366* ELECTRICITY. 



the communication between the water of the tube 

 and the knob of the jar. On making the discharge, 

 which must pass through the small quantity of 

 water in B, and through the table F, both imper- 

 fect conductors, the electric fluid comes out at F, 

 in the form of a dense stream, which generally fires 

 the gunpowder. 



Practical Rules concerning the Use of the Electri- 

 cal Apparatus, and the performing of Expe- 

 riments. 



It often happens, that young electricians are at 

 a loss to assign the reason why some experiments 

 do not succeed with them. They are in pos- 

 session of good instruments ; but from some cir- 

 cumstance or other not being attended to they are 

 quite useless in their hands. This, indeed, can be 

 remedied only by practice ; and it is by long use 

 that the electrician, as well as the practitioner in any 

 other art or science, becomes so good an operator, 

 as to use his instruments to the best advantage. 

 A few rules are, however, useful to guide him in his 

 operations; and although these alone are in- 

 sufficient to make a person a complete practical 

 electrician, yet, when accompanied with the actual 

 management of the apparatus, they facilitate the 

 use of it, and render the performance of the 

 experiments more accurate and expeditious. 



The first thing that the young electrician should 

 attend to is the preservation and care of his instru- 

 ments. The electrical machine, the coated jars, 

 and, in short, every part of the apparatus, should 

 be kept clean, and as free as possible from dust 

 and moisture. 



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