of determining Stream Lines and Equipotentials. 251 
The results are tabulated below : — 
50 

175 
14-9 
29-9 
•38 
32-3 
473 
75 

•64 
25 cms. 
50 „ 
•14 
Distance from base of cylinder .... 25 
„ axis „ 
Potential read from the graph as | 
decimal of unit range. ( 
Last multiplied by the actual range I 
(100°-15°) ( 
Last +15° = actual temperature . . 
Not until these numbers had been written down did I look 
at the correct values found by Byerly from the Bessel function 
series, namely : — 
29-6 47-6 71-2 25-8 
Errors of freehand determination . . -p3 — *3 — '8 +1*1 
54-4 
69-4 
11-9 
26-9 
Disregarding signs the mean of these 
which is equal to 0*74 per cent, of the range of 85°. 
errors 
o 
is *63 
