124 
knob or projecting cone or cylinder, which frequently becomes 
half an inch or more long before it falls and gives place to another. 
On the positive pole a corresponding cavity is formed, out of which 
the vaporized matter rises and collects upon the negative pole. 
The carbon thus deposited ‘is in shining, rounded masses, aggre- 
gated often like a cauliflower. It has a semi-metallic appearance, 
is harder than the charcoal, heavier, much less combustible, and 
burns away slowly when ignited in the air.’’ 
In the light of the electrical science of those days, these con- 
structions by Dr. Hare, the results obtained by their means and the 
theories which he offered in explanation of the phenomena, are all 
of very considerable interest. The principal effect of the calori- 
inotor, obviously, was to produce a great flow of heat with very . 
little electrical excitement. But experiment had pointed out that 
not only alternation of the plates but a repetition of the pairs to at 
least two was necessary to produce an intense calorific effect ; the 
quantity being as the size and the intensity as the number of the 
series. True, Davy had shown in 1808 this necessity of repetition, 
and had stated that ‘‘ the intensity increases with the number and 
the quantity with the extent of the series.’’* And Children the 
following year f had confirmed this view and elaborated it. ‘‘ The 
absolute effect of a voltaic apparatus,’’ he says, ‘‘seems to be in 
the compound ratio of the number and size of the plates, the in- 
tensity of the electricity being as the former, the quantity given 
out as the latter ; consequently regard must be had in its construction 
to the purposes for which it is designed. For experiments on per- 
fect conductors very large plates are to be preferred, asmall number 
of wicks will probably be sufficient ; but where the resistance of im- 
perfect conductors is to be overcome the combination must be great 
but the size of the plates may be small; but if quantity and inten- 
sity be both required, then a large number of large plates will be ne- 
cessary.’’ It should be remembered, moreover, that the law of Ohm 
was not enunciated until 1827,{ and that of Joule not until 1841.§ 
And, further, that we owe to these laws the simplification of the 
ideas upon the subject of the energy relations of electricity which 
existed before they were discovered. Ohm's law teaches us that the 
* Philosophical Transactions, 1808, p. 3. 
+ Ib., Vol. ix, p. 82 (1809). 
t Die galvanische Kette mathematisch bearbeitet, Berlin, 1827. 
_¢Phil. Mag., xix, p. 260 (1841). 
