ii. REGULATORS (Place and Time). 273 



1347. Firing Key, for 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.S. 



(See Philosophical Transactions of the Royal Society, Vol. 164, p. 520.) 



1348a. A Current-reversing Electrode, with adjoints. 



J. Teller ', Muncficn. 



This gives a more convenient change of current than the commutators so 

 far as electro-medical apparatus is concerned. 



1349. Double Reversing Key, used for cable testing. 



Elliott Brothers. 



1350. Thomson's Reversing Key, used in connexion with 

 the electrometer, for facilitating the measurement of the electro- 

 static capacity of a cable or condenser. Elliott Brothers. 



1351. Lambert's Key, constructed for charging ordischargmg 

 cables and condensers. Elliott Brothers. 



1352. Spottiswo ode's Rapid Break, for use with Intensity 

 Coils. Tisley and Spiller. 



13y means of this break the discharge in vacuum tubes can be regulated, 

 "and the motion of the stratifications diminished or rendered stationary, as 

 required. 



1353. Contact Repeater, by Captain Armstrong, R.E., to 

 repeat electric contacts of exactly similar duration. 



School of Military Engineering, Chatham. 



1354. Forms of discharge on making and closing an induc- 

 tion current. -Prof. Donders, Utrecht. 



The trial with the noematachograph to have the instant of stimulation 

 registered on the chronoscopic line by the current itself, led to the discovery : 



1. That the discharge can form a long series of sparks. 



2. That the electricity disappears more slowly when the spring rests on 



metal, more rapidly when it rests on a plate of mica, than in the form 

 of sparks making holes in the paper. (Compare Onderzoekingen 

 gedaan in het phys. labor. Ser. 2, T. III. 1870; and Wiedemann, Die 

 Lehre vom Galvanismus mid Electromagnetismus, 2 e Auflage, 1874, 

 B. II., s, 360.) 



1355. Drawings showing the patent system of lightning 

 conductors applied to buildings. J. W. Gray $ Son. 



1356. Model of mid-section of a Ship, showing the patent 

 system of lightning conductors applied to vessels in Her 

 Majesty's service, &c. J< W. Gray $ Son. 



39508 S 



