202 CONTINUITY. 



rely on invention being in this case, as in others, born of 

 necessity, when the necessity arises. 



I will not further pursue this subject. At a time when 

 science and civilisation cannot prevent large tracts of country 

 being irrigated by human blood in order to gratify the ambition 

 of a few restless men, it seems an over-refined sensibility to 

 occupy ourselves with providing means for our descendants in 

 the tenth generation to warm their dwellings or propel their 

 locomotives. 



Two very remarkable applications of the convertibility of 

 force have been recently attained by the experiments of Mr. 

 Wilde and Mr. Holz ; the former finds that, by conveying 

 electricity from the coils of a magneto-electric machine to an 

 electro-magnet, a considerable increase of electrical power 

 may be attained, and by applying this as a magneto-electric 

 machine to a second, and this in turn to a third electro-mag- 

 netic apparatus, the force is largely augmented. Of course, to 

 produce this increase, more mechanical force must be used at 

 each step to work the magneto-electric machines ; but provided 

 this be supplied, there hardly seems a limit to the extent to 

 which mechanical may be converted into electrical force. 



Mr. Holz has contrived a Franklinic electrical machine, in 

 which a similar principle is manifested. A varnished glass 

 plate is made to revolve in close proximity to another plate 

 having two or more pieces of card attached, which are elec- 

 trified by a bit of rubbed glass or ebonite ; the moment this is 

 effected, a resistance is felt by the operator who turns the 

 handle of the machine, and the slight temporary electrisation 

 of the card converts into a continuous flood of intense elec- 

 tricity the force supplied by the arm of the operator. 



These results offer great promise of extended application ; 

 they show that, by a mere formal disposition of matter, one 

 force may be converted into another, and that not to the 

 limited extent hitherto attained, but to an extent co-ordinate, 

 or nearly so, with the increased initial force, so that, by a mere 

 change in the arrangement of apparatus, a means of absorbing 

 and again eliminating in a new form a given force may be 

 obtained to an indefinite extent. As we may, in a not very 

 distant future, need, for the daily uses of mankind, heat, light, 



