Mr. Halliwell on tlie History of the Inductive Sciences. 461 



all appearance perpetual. I thought for some time it might 

 be possible to procure similar perpetual currents, by com- 

 pound thermo-electric arrangements. Fig. 8 will serve to 

 show the character of these combinations, and also the cause 

 of their failure. Let a, 6, c, be wires of three different metals 

 soldered together so as to form a triangle. Now if these 

 metals were selected, so that a and h could form a more 

 powerful thermo-electric pair than a and c, or h and c, it 

 might be expected that at all temperatures an incessant cur- 

 rent would run round the system. Such, however, will not 

 be found to be the case. In effect, any one of these three 

 serves simply as a connecting solder to the other two, and 

 hence no current is excited ; for the ends that have the third 

 metal between them, although that metal intervenes, are un- 

 der exactly the same condition as the other ends which are 

 in contact. 



5. Thermo-electric currents, evolved by pairs of different 

 metals, do not appear to differ specifically. As different gases 

 during combustion burn with differently-coloured flames, and 

 as different sources of caloric evolve rays of heat which are 

 absorbed differently by different media, it might be expected 

 that a pair of wires of copper and platina would give out a 

 current of electricity unlike that of iron and palladium. I have 

 made many trials on this point, adjusting a wire of copper and 

 one of lead to each other, so as to stop equal quantities of 

 electricity flowing from a pair of copper and platina, the 

 galvanometer needles being brought to the same point, 

 whether the long wire of copper or the short wire of lead 

 was employed. But, in the case of every combination which 

 I tried, these two wires acted alike, nor could I ever evolve a 

 current which would pass vvith more or less absorption along 

 the lead than along the copper. 



LXVIII. Illustrations of the History of the Inductive Sciences. 

 No. I. The Reception of the Co-pernican Theory in England, 

 By J. O. Halliwell, Esq., F.R.S., F.R.A.S,, F.S.A., 

 M.R.S.L., <§'c. of Jesus College, Cambridge.-''' 



npYiE most zealous reader would not require, nor the most 

 -^ enthusiastic inquirer expect, to find the results of new 

 and deep antiquarian research in so comprehensive a work as 

 that by Professor Whewell on the Flistory of die Inductive 

 Sciences ; much less would any one for a moment consider 

 the credit of that eminently distinguished author in any de- 



* Communicated by the Author, 



