EECENT PKOGEESS IN PHYSICS. 



351 



ions prove its correctness ? Certainly not. When there are two 

 onstants at our disposal it is easy to invent a whole mass of formulas 

 i/hich would serve just as well ; that is, they will accord with the few 

 liumbers observed within narrow limits, quite as closely as the limits 

 ire narrow. As a proof I propose 



<y = A + 6 log. D ; 

 [he first best arbitrary formula that occurs to me. In this formula let 

 ) denote the temperature of the secondary wire, D the axial distance 

 if the wires. Making A = 0.276, and b = 0.16, this formula will 

 {gree with Riess' observations as well as that of Knochenhauer ; as the 

 following table shows, in which the third vertical column contains 

 [he values computed by the above formula : 



I In spite of this harmony between observation and computation, this 

 I'ormula expresses just as little as Knochenhauer's, the law according 

 to which the force of the secondary current decreases with the distance 

 from the main wire. 



Knochenhauer has himself made a series of experiments to confirm 

 is formula, and by which he would show that the magnitude of a 

 ijiepends upon the conducting capacity of the main circuit,, of the sec- 

 pndary circuit, &c. The description of the modus operandi of the 

 experiments, how the wires were extended, &c., is exceedingly obscure, 

 ,and since, I think, I have proved the inaccuracy of his formula, a 

 further account of these experiments is unnecessary. 



This memoir forms the introduction to liirther researches, which 

 ■relate to the secondary current and currents in branched circuits. 

 The following are the titles of the memoir on these subjects: 



On the lateral current in divided conducting wires of the battery. — 

 j(Pog. Ann,. LX— LXX, 235.) 



I On the electrical current in divided conducting wires of the battery. 

 |(Pog. Ann., LXI, 55.) 



I On the diminution of the main current with divided conducting 

 [wires of the battery. — (Pog. Ann., LXII, 353.) 



i On the relation of the formulas which determine the development 

 [of heat by the electrical and the galvanic current. — (Pog. Ann, , LXII, 

 207.) 



Experiments on the electrical secondary current. — (Pog. Ann., 

 |LXIV, 64, and Pog. Ann., LXVI, 235.) 



; Determination of the compensating length of wire without the air 

 [thermometer.— (Pog. Ann., LXVII, 327.) 



II 



