678 PROFESSOR THOMSON ON THE ELECTRO-DYNAMIC QUALITIES OF METALS. 
57 . The average progress towards the final eflfect of a reversal, as indicated by the 
numbers at the ends of these Tables, is exhibited graphically for the copper conductor 
in the different states in which it was used in the experiments, in the following 
Diagram, along with the curve exhibiting the corresponding reverse eflfect in the iron 
conductor. 
The uppermost curve represents the results of three experiments with the Iron con- 
ductor (thirty slips), the points marked * representing the mean of three days’ observa- 
tion, and the points marked that of two days’ observation. The lowest curve 
represents the results of three experiments with the Copper conductor (thirteen slips), 
the points marked V denoting three days’, and the simple dots • two days’ observa- 
tion. The middle curve represents three experiments with the Copper conductor (two 
slips), the points marked O denoting the mean of three days’ observation. 
Fig. 4. 
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8 
58. The diminution of the conducting power in the copper conductor had so 
markedly augmented the looked-for indication of a convective eflfect, that it was to 
be expected a corresponding augmentation might be obtained by treating the iron 
conductor similarly. Instead, however, of cutting up the iron conductor, which, as 
it stood, possessed sensibility enough to give a very decided result, I prepared a new 
iron conduetor on a much smaller scale. It appeared that the smaller the conduct- 
ing power for the same strength of current, and the same diflferenee of temperatures 
between hot and cold, the greater would be the indication of convective eflfect ; and 
the greatest indication would therefore be obtained by \ Continued after Table VII.] 
