Pe aE ia a aah a a LD ee a i kg ue oe 
M. C. Ihlseng— Velocity of Sound in Wood. 129 
TABLE III. 
eg Kundt’s Method. | Graphic Method. ‘Didurenta. 
Velocity V. | Probable Error. i Velocity V’. | Probable Error. 
1 3849-28 Mm. 25M. 3785°3 M. Bel MM. 64:0 M. 
2 4061°56 2°19 4024.3 5°62 37°26 
3 3934°49 4°35 3870.5 5°51 64°0 
6 4985°05 10°30 4896.7 9°56 88°35 
7 5278-59 9°69 5225.3 3°37 §3°29 
13 4753°02 2°88 4715.3 5°45 37°72 
23 4326°36 2°14 4265.6 7-88 60°76 
24 3950-90 3°66 3871.2 6°64 19°7 
The first determinations were on the comparison between 
the graphic and Kundt’s method. To this end an experiment 
was made by combining both methods, thus: while the rod 
was urging the air column into synchronous action by means 
of the cork (Kundt’s method), it sa a cones revistered, 
with its pen, the rate of its vibration. The results obtained by 
this double method should, of course, agree, as both the motions 
originate from the same source. They \ were found, however, to 
differ as shown in the annexed table. 
These values are averages of fifteen observations. A glance 
at this table shows that the air method gives results which are 
invariably higher than the graphic method, the difference 
between ‘the numbers being much larger than the sum of the 
errors in the two cases. This may be due to the fact of Kundt 
using too large a pir for the correction for moisture and 
minimum. Thus, wy hese: the velocities on the supposition 
that the air was pay dry we obtain the following results 
which are still too h 
Rods. Calculated Velocity. Diff. from Graphic Method. 
3838°04 M.” 3°74 
2 4038 42 _ f+ 14°12 
3 3922°53 + 52°03 
6 4966°34 + 69°64 
7 5263-93 + 38°63 
13 4728°40 + 13°10 
23 4311°05 + 45°45 
24 3939°01 + 67°81 
These comparisons show, it would seem, that the tendency 
of Kundt’s methods, at least as used to give 
bean. which were somewhat higher than they should have 
een 
he above it may be added that in these experiments on 
Ka s method, the stopper J, figure 1, was placed ata node, 
thus making an air column in the tube which was in unison 
