T I M 
T I M 
T I M 
the tiller is fastened to the rudder in the gun- 
room ; and to the other end there are ropes 
fastened, which pass upwards to the quarter- 
deck, where the ship is steered by means of 
a wheel. 
TILLCEA, a genus of plants of the class 
tetrandria, and the order tetragynia, and in 
the natural system ranging under the 13th or- 
der, succulent*. The calyx has three or four 
divisions; the petals are three or four, and 
equal ; the capsules three or four, and poly- 
spermous. 1 here are eight species, of which 
one only, the muscosa, is a native of Eng- 
land. The muscosa, or procumbent tilloea, 
has prostrate stems, almost erect, generally 
red, and growing longer after flowering. The 
parts of fructification are always three. The 
leaves grow in pairs, and are fleshy, ft is 
found on dry heaths in Norfolk and Suffolk, 
and flowers in May and June. 
TILLAGE See Husbandry. 
TILT-BOAT, a boat covered with a tilt, 
that is, a cloth or tarpawlin, sustained by 
hoops, for the sheltering of passengers. 
TIMBER, includes all kinds of felled 
and seasoned woods. See Acer, Betulus, 
Fr.axin.us, Quercus, Pinus, Platanus, 
Populus, Ulmus, &c. 
Of all the different kinds known in Europe, 
oak is the best for building, and even when it 
lies exposed to air and water, there is none 
equal to it. Fir- timber is however perhaps 
more generally useful than any other. It is 
used for flooring, wainscoting, and the orna- 
mental parts of building within doors. Elm is 
the next in use, especially in England and 
France; it is very tough and pliable, and 
therefore easily worked ; it does not rea- 
dily split ; and it bears driving of bolts and 
nails better than any other wood. Ash is 
chiefly used by wheelwrights and coach- 
makers, for shafts, naves, &c. Beech is also 
’“used for- many purposes ; it is very tough and 
white when young, and of great strength, 
but liable to warp very much when exposed 
to the weather, and to be worm-eaten when 
used within doors ; its greatest use is for 
planks, bedsteads, chairs, and other house- 
hold goods. Wild-chesnut timber is by 
many esteemed to be as good as oak, and 
seems -to have been much used in old build- 
ings ; but whether these trees are more scarce 
at present than formerly, or have been found 
not to answer so well as was imagined, this 
timber is now but little used. Walnut-tree 
is excellent for the joiner’s use, it being of a 
more curious brown colour than beech, and 
not so subject to the worms. The poplar, 
abel, and aspen-tree, which are very little 
different from each other, are sometimes 
used instead of fir, but mostly by turners, &c. 
The goodness of timber not only depends on 
the soil and situation in which it stands, but 
likewise on the season wherein it is felled. 
In this, people disagree very much ; some are 
for having it felled as soon as its fruit is ripe, 
others in the spring, and many in the autumn. 
But as the sap and moisture of timber are cer- 
tainly, the causes that it perishes much sooner 
than it otherwise would do, it seems evident 
that timber should be felled when there is the 
least sap in it, viz. from the time that the 
leaves begin to fall, till the trees begin to bud. 
This work usually commences about the end 
of April in England, because the bark then , 
rises most freely ; for where a quantity of 
timber is to be felled, the statute requires it J 
to be done then, for the advantage of tanning, j 
After timber has been felled and sawed, j 
it must be seasoned ; for which purpose some 
advise it to be laid up in a very dry airy j 
place, yet out of the wind and sun, or at least 
free from the extremities of either ; and that 
it may not decay, but dry evenly, they re- 
commend it to be daubed over with cow- 
dung. It must not stand upright, but lie 
all along, one piece over another, only kept ! 
apart by short blocks interposed, to prevent 
a certain mouldiness which they are other- 
wise apt to contract in sweating on one an- 
other; from which arises frequently a kind 
of fungus, especially if there are any sappy 
parts remaining. Others advise the planks 
of timber to be laid for a few days in some 
pool or running stream, in order to extract 
the sap, and afterwards to dry them in the sun 
or air. By this means, it is said, they will be 
prevented from either chopping, casting, or 
cleaving, but against shrinking there is no 
remedy. Some again are for burying them 
in the earth, others in a heat ; and some for 
scorching and seasoning them in fire, espe- 
cially piles, posts, &c. which are to stand in 
water or earth. The Venetians first found 
out the method of seasoning by lire, which is 
done after this manner: they put the piece 
to be seasoned into a strong and violent 
flame, in which they continually turn it round 
by means of an engine, and take it out when 
it is every where covered with a black coaly 
crust; when the internal part of the wood is 
so hardened, that neither earth nor water can 
damage it for a long time afterwards. 
After the planks of timber have been well 
seasoned and fixed in their places, care is to 
be taken to defend or preserve them ; to 
which the smearing them with linseed-oil, tar, 
or other oleaginous matter, contributes much. 
To measure round timber, let the mean 
circumference be found in feet and decimals 
of a foot; square it, multiply this square by 
the decimal 0.079577, and the product by 
the length. Ex. Let the mean circumference 
of a tree be 10.3 feet, and the length 24 feet. 
Then 10.3 X 10.3X0.079577X24 = 202.615, 
the number of cubical feet in the tree. The 
foundation of this rule is, that when the cir- 
cumference of a circle is 1, the area is 
0.0795774715, and that the areas of circles 
are as the squares of their circumferences. 
But the common way used by artificers 
for measuring round timber, differs much 
from this rule. They call one-fourth part of 
the circumference the girt, which is by them 
reckoned the side of a square whose area 
is equal to the area of the section of the tree ; 
they therefore square the girt, and then mul- 
tiply by the length of the tree. According to 
their method, the tree of the last example 
would be computed at 159.13 cubical feet 
only. 
For measuring hewn or square timber, the 
custom is to find the middle of the length of 
the tree, and there to measure its breadth, 
by clapping two rules to the sides of the tree, 
and measuring the distance betwixt them ; in 
like manner they measure the breadth the 
other way. If the two are found unequal, 
they are added together, and half their sum 
is taken for the true side of the square. 
Timber, strength of . “ After spending 
much time,” says Mr. Smart, “ in making 
various experiments, and comparing the re- 
5 
799 
suits with those of Buffon, Belidore, &c. the 
differences were so great, that it would be 
wasting time to enumerate them: I shall 
therefore only mention some useful observa- 
tions necessary to be known by all those me- 
chanics who use timber; and point out some 
evident errors in a table of Belidore’s, sup- 
posed to be the result of the best set of expe- 
riments ever produced in transverse strains. 
He tells us, that a bar of wood, Unity -she 
inches long, and one inch square, supported 
at the ends by two props, will break with a 
weight of 187 pounds on the middle, if it is 
loose at the ends ; but if the ends are firmly 
fixed, it will require 283 pounds to break it. 
“This appeared to me so great an error, that 
I was induced to put little or no confidence in 
many of his experiments; and, in conse- 
quence, I made two laths of fir, of the same 
dimensions, one with a strong shoulder at 
each end, to prevent its bending, which hav- 
ing firmly lixed in a frame, it carried a weight 
more than ten times greater than that which 
was loose.” 
The fibres of timber requiring so great a 
force to tear them asunder in a vertical direc- 
tion, and being easily broken by a transverse 
strain, when compared to that of a rope car- 
rying nearly an equal weight in all directions, 
opens a wide field for useful experiments. 
All timber-trees have their annual circles, or 
growths, which vary greatly according to 
the soil and exposure to the sun. The north- 
east side of the trees (being much smaller in 
the grain than the other parts, which are more 
exposed to the sun) is strongest for any co- 
lumn that has a weight to support in a ver- 
tical direction ; because its hard circles, or 
tubes, are nearer each other, and the area 
contains a greater quantity of them ; nor are 
they so liable to be compressed by the 
w'eight, or to slide past each other, as when 
they are at a greater distance. On the other’ 
hand, this part of the tree is not fit for a trans- 
verse strain; because the nearer the hard 
circles are to each other, the easier the beam 
wifi break, there being so little space between 
them, that one forms a fulcrum to break the 
other upon : but that part of a tree, the tubes 
of which are at a greater distance, or of larger 
grain, is more elastic, and requires a greater 
force to break it; because the outside fibre 
ou the convex side ; cannot snap till the next 
one is pressed upon it, which forms the ful- 
crum to break it on. It is generally observed 
in large timbers, such as masts, that the frac- 
ture is seldom on the convex, but usually on 
the concave side ; wdficb is owing to the fibres 
on the concave side being more readily 
forced past each other, and those on the 
convex being so difficult to be torn asunder, 
that they cannot snap, in consequence of the 
largeness of the segment of the circle they 
describe when on the strain. The curve de- 
scribed by the inner layers of the wood being 
so large, and indeed little less than a straight 
line, cannot form a fulcrum to break the 
outer ones upon; and as the convex side, or 
that on which the fibres are extended, ought 
to be always free from any mortise or inci- 
sion on the outside, the strength decreases-as 
it approaches the centre. 
Figs. 6, 7, 8, 9, and 10, Plate Ship-build- 
ing, describe the simple method invented 
by Mr. George Smart, of converting all 
timber that is straight, and intended for 
square beams, to great advantage in general 
