“k 
et 
d3T (Day. 
1883.) 
‘ | Red Oak 
Live Oak, | nied 
Bs ee ae +, \\(probably either @. 
(Quercus virens, Ait) rubra or Q. palustris.) 
| 
Lbs. | Lbs. 
The five pieces tested with 1265 440 
900 | 490 
the rays running in the direc- 1250 | 480 
960 | 425 
tion of the tension broke at. . 1225 ATO 
AYVG@THZO. s ne. 00s 1120 | 461 
The five pieces tested with 500 245 
the rays running perpendicu- ce a 
es ee a OE 4 55 
lar to the direction of tension 590 | 190 
DPORG: Btiiet NT sete ste ius 680 | 160 
Average. ssn sed. 592 | 189 
The surprising fact will be observed that in the Live Oak the force re- 
quired to overcome the lateral adhesion of the fibres when reinforced by 
medullary rays is almost, and in the Red Oak more than twice that re- 
quired when not so reinforced, Similar experiments upon Buttonwood 
(Platanus occidentalis, L.) would probably show an equal, if not greater, 
difference, While Hemlock, Pine, Tulip-Poplar or other woods with 
weak rays, it is but reasonable to expect, would show but slight differences 
in the two directions. 
In view of the above results it is easy to see that resistance to splitting, 
although usually ascribed to ‘crookedness of grain,’’ is also in a large 
measure due to the binding action of the rays. Where, however, we 
have both of these qualities present, we find a wood admirably adapted 
for certain purposes, as for example the manufacture of hubs. Hence it 
is that Rock Elm (Ulmus racemosa) and Black Gum or Tupelo (Nyssa 
multiflora, Wang.), in both of which abundant rays are found coupled with 
reat contortion of fibres, are much in demand by hub makers. 
In Lignum Vite (Guatacum officinale) the crossing of the fibres of dif- 
ferent layers is very apparent, and in a specimen of Black Gum, fibres 
were found which deviated from the vertical as much as ten times their 
breadth in their own length. 
Plates III and LY are given as illustrations of the statement concerning 
the resistance to splitting or wedging made above. ‘The upper half of 
Plate III shows 4 transverse section of Buttonwood, enlarged 125 times. 
The drawing is made from the wood of the butt of a tree which portion 
presented such great resistance to wedging that it was finally reduced to 
o 
o 
manageable size by the use of gunpowder, In it are seen the abundance 
PROC, AMER, PHILOS. 800, XXI, 114.2Q. PRINTED FEBRUARY 1, 1884, 
