H. A. Rowland—Absolute Unit of Electrical Resistance. 437 
Should we reject the quantity 34-831 in the third experiment 
so as to make the mean result of that experiment 34-744 instead 
of 34:778, we should obtain as a mean result of the whole 
34°7156+°0053, 
which has a less probable error than when the above observa- 
tion is retained. ‘The number of plus and minus errors are also 
more nearly equal and the greatest difference from the mean 1 
part in 1100. However the two results do not differ more than 
1 part in 10,000. 
We shall take 
earth quad. Z 
R=34°719-+-'007 iena at.17°C. 
as the final result. 
Discussion. 
On glancing over the table we see that the number of nega- 
tive errors greatly exceed the number of positive, but, if we 
take only the four errors which are greater than 1 part in 5,000, 
we shall find two of them negative and two positive. 
Combining the results with the different coils we have 
A ond 6... Se 34°696-+°005 
A sed 2 ee 34°744-+4 ‘011 
B and C 34°716-+- 007 
Had we no other results to go by, we might suppose that the 
value of M might not have been found as exactly for these 
coils as we have supposed them to be. But if we include the 
eager: results rejected on account of the imperfect circle 
ll find 
used, we sha 
Aie0 Bs tee 34°704+°006 
mane t oe as 34°718+017 
Sie 84°758-+ ‘016 
which has the greatest error in an entirely different place. _ 
From the first series the probable error of each determination 
errors which are about equal to +;,'s5, the real probable error 
of M must be about 1 part in 2,500. The 
tions is however too small for an exact estimate of the probable 
errors. 
Taking the results with currents of different strengths, we 
find 
For strongest current.....--.-++--++> 34716 
“ medium Bas Sis 6s oe so 84-715 
ie. lt. ee mes Ree Sek eee 34-727 
which are almost perfectly accordant. Taking the results from 
the method of recoil and the ordinary method, we find 
For ordinary method....... Sue acne 34726010 
“ method of recoil.......---++++-> 84:705 + 006 
