285 JUNCTURE FOR METALLIC PIPES. " 



Elecfiral c?- 99, in a paper on electrical attraction? and repulsions, the 

 antbor, in mentioning the experiment with the tumbler and 

 balls, says, " the glass held between the two hands is no- 

 ** thing more tlian a Leyden phial." - 1 must beg leave to 

 add, that any one may convince himself of the truth of 

 this assertion, by only usinj:;^ a glass jar capable of holding 

 a pint and half, or two pints, instead of a tumbler. If, af- 

 ter grasping it in both his hands, and inverting it over the 

 pointed brass rod inserted into the conductor, he removes 

 one hand, and puts it quickly to the bottom of the jar, he 

 will receive a shock. The first time I tried this experiment, 

 > , I received so strong a shock, that I was afraid of repeating 



it for some time. However, I have repeated it several times 

 this afternoon, and in the presence of a second person, who 

 also received several shocks from it: once in particular he 

 complained of having a strong shock through the stou^ach, 

 and at the same moment I had observed a flash pass between 

 his stomach and the middle of the glass jar. I have fre- 

 quently received several small shocks, but if it discharges 

 itself at once, the shock is so strong as to be exceedingly 

 disagreeable. A larger jar no doubt would produce more 

 powerful effects. If any thing I have said appears to be 

 worthy a place in your Journal, I shall be happy to gee it 

 inserted ; at all events an answer to the queries proposed 

 will much oblige. Sir, 



Your obedient humble servant, 



L. 0. C. 



ANSWER. 



Junctures tor The juncture recommended in the preceding letter will 

 me'uilic tubes, ^^ Joubt answer on many occasions, but my correspondent 

 will not find it a very easy matter to make it lit with accu- 

 racy. If the middle part of the connecting tube were oc- 

 tagonal, it would admit of the use of a key, which should 

 be made with a joint in the middle, to screw or unscrew it; 

 and this would often be of advantage. The rim of Dr. 

 Henry's stuffing box, which is certainly a preferable junc- 

 ture, might Uke-.vise be made of this shape foV the same 



' I know 



