'=/} 
Pomegranate 
Ihs. 
9,750 
Lemon 
9,250 
Tamarind 
8,750 
Fir 
Walnut 
8,130 
Pitch pine 
Quince 
6,750 
Cypress 
Poplar 
5,500 
Cedar 
Ml Muscliejibroek has given a very mi- 
nute detail of tlie experiments on the ash 
and the walnut, stating the weights which 
were required to tear asunder slips taken 
from the four sides of the tree, and on each 
side in a regular progression from the cen- 
tre to the circumference. The numbers of 
this table corresponding to these two tim- 
bers may therefore be considered as the 
average of more than fifty trials made of 
each ; and he says that all the otliers were 
made with the same care. We cannot 
therefore see any reason for not confiding in 
the results ; yet they are considerably higher 
than those given by some other writers. M. 
Pitot says, on the authority of his own ex- 
periments, and of those of M. Parent, that 
sixty pounds will just tear asunder a square 
line of sound oak, and that it will bear fifty 
jvith safety. This gives 8,640 for the utmost 
strength of a square inch, which is much in- 
ferior to Muschenbroek’s valuation. AVe 
may add to these. 
Ivory I 16,270 
Bone 5,250 
Horn 8,750 
Whalebone 7,500 
Tooth of sea-calf...., 4,075 
The reader will surely observe, tljat these 
numbers express something more than the 
utmost cofiesion ; for the weights are such 
as will very quickly, that is, in a minute or 
two, tear the rods asunder. It may be said 
in general, that two-thirds of these weights 
will sensibly impair the strength after a con- 
siderable while, and that one-half is the 
utmost that can remain suspended at them 
without risk for ever ; and it is this last 
allotment that the engineer should reckon 
upon in his constructions. There is, how- 
ever, considerable difference in this respect. 
Woods of a very straight fibre, such as fir, 
p/jll be less inipaired by any load which is 
TIMBER. 
not sufficient to break them immediately. 
According to Mr. Emerson, the load which 
may be safely suspended to an inch square 
is as follows : 
Iron 76,400 
Brass 35,600 
Hempen rope 19,600 
Ivory 15,700 
Oak, box, yew, plum- 
tree 7,8.50 
Elm, ash, beech 6,070 
Walnut, plum 5,360 
Red fir, holly, elder, 
plane, crab 5,000 
Cherry, hazle 4,760 
Alder, asp, birch, willow 4,290 
Lead 430 
Freestone : 914 
He gives us a practical rule, that a cy- 
linder whose diameter is d inches, loaded to 
one-fourth of its absolute strength, will 
carry gs follows ; 
cial. 
Iron 13.5 
Good rope 22 
Oak 14 
Fir 9 
Experiments on the transverse strength 
of bodies are easily made, and accordingly 
are very numerous, especially those made 
on timber, which is the case most common 
and most interesting. But in this great 
number of experiments there are very few 
from which we can draw much practical in- 
formation. The experiments have in gene- 
ral been made on such small scantlings, that 
the unavoidable natural inequalities bear 
too great a proportion to the strength of 
the whole piece. Accordingly, when we 
compare the experiments of different au- 
thors, we find them differ enormously, and 
even the experiinents by the same author 
are very anomalous. The completest series 
that we have yet seen is that detailed by 
Belidor in his “ Science des Ingenieurs.” 
They are contained in the following table. 
The pieces were sound, even-grained oak. 
The column b, contains the breadth of the 
pieces in inches ; the column d, contains 
their depth ; the column I, contains their 
lengths ; column p, contains the weights 
(in pounds) which broke them when hung 
on their middles ; and m is the column, 
of averages or mediums, 
