.S7A' \\-ll.l.lA.\l SIEMENS, l-.R.S. 239 



Society on the l(!th January, 1870, in reference to certain means 

 uf measuring and regulating electric currents. This thin strip or 

 \viiv is in metallic connection at one end with oneof the suspension 

 rods connected with the positive pole, and at the other with one 

 of the suspension rods connected with the negative pole, being led 

 up and down over pulleys in order to produce a total resistance of 

 from L'II to : '.u ohms. The tension on this wire produced by balance 

 weights prevents the carbon points from coming into contact with 

 each other. "Whenever the current is turned on, the iron strip 

 becomes heated and elongates, allowing the carbons to approach 

 each other. From the moment they touch the arc is formed, 

 ciuising less current to pass through the iron strip or by pass, 

 which consequently contracts on cooling, and causes the carbon 

 poles to separate, thus effecting the proper regulation of the arc. 



In its application to horticulture, a metallic parabolic reflector 

 of considerable diameter is placed over the luminous centre, in 

 order to reflect downwards all the rays of light and heat which 

 would otherwise pass upward, an arrangement which may be 

 advantageously carried out in these lamps as used for illumination 

 when placed at a considerable elevation above the ground. 



The horizontal carbon-holders may be made of considerable 

 length, and one rod of carbon may be made to follow up the 

 preceding one, in order to obtain a continuous action of the lamp ; 

 it is necessary, however, to join the one carbon to the succeeding 

 one, by drilling the ends and introducing a short piece of steel 

 connecting-wire between the two. The metallic connection be- 

 tween the carbon and the carbon-holder is effected by contact 

 springs and levers, the latter of which may be so arranged that, 

 when through some mistake carbons have not been supplied to a 

 lamp at the proper time, the contact lever in tipping up, short- 

 circuits the working current, causing the extinguishment of the 

 lamp, without stopping the working of other lamps within the 

 same electrical circuit. 



Further experiments have shown that the colour of flowers and 

 fruit subjected to continued electric light is much intensified. "We 

 have been able to bring strawberries to ripeness by mean? of the 

 electric light fully a fortnight before the usual time, such fruit 

 being remarkable for its colour and aromatic flavour. But it 

 seems that the formation of sugar is not dependent upon this con- 



