ON THE INCANDESCENCE OF METALLIC WIRES. 433 
gotten and partly used, like the anecdote of Charles the Second’s 
fish, as a warning against all hypothesis. Since Van Marum 
with every assistance made a series of valuable experiments 
upon the effects of an increased power of electricity, we have 
contented ourselves with enumerating these experiments one 
after the other. Indeed, we have gone a step beyond Van 
Marum. When the Dutch philosopher expresses his astonish- 
ment at some of the effects of electricity, he means to hint, that 
he has sought for some connexion between them, and that some 
band of union should be sought for. In the manuals of natural 
philosophy, however, it is stated, without further remark, that 
electricity causes heating effects, amongst which are reckoned 
the incandescence, melting, and reducing to dust of the metals; 
that it also exerts mechanical action, on which occasion the rend- 
ing of imperfect conductors is mentioned; and, lastly, that it 
occasions chemical decompositions. Such a division of the phe- 
nomena is not at all suited to convey a right impression of the 
mode of action of the electrical discharge, and has indeed pre- 
vented us for a long time from forming a correct idea of what 
really does take place. For, so long as incandescence and fusion 
by means of electricity were considered as the direct result of 
the heat excited, it appeared sufficient to examine the laws of 
the electrical excitation of heat between any two points on the 
scale of temperature, which, as it was necessary to use the air 
thermometer, could not be chosen for a range of temperature 
widely differing from that of the air. 
I have submitted to fresh examination the effect of electrical 
discharges gradually increasing in power upon wires, and have 
found that, for a discharge of a certain power, the appearances 
of heat and mechanical action are simultaneous, and that there- 
fore Franklin’s hypothesis of cold fusion is not further from the 
truth than the one commonly adopted of hot fusion. At the 
same time I discovered a difference in the manner in which 
electricity was propagated in good conductors; it appeared 
to me worthy of notice, as it explains many electrical actions 
which have hitherto been isolated facts. In the following ex- 
tract those experiments are described, the wires of which have 
been preserved fixed upon paper with amber varnish. It ap- 
peared to me that a drawing of these specimens could not be 
executed with sufficient accuracy to increase the clearness of the 
description. 
