TIMBER. 
N. 
b. 
d. 
1 
V- 
m. 
The ends lying loose. ' 
1 
1 
1 
18 
C 400) 
< 415^ 
( 405) 
406 
2 
1 
1 
18 
f 600) 
< 600^ 
( 624) 
608 
The ends firmly fixed. 
, ^ 
2 
A 
-L 
18 
f 810) 
( 812) 
805 
1580 
Loose. 
4 
1 
2 
18 
f 1570 ) 
^ 1580 ^ 
(1590) 
Loose. 
5 
1 
1 
36 
C 185) 
< 195 > 
( 180) 
187 
Loose. ' 
6 
1 
1 
36 
f 285) 
< 280^ 
( 285) 
283 
Fixed. 
7 
2 
2 
36 
f 1550 ) 
1620 V 
(1585) 
1585 
Loose. 
8 
1| 
36 
f 1665 ) 
^ 1675 > 
( 1640) 
1660 
f 
Loose. 
By comparing Experiments 1 and 3, 
the strength appears proportional to the 
breadth. Experiments 3 and 4, show the 
strength proportional to the square of the 
depth. Experiments 1 and 5, show the 
strength nearly in the inverse proportion of 
the lengths, but wi'di a sensible deficiency 
in the longer pieces. Experiments 5 and 7, 
show the strengths proportional to the 
breadths and the square of the depths. Ex- 
periments 1 and 7, show the same thing, 
conipounded with the inverse proportion of 
the length ; the deficiency relative to the 
length is not so remarkable here. Experi- 
ments 1 and 2, and Expeiiments 5 and 6, 
show the increase of strength, by fastening 
the ends, to be in the proportion of 2 to 3. 
The theery gives the proportion of 2 to 4. 
But a diiference ia the manner of fixing 
may produce this deviation from the theory, 
which only supposed them to be held down 
at places beyond the props, as when a joist 
is held in the walls, and also rests on two 
pillars between the walls. We shall here 
give an abstract of M. Buffon’s expert- 
ments. He relates a great number which 
he had prosecuted during two years on 
small battens. He found that the odds of 
a single layer, or part of a layer, more or 
less, or even a different disposition of them, 
had such influence that he was obliged to 
abandon this method, and to have recourse 
to the largest beams that he was able to 
break. The following table exhibits one 
series of experiments on bars of sound 
oak, clear of knots, and four inches square. 
This is a specimen of alt the rest. Column 1, 
is the length of the bar in feet clear between 
the supports. Column 2, is the weight of the 
bar (the second day after it was felled) in 
pounds. Two bars were tried of each 
length. Each of the first three pairs con- 
sisted of two cuts of the same tree. The 
one next the root was always found the 
hfaviest, stiffest, and strongest. Indeed 
M. Buffon says, that this was invariably 
true, that the heaviest was always the 
strongest ; and he recommends it as a sure 
rule for the choice of timber. He finds 
that this is always the case when the timber 
has grown vigorously, forming very thick 
annual layers. But he also observes, that 
