664 ALEXANDER MACFARLANE ON THE 
TABLE X XJI.—Pressure Curve, 15th June 1877. Longer Spark. Dielectric, 
Air. Electrodes, large discs. Length of spark, 1 centimetre. 
Equation, V =-080620 ./ {p? + 219-84}. 
Pressure in Observed Mean Diff. of Calculated 
mm. of Deflection. Zero. Diff. of eo f P soe in Diff. of Difference. 
Mercury. n. ni, Potential. Ca SO Sue: Potential. vi_v. 
1 Potential. measure. 
p. ni—n. vi. i 

485 505 20 
20 486 ‘ 19 20-4 5:59 5-58 40-01 
484 506 22 
478 507 29 
40 478 : 29 29:3 8-03 8-22 ~0-19 
477 ‘s 30 
470 : 37 
60 468 506 38 38 10-41 10-45 ~0-04 
468 ‘ 38 
459 : 47 
80 461 45 46 12:60 12-49 +011 
460 i 46 
ff 455 508 53 
100 453 507 Bd 53 1452 14-42 +010 
U| 455 . 52 
444 508 64 
120 444 507 63 63 17-26 16-28 40-98 
444 : 63 
435 ‘ 72 
140 435 i 72 71 19-45 1810 41:35 
436 ee 71x 
423 84 
160 44 i s3x |b 93 29-74 19:87 42:87 
423 . 84 
ff 418 508 90 
180 429 509 87 84 23-01 21:63 4138 
U| 425 t 84 x 
408 500 92 |) 
200 408 502 04 89 24-38 23:36 4102 
415 504 89x |f 
| 268 513 | 245 . 
740 Nae cae a | see beds 67-94 67-94 0:00 



