462 I'HILOSOPHICAL TRANSACTIONS. [aNNO 17/8. 



Paris and Greenwich, both from the beginning and end of that eclipse, 9" 20^. 

 Whence the difference of the meridians of Greenwich and Leicester 4"^ 39\ 

 If we take the mean of all these computations, we shall have the difference 

 between the meridian of the observatory at Greenwich and St. Martin's church 

 in Leicester, 4"" SS'' of time very nearly. 



XLVII. A ready ivuy of Lighting a Candle, by a very moderate Electrical 

 Spark. By John Ingenhomz, M. D., F.R.S. p. 1022. 

 It has been long known that an electrical spark will kindle spirit of winej 

 especially when previously warmed; and that vitriolic aether will be kindled by a 

 very moderate spark, even when cold. However, 1 never saw an electrician who 

 made a common use of this experiment to light his candle when he had occasion 

 for it. The reason is, because though it may be done without much danger of 

 failing in the attempt, yet it requires some trouble to prepare every thing neces- 

 sary for making the experiment answer with certainty. Besides, agther is very 

 precious, and is easily lost by evaporation before the electric power is excited, or 

 before every thing is quite ready for performing the experiment. 



I used to light my candle a good while ago by the explosion of a small jar (by 

 small I understand one v\hich has 8 or 10 inches of metallic coating, or even 

 less) in the following manner. As I often amuse myself with electrical experi- 

 ments, I have always an electrical machine, ready for action, fixed on a table in 

 my room. When I have occasion to light a candle, I charge a small coated 

 phial, whose knob is bent outwards, so as to hang a little over the body of the 

 phial; I then wrap some loose cotton over the extremity of a long brass pin or a 

 wire, so as to stick moderately fast to its substance. I next roll this extremity 

 of the pin, wrapped up with cotton, in some fine powder of resin (which I 

 always keep in readiness on the table for this purpose, either in a wide-mouthed 

 phial or in a loose paper) : this done, I apply the extremity of the pin or wire to 

 the external coating of the charged phial, and bring as quickly as possible, the 

 other extremity, wrapped round with cotton, to the knob: the powder of resin 

 takes fire, and communicates its flame to the cotton, and both together burn 

 long enough to light a candle. As I do not want more than half a minute to 

 light my candle in this way, I find it a readier method than kindling it by flint 

 and steel, or calling a servant. 



I have found, that powder of white or yellow resin lights easier than that of 

 brown. The farina lycopodii may be used for the same purpose; but it is not so 

 good as the powder of resin, because it does not take fire quite so readily, 

 requiring a stronger spark not to miss; besides, it is soon burnt away. By 

 dipping the cotton in oil of turpentine, the same effect may be as reatiily 

 obtained, if you take a jar somewhat greater in size. This oil will inflame so 



