II. REGULATORS (PLACE AND TIME). 317 



13 4:3 a. Specimens of Wire for Electric Apparatus. 



1. Copper wires, covered with gutta-percha (1, 2, 25). 



2. Copper wires, covered with gutta-percha and cotton (3). 



3. Copper wires, covered with cotton (4, 5, 6, 9, 11, 12, 13, 14, 

 26). 



4. Copper wires, covered with silk (7, 8, 10, 15 to 23, 27). 



5. Elastic poires, with their cordons (24). 



6. Covered wires of various metals, with statement of their 

 resistance. Madame Bonis, Paris. 



1235a. Apparatus for uniting several Galvanic Elements 



into one of large surface, so as to preserve the entire strength of 

 the current by lessening the resistance. 



Imperial University of St. Petersburg. 



To effect this, two metal cylinders, each bored with seven holes parallel to 

 the axle, and fitted with screws, are used. In one cylinder, the six ends of 

 conductors connected with the positive electrodes (anodes) of the elements 

 are inserted, and in the other, the six conductors connected with the negative 

 electrodes (cathodes). The seventh hole is reserved for a conductor, the 

 section of which is equal to the total section of the six other conductors. 

 This last conductor issues from the opposite side of the cylinder. The appa- 

 ratus here described is used by Prof. Petrouchevsky in St. Petersburg. 



1345. Single Plug Key, to close or break contact for long or 

 short durations. Elliott Brothers. 



1346. Fall-hammer, to obtain perfectly equable closing of a 

 circuit. 



Prof. Engelmann, Physiological Laboratory and Ophthal- 

 mological School, Utrecht. 



On a brass prismatic lever, movable round a horizontal axis, slides the 

 bridge, a copper cover having underneath two amalgamated copper points. 

 On depressing a spring the lever falls from a nearly vertical position, and 

 plunges the bridge into two mercury vessels, movable on a horizontal slide, 

 and connected with the battery. A spring prevents the bridge from rebound- 

 ing. Velocity of fall to be regulated by moving the bridge on the lever with 

 corresponding displacement of the mercury vessels on the horizontal slide. 



The bridge being in the primary circuit of an induction apparatus, the 

 breaking is every time to be effected at another place of the circuit, before 

 lifting the bridge from the mercury, in order to prevent oxidization of the 

 mercury by the spark. 



The instrument can easily be managed with one hand. 



1347. Firing Key, f or torpedoes, &c. A simple contact key, 

 with a movable piece of vulcanite, which can be brought between 

 the two platinum contacts to prevent fatal results by accidentally 

 closing the circuit. Elliott Brothers. 



1348. Apparatus for reversing the direction of an 

 Electric Current. Used with an electro-magnetic torsion ap- 

 paratus. George Gore, F.R.8. 



(See Philosophical Transactions of the Royal Society, Vol. 164, p. 529.) 



