226 
DR. TYNDALL ON MOLECULAR INFLUENCES. 
To enable the eye to detect, at once, the law of action established by the experi- 
ments, we will present the results in a more condensed form. 
Deflections. 
Description of wood. 
I. 
Parallel 
to fibre. 
II. 
Perpendi- 
cular to 
fibre and 
parallel to 
ligneous 
layers. 
III. 1 
Perpendi- 
cular to 
fibre and to 
ligneous 
layers. 
Description of wood. 
I. 
Parallel 
to fibre. 
11. ! 
Perpendi- 
cular to ; 
fibre and f 
parallel to 
ligneous ^ 
layers. ! 
III. 
Perpendi- 
cular to 
ibre and to 
ligneous 
layers. 
1 American Birch 
O 
35 
O 
9-0 
O 
11-0 
28 Botany Bay Oak 
28 
O ' 
9-9 
C 
12-4 
34 
9-5 
11-0 
29 Cocoa-wood 
28 
11-9 
13‘6 
3 Beech 
33 
8-8 
10-8 
30 Madagascar Red-wood 
28 
10-7 1 
1P3 
4 Coromandel-wood 
33 
9-8 
12-3 
31 Sandal- wood 
28 
10-0 1 
1 P7 
33 
10-0 
11*0 
32 Tulip-wood 
28 
IPO 
12-1 
33 
10-0 
11*4 
33 Camphor-wood 
28 
8-6 ; 
10-0 
32 
9-5 
10-5 
34 Olive-tree 
28 
10-5 • 
13-2 
8 Bird’s-Eye Maple 
31 
11-0 
12-0 
35 Gaffle-Deal 
27 
10-0 
IPO 
31 
10*6 
12-1 
36 Ash 
27 
9m 
1 1*D 
31 
8-2 
10-0 
37 Green Ebony 
27 
10-5 
12*2 
31 
9‘9 
12-0 
27 
8-0 
9-4 
31 
1 1-1 
12-1 
i 39 Apple-tree 
26 
10-0 
12-5 
31 
9‘9 
12-4 
40 Cam-wood 
26 
13-4 
15-0 
31 
10-4 
12-6 
41 Iron-wood 
26 
10-2 
12-4 
30 
10-5 
12-5 
1 42 Chestnut 
26 
10-1 
11-5 
30 
11-9 
12-3 
43 Sycamore 
26 
10-6 
12-2 
30 
9*2 
11-0 
1 
! 44 Spruce Fir 
25 
1P8 
12-5 
18 Locust- wood 
30 
10-0 
11-0 
1 45 Honduras Mahogany 
25 
9-0 
10-0 
30 
10-3 
11-2 
46 Brazil-wood 
25 
1P9 
13'9 
30 
10-7 
11-7 
47 Yew 
24 
IPO 
12-0 
30 
10*3 
11-7 
48 Elm 
24 
10-0 
1P5 
20 
10-0 
• 12-0 
49 Plane-tree 
24 
10-0 
12-0 
23 T.aTch 
29 
10-0 
11-0 
50 Portugal Laurel 
24 
10-0 
11’5 
29 
IM 
13*1 
51 Bullet-wood 
24 
10-0 
1 IP/ 
2.5 Crrepn-heart 
29 
11-4 
12-6 
52 Spanish Mahogany .. 
23 
1P5 
: 12-5 
28 
11-0 
13-0 
53 Scotch Fir 
22 
10-0 
12-0 
27 Drooping Ash 
28 
11-0 
12-0 
54 Laurel 
22 
12-0 
1 15-0 
The above table furnishes us with the fullest corroboration of the result arrived at 
by De la Rive and DeCandolle, regarding the superior conductivity of the wood in 
the direction of the fibre. Evidence is also afforded as to how little mere density 
affects the velocity of transmission. There appears to be neither law nor general 
rule here. American Birch, a comparatively light wood, possesses undoubtedly a 
higher transmissive power than any other in the list — a result which has been esta- 
blished by numerous experiments, although but one appears cited in the table. Iron- 
wood, on the contrary, with a specific gravity of T426, stands low. Again, Oak and 
Coromandel-wood, — -the latter so hard and dense that it is used for sharp war-instru- 
ments by savage tribes, — stand near the head of the list, while Scotch Fir and other 
light woods stand low. 
We further find that the lateral conductivity bears no definite ratio to the longitu- 
dinal conductivity. Indeed the tendency appears to be that those woods which 
possess the lowest power of transmission, along the fibre, possess the highest power 
