154 



Mr. R. Appleyard on Dielectr 



whatever as to a. In order to do this, the " observed " 

 results should be plotted as a curve, coordinating resistances 

 and temperatures. The length of the ordinate corresponding 

 to standard temperature on the " observed " curve is then to 

 be taken as unity, and the lengths of the ordinates at every 

 successive degree are to be expressed in terms of this unit. 

 A table can then be drawn up giving a correcting divisor cor- 

 responding to each degree. With the aid of a slide-rule such 

 a table can be completed in little more than an hour ; and it 

 is certainly more expeditious and less arbitrary than the 

 ordinary tables of dielectric corrections. As an example, I 

 have given in Table II. the divisors for paraffin-paper, from 

 33° F. to 110° F., deduced directly from the " observed" 

 curve. 



Table II. Paraffin-paper. 



(To reduce the dielectric resistance at any temperature Fahr. 

 to the corresponding dielectric resistance at 60° F., divide 

 the observed resistance by the number opposite the given 

 temperature.) 



Temp. 

 Fahr. 



Divisor. 



Temp. 

 Fahr. 







49 



Divisor. 

 1-67 



Temp. 

 Fahr. 



Divisor. 



Temp. 

 Fahr. 



Divisor. 



Temp. 

 ! Fahr. 



Divisor. 



o 

 33 



3-19 



o 

 65 



0-775 



o 



81 



0-335 



o 

 97 



0-169 



34 



3-07 



50 



162 



66 



•733 



82 



•319 



98 



•159 



35 



296 



51 



1-55 



67 



•699 



83 



•306 



99 



•153 



36 



2-87 



52 



1-46 



68 



•656 



84 



•292 



100 



•148 



37 



2-76 



53 



1-39 



69 



•625 



85 



•281 



101 



•141 



38 



2-66 



54 



1-33 



70 



•595 



86 



•270 



102 



•137 



39 



2 57 



55 



1-27 



71 



•562 



87 



•259 



103 



•133 



40 



2-48 



56 



1-20 



72 



•528 



88 



•247 



104 



•126 



41 



239 



57 



115 



73 



•501 | 



89 



•234 



105 



•119 



42 



230 



58 



1-09 



74 



•477 ! 



90 



•225 



106 



•114 



43 



2-19 



59 



104 



75 



•450 1 



91 



•216 



107 



•108 



44 



2 09 



60 



1-00 



76 



•432 



92 



•207 



108 



•105 



45 



2-00 



61 



0944 



77 



•411 ; 



93 



•198 



109 



•101 



46 



1-91 



62 



0-901 



78 



•389 



94 



•189 



110 



•099 



47 



1-82 



63 



0-858 



79 



•375 



95 



•180 







48 



1-76 



64 



0-820 



80 



•355 ! 



96 



•175 







The resistances of mica condensers at the different tempe- 

 ratures are also given on Table I. ; the curve drawn from 

 them is not so smooth as that which represents the behaviour 

 of paraffin-paper condensers ; at the colder temperatures the 

 resistance of the mica is so high that the preliminary deflexion, 

 corresponding to (a), (b), and (c), is by no means small 

 as compared to the second deflexion, due to (a), (b), (c), and 

 (d) together. The results given are the best that could be 

 obtained under the circumstances. In some ways it might 



