1883.] Electric Discharge with Chloride of Silver Battery. 151 



me that the velocity of the wave between Glalle and Aden was 378 miles 

 an hour, and the lengths of the great waves from 287 to 630 miles. 



Postscript, December 15. — Since the abo^e was read before the Royal 

 Society, a copy of the barometric trace from New York has been 

 received, which shows disturbances very similar to those recorded at 

 Toronto, and at times which are quite in accordance with the con elu- 

 sions stated in the paper. 



III. " Experimental Researches on the Electric Discharge with 

 the Chloride of Silver Battery." By Warrex De La 

 Rue, M.A., D.C.L., Ph.D., F.R.S., and Hugo W. Muller, 

 Ph.D., F.R.S. Received December 5, 1883. 



Second Postsceipt to Part IV. " Phil. Trans.," Part II, vol. 174. 



Striking Distance. 



In a postscript to Part IV of our researches,* we stated that, with 

 14,400 cells, partly of the rod form, partly of the chloride-in-pow der 

 form, the length of the spark between paraboloidal points was 0'7 inc h 

 (17"8 millims.), and between a point and disk 0"62 inch (15*7 millims.), 

 and that it does not appear, therefore, that the law of the spark being 

 as the square of the number of cells holds good beyond a certain 

 number. 



These results were obtained at the Royal Institution; since the 

 removal of the battery to our laboratory we had not, at the date of 

 the postscript to Part IV of our researches, charged up the whole of 

 it. Recently, however, we have put the battery in thorough order, 

 by scraping the zinc rodsf of the cells already charged up and added 

 newly made up cells to bring up the total to 15,000 cells, all of the 

 rod form. 



Having the whole 15,000 cells in perfect order, we thought that it 

 would be desirable to make fresh determinations of the striking dis- 

 tance, increasing the potential a thousand cells at a time, between two 

 very slightly convex disks (planes), a point and disk, and two para- 

 boloidal points. These points are one-eighth of an inch (3*175 millims.) 

 in diameter, and three-eighths of an inch (9'525 millims.) long. In 

 the case of a point and disk, the point was like one of those used for 



* " Phil. Trans.," Part II, vol. 174, p. 725, separate copy p. 249. 



f We are at present making experiments in order to prevent the deposit of oxy- 

 chloride of zinc on the zinc rods by covering the charging fluid with a layer of 

 paraffin oil. 



VOL. XXXVI. M 



