1824.] Electricity through Tubes of Water, 49 



superseded the necessity of it. — In 1823 I again introduced the 

 subject in my course at the Surrey Institution — when the experi- 

 ments and theory noticed in my former letter to you, were 

 offered in explanation — and I was induced to suppose my com- 

 munication would not prove unacceptable, by the recent in- 

 quiries of some scientific friends who were anxious to know if 

 I could explain the cause of so singular an effect — among 

 whom was Mr. Lewthwaite, the writer of the letter alluded to 

 by T. J. 



I now turn to a more pleasing part of the subject, that of 

 investigating experiments. 



"Would suggest (continues T. J.) that ' Mr. W. should re- 

 peat the experiment with the water tube. I am disposed to 

 think Mr. W. is in error, when he says the intensity (measured 

 we are to suppose by a pith ball electrometer), indicated, was 

 from 10° to 15°." The supposition in the parenthesis is per- 

 fectly correct, and I can assure T. J. I have too often repeated the 

 experiment, and made too many notes upon the subject in con- 

 junction with my electrical friends, to be in error. I have very 

 frequently succeeded in the experiment with a quart jar, 

 when the electrometer has indicated an intensity of only 10°, 

 but not invariably ; hence I stated in my letter, " an intensity 

 of from 10° to 15° is generally sufficient." Had I noticed all 

 the minute peculiarities I have observed on this head, my 

 communication would have been much too long for insertion, 

 and as no particular point turned upon the question, I con- 

 sidered it sufficient to express myself in terms to be understood 

 by an Electrician, without unnecessarily intruding upon your 

 valuable pages. I must, however, inform T. J. that the success 

 of the experiment, with a low degree of intensity, will greatly 

 depend on the quality of the gunpouder, as well as the care 

 taken to prevent the dissipation of the electrical fluid, for with 

 very coarse powder I have been unable to perform the experi- 

 ment at all. 



T. J. lastly observes, " it would have been more satisfactory 

 if the degree at which the jar spontaneously discharged itself, 

 had also been stated." This I confess myself at a loss to 

 comprehend, for I have always found the spontaneous discharge 

 of a jar, when mounted in the usual way, to depend as much 

 upon what may be termed casual circumstances, as any ex- 

 periment connected with electricity. At one time I have seen 

 a spontaneous discharge take place at 50° ; at another, the 

 same jar, with the same electrometer, has been charged to 90°, 

 without a spontaneous discharge. This suggestion, if reduced 

 to practice, would be rather an expensive one to me, as my 

 jars are all furnished with internal paper rims, according to 

 Mr. Singer's plan — the metallic rods communicating with the 

 inner coatings are passed through stout glass tubes, cemented 

 New ISeries, v o L. VI 1 1. E 



