512 



M. B. W. Feddersen on the Electric Spark. 



With the smaller discharge (.240 milliras. reduced length of 

 water column) I read oflf directly on the nonius the alteration iu 

 the distance of discharge of the two discharges. With the greatest 

 resistance this altci-ation was too small. I was compelled there- 

 fore to allow several (3 to 6) discharges to occur, whereby the 

 diminution found in the distfmce. of discharge of the two dis- 

 charges — the small numbers under B in the iirst Table — assumed 

 more the nature of a mean value. From three to six mean 

 values, observed in this way with about the same charge, were 

 then combined to a single mean value from which the relation 

 in question was reckoned. 



For the greatest resistance, with which the charge in the jar 

 was very gradually increased, I have given each observation se- 

 parately, while for the less resistance they are collected into four 

 groups ; for in one group the charges employed differed incon- 

 siderably. Accordingly, in the accompanying Table, by every 



group from which the greatest and least values for j and the 



mean value are given alone, there is given also the number of the 

 observations which the group comprises. 



scription of my observations, aud foimdeil on a few exi)ei'imeuts, because a 

 reduction of errors of observation can only be admitted when by such re- 

 duction no new unknown en-ors can be introduced into the calculation. 



