capable of supporting it, without 

 resting at all on the side of the vessel, as it does in common cases. 



In the usual application of the syphon, the eff^ect of the fall 

 of the liquid in the vessel is evidently to bring the two columns 

 of liquid in the legs of the syphon nearer and nearer to the same 

 length; and, consequently, to diminish the quantity of liquid dis- 

 charged in a given time. 



Now, if the syphon be kept floating, it is evident, that, though 

 the liquid falls in the cistern, the diflerence between the length 

 of the two legs remains the same ; and consequently (cateris pa- 

 ribiLs) the quantities of liquid discharged in equal times will be 



equal. 



Of the various applications of which the floating syphon is 

 capable, a very simple one is for a lamp which may be used 

 either with or without a wick, and which has been found to burn 

 for months together with a uniformly regular flame. 



