and other Substances by Electricity. 23 



(four inches long,) from the outside of the jar to the extremity 

 of the chain. Discharge the jar thi-ough this circuit. 



Should there occur different results in those experiments, 

 (as I am persuaded there will,) why did Mr, Howldy not men- 

 tion such essential particulars ? Or are we to conclude from 

 his silence, that he entertained just notions of the nature of 

 the experiment, and that this circumstance was too trivial to 

 notice ? 



With respect to the method in which the wooden peg is 

 used, I am aware that it will answer very well if regulated 

 upon the principles stated in my paper : — that is, when the 

 moisture it contains in a transverse section is proportioned 

 to the charge transmitted ; and that, whether the point be 

 sharp or blunt ; and in whatever part of the circuit it may be 

 placed. If its being « very dry" were essential to the success 

 of the experiment, it appears strange, that when it possessed 

 that quality in a superior degree, by " two or three experi- 

 ments," it should be " rendered useless." Its having a sharp 

 point too, may possibly be the means of its possessing pro- 

 perties which I have not seen ; especially as it appears to have 

 been used in that shape by the celebrated electricians Dr. 

 Watson and Mr. Wilson more than fifty years ago. 



I should however recommend those" persons who use a 

 piece of wood, to have it somewhat longer than that described 

 by Mr. Howldy, for fear of meeting similar disappointments 

 to those which he met with when varying the distance between 

 the outside of the jar and the extremity of the chain with high 

 intensities ; as it is possible that the peg may be shorter than 

 the striking distance. 



Whenever an electrical discharge is transmitted throu-Th 

 water, for the purpose of igniting gunpowder, the length *of 

 the aqueous column ought always to exceed the strikino- di- 

 stance ; for if the wires which 'enter the extremities of the 

 column are brought too near each other, the electric fluid 

 will dart from one to the other with very little interruption 

 and in all probability will scatter rather than ignite the o-un- 

 powder. ^ 



To insure success, the column or train of water, or any 

 substance containing it, such as wood, twine, silk, paper, &c., 

 should never be shorter than six inches ; and the thickness or 

 quantity of water contained in a transverse section must al- 

 ways be regulated according to the nature of the charge ; that 

 is, to the quantity and intensity of the electric fluid employed. 

 When a small jar is used for this purpose, then the strip of 

 water must be very thin, or narrow : if a larger jar be used, 



the 



