August 1, 1898.] Supplement to the " Tropical Agriculturist." 
145 
collapse of fibre, and lateral adhesion of the fibres. 
Where a stick of wood is tested, more of these 
forms of resistance can be isolated and tested 
separately, and in every kind of failure two or 
more are represented. 
Since the strength of the fibres in adhesion 
is very much less than in tension and compi-es- 
siou, adhesion enters into nearly every test as 
an important factor.. Thus, if a piece of wood 
consisting of several fibres is tested in tension, 
the fibie would probably not break at all, but 
be merely pulled ouf, the failure, as far as they 
are concerned, being due to lack of adhesion 
and not to a lack of tensile strength. Every 
tension test presents numerous cases of this kind, 
the broken fibres presenting no even fracture, 
but being splintered and drawn out, especially if 
the wood is good. 
In the same way when a piece of wood is 
compressed lengthwise, some fibres badly situ- 
ated with regard to the action of the load 
collapse, or else crush into their neighbours, 
and immediately a breach develops into which 
fibre after fibre falls, the breach spreading 
from this point ; and the whole mass of fibres, 
now no longer adhering in this plane, behave 
as a great number of separate fine strands — they 
" buckle," and the piece fails. 
Bending is a compound test of compression 
on the upper (concave) side of the beam, and 
tension on the lower (convex), and numerically 
stands between these two, that is to say, if a stick 
breaks in bending, whether it break first on the 
upper side (in compression) or on the lower side (in 
tension), the bending strength, as commonly 
stated, is neither equal to the compression strength 
nor to the tension strength, but lies bet wen the 
two. Here, as in the case cited, adhesion forms 
one of the factors, since at failure part of the 
rupture consists in a separation of fibres 
Shearing along the fibre is simply a test in 
adhesion, where the force acts in a line parallel 
to the fibre, and the values in shearing wherever 
tested agree witli those of test in '' transverse 
tension," as the test of adhesion may be termed. 
♦ 
THE CASTOR OIL PLANT. 
This plant, known botanically as Ricinus Com- 
munis, is supposed to be native to India, though 
somea uthorities make it of African origin. It is 
now extensively cultivated in India, the southern 
States of America, and even the warmer parts 
of Europe. It stands wide ranges of climate, and 
in the tropics grows from sea-level to a height 
of 0,000 feet- In temperate climates (where it 
grows in the summer) it is an annual, but in the 
tropics it becomes a small perennial tree. 
The best soil is a rich well-drained sandy or 
clayey loam ; light loose sandy, and wet heavy 
soils are not suitable. The plant is said to 
improve the fertility of soils on which it is grown, 
biit this is a mistaken idea as the seeds contain 
mucli nitrogen, potash and phosphoric acid, and 
thus heavy crops would remove considerable 
quantities of these substances from the soil- The 
plant has many roots which penetrate deeply, 
and, therefore, by their decay tliey would open 
channels for the penetration of the atmosphere, 
and thus increase the valuable constituents of 
and add organic matter to the land, thereby 
temporarily increasing the available quantity of 
plant food, and so the error of imagining that 
the plant enriches the soil may be explained in 
this way. 
Plants are propagated by seeds which are sown 
in the fields. The laud is cleared and piepared 
in the usual way ; deep tillage and subsequent 
harrowing being necessary to render the soil open 
and free, so that the roots can penetrate easily. 
Before sowing, hot water should be poured over 
the seeds, and they may, with advantage, be left 
to soak in the water for twenty-four hours. Then 
the seeds are planted at distances of six feet by 
six, or eight feet by eight, in good rich land. 
The best time for sowing is just before the rainy 
season commences. Four seeds should be planted 
in each hole, at the distance of six inches from 
each other ; and, when the plants are from six 
to ten inches high, all but the strongest seedling 
should be pulled up, The seeds will usually 
germinate in about ten days, and the plant will 
grow rapidly, and commence to bear in four 
months from the time of sowing. The ground 
will have to be kept clear of weeds, and the 
plants may with advantage be moulded up occa- 
sionally. As the object of the planter is to 
produce trees with many fruit-bearing branches, 
it will be necessary to nip back the main stem 
when it is making too rapid growth, otherwise 
long lanky stems with few flowering spikes will 
result. The castor oil plant has few enemies, for 
most insects shun it ; and for this reason it has 
been recommended in cases of insect blights on 
other plants, that castor oil bushes should be 
planted at intervals in the affected fields. In 
older plants, however, the bark of the stem 
becomes attacked with various insects, such as 
the scale blight. Coccus, and the mite, Acarus. 
Should these pests appear to injure the trees, 
they may be killed \sy applying lime wash or 
kerosine oil emulsion to the affected stems with 
a brush. 
There are two principal kinds of castor oil seeds 
cultivated — the large and the small varieties. 
The large seeds yield from 25 to 30 per cent, of 
oil, but the oil is of an inferior quality, and it is 
used only for lighting and lubricating purposes. 
The small seeds give from 38 to 40 per cent, oil, 
which is of a finer quality, and this variety is 
the one from which the medicinal cold-drawn oil 
is obtained. The plants commence to bear at the 
fourth month, and the crops Mill become larger 
as the trees increase in size. In India, sometimes 
a vield of 15 lb. of seed is obtained from single 
trees ; and in the United States it is reckoned 
that from fifteen to twenty-five bushels are got 
from an acre of land under castor seed cultivation. 
There is a ready sale for the cleaned seed in the 
American and European markets. In the United 
States, the seeds are sold by the bushel of 46 lb , 
and the produce may be shipped in bags or in 
barrels. 
In harvesting, the spikes are gathered as soon 
as the capsules commence to turn brown ; for, 
if they were left on the trees to ripen tlioroughly, 
the crops would be lost as the capsules burst open 
suddenly with some force and scatter the seed to 
wide distances- The spikes, when cut off, are 
