Intelligence and Miscellaneous Articles. 



75 



The experiment may be varied by placing the two coils in the 

 same vessel, and measuring, on the one hand, the sum of the heats 

 created by the inducing and induced currents, and, on the other, that 

 which is produced in the external resistance 6. This is given by the 

 formula 



a 



The values of I' are deduced from this ; and it is found, as we shall 

 see in the Table, that they satisfy the law 



Ma 



1 = 



N + /3+0* 







M = 



87-23 



, N 



+/3 = 



= 13*00, a =0*47. 





t. 



I'. 



i. 



Sum. 



Ob- 



Calcu- 



Ob- 



Calcu- 



j8I' 2 . 



6P 



/31'2 6P 



w. 



Differ- 





served. 



lated. 



served. 



lated. 



a 



a 



a a 





ence. 



106 



3147 



2-916 



4-680 



4772 23-62 



103-00 



126-62 



130-75 



+ 413 



212 



2-958 



2711 



4-365 



4-475 



20-87 



89-56 



110-43 



12306 



+ 1263 



4-26 



2447 



2-378 



4-267 



4-254 



14-31 



85-62 



99-93 



99-44 



- 0-49 



6-36 



2101 



2117 



3-899 



3-945 



1050 



7150 



82-00 



83-69 



+ 1-69 



8-48 



1-833 



1-908 



3-865 



3-918 



8-00 



66-06 



74-06 



80-18 



+ 612 



1272 



1-509 



1-594 



3-748 



3767 



5-44 



58-81 



64-25 



72-18 



4- 7-93 



22-82 



1075 



1144 



3-537 



3605 



275 



58-06 



60-81 



63-87 



+ 3-06 



3272 



0809 



0-896 



3-513 



3-575 



1-81 



5612 



57-93 



60-56 



+ 2-63 



5172 



0648 



0-633 



3-455 



3-510 



100 



59-62 



60-62 



58-94 



- 1-68 



81-22 



0-459 



0-435 



3-560 



3-586 



0-50 



60-37 



60-87 



6100 



+ 013 



Condenser. — When the experiments are made without usingthe con- 

 denser, sparks are seen to pass in the contact-breaker between the 

 platinum point and the mercury. These are due to the extra current 

 produced at each breaking of the circuit; its variations are indicated by 

 the lustre and noise of these sparks. Now they are feeble if the 

 resistance added to the induced coil is small ; they increase 

 with to a maximum when = oo (that is, when the coil is open). 

 Hence the extra current becomes small or increases with 0. 



These sparks have two inconveniences : first, they divide the 

 mercury, make the alcohol turbid, and increase its conducting-power; 

 then also they expend the heat of the pile. The condenser remedies 

 these defects, annuls the sparks, prevents the turbidity of the liquid 

 and the increase of its conductivity ; it also annuls the heat, which is 

 transported from the cup, where it is not measurable, into the inte- 

 rior of the condenser, where it can be measured. 



The following is the working of the instrument. At the moment 

 of rupture the extra current has two paths — one by the contact- 

 breaker and the battery, the other by the condenser ; this latter pre- 

 sents least resistance ; this current collects there in the form of two 

 charges of high tension, positive and negative, which condense on 

 the armatures as long as it lasts, and recombine through the coil 



