MEN 
interval between the two, the solid con- 
tents will he found. 
The contents of pyramids are measured 
by multiplying the areas of their bases by 
half their lengths ; or their lengths by half 
the areas of their bases. Cones, whose sides 
are straight, are equal to one-third the solid 
contents of cylinders, equal to them in base 
and altitude. 
Solid*, which have a certain degree of re- 
gularity, may be easily measured: thus a 
cube is computed by multiplying first its 
width by its length ; then their sum by its 
height : thus a cube, measuring four feet 
each way, would be 4 X 4 = 16 X 4 = 64. 
This is the meaning of what is called the 
cube root: see Cubic Number. Paral- 
lelopipedons, or solids of a long form, such 
as squared timbers, are measured by the 
same means : say that a timber be seven 
feet long, and at its ends be six inches by 
four. The area of either end, which is here 
considered as the base, will give 24 square 
inches, which multiplied by 84 (the number 
of inches in 7 feet) will show 2,016 solid 
inches. Divide by 1728, (the number of 
solid inches in a solid foot), and the result 
will be 1 foot 288 solid inches. But we 
have a shorter way, when, as in the above 
instance, the parts are regular multiples ; 
for 6 by 4 is the sixth part of a superficial 
foot ; consequently six feet in length of 
such a beam answers to one foot cube, and 
the remainder will shew the sixth part of a 
foot cube: so that we may indicate the 
amount, either as above, or by calling it 
1 solid foot and i. For the mensuration of 
growing timber, various modes have been 
oflfered; but we know of none more sim- 
ple than that invented by Captain William- 
son, and exemplified in his “ Mathematics 
Simplified.” 
His practice has been to fix a short bat- 
ten, at exactly 45 degrees, angular with a 
staff of about 5i feet long ; the latter be- 
ing armed with a spike to fix it in the soil, 
and having a plumb line at one corner. 
When a sight taken along the batten, (the 
statf being exactly perpendicular), points to 
the highest part of a tree, that is of the 
main trunk, measure the distance from the 
place where the statf is fixed to the plac? 
where the tree stands: the intermediate 
distance, added to the length of the staff, 
will show the height to which the timber is 
marketable. For it is evident, that, as an 
angle of 45 degrees gives equal base and 
perpendicular, so must the altitude corres- 
pondent with the distance between the 
MEN 
junction of the batten with the staff to 
the tree, and a perpendicular from the part 
cut on the tree, by the line of sight, to the 
level of that junction : the length of the 
staff must correspond with the length of 
stem below that level. We beg leave to 
refer our readers to the publication above- 
quoted for further particulars on this head, 
as well as for numerous useful hints in re- 
gard to surveying in general. See fig. 9. 
After a tree has been felled, its girth is 
usually taken at each end, and at the mid- 
dle : when there is ho particular swell, or 
that the top extremity does not suddenly 
decrease, this rule may answer well ; but 
where the irregularity is great, it is better to 
take many more girths, and summing up 
the whole, to divide their amount by the 
number of girths taken; so as to establish 
a mean measurement. Divide that mean 
measurement by 4, to find the side of a 
square to which the tree will be reduced 
when prepared for the sawyer. If the 
whole solid contents are to be estimated, 
divide by 3, instead of by 4, and taking 
the third part, thus given, for a diameter, 
act upon it as already shown, to find the 
side of a square, equal to the circle of 
which that ascertained third part is the 
diameter. 
The greatest portion of mensuration ap- 
pertains to the contents of solid bodies, or 
areas, such as hay-stacks, interiors of barns, 
granaries, &c. ; all of which come under 
the rule laid down for cubes, &c. When 
any sides fall in regularly, as in garrets, &c. 
the inclined part must be treated as a py- 
ramid, or as a quoin, (or wedge), and the 
whole be summed up together. The con- 
tents of casks, tubs, &c. are treated of un- 
der the head of Gauging, (which see), and 
that part of our subject which appertains to 
the admeasurement of lands, as also to the 
distances, heights, &c. of remote objects, 
accessible or otherwise, vvill be found under 
the head of Surveying. 
MENTHA, in botany, mint, a genus of 
the Didynamia Gymnospermia class and or- 
der. Natural order of Verticillatae or La- 
biatae. Essential character : corolla almost 
equal, four-cleft, the broader segment eraar- 
ginate: stamina upright, distant. There 
are nineteen species. M. viridis, spear- 
mint, possesses a more agreeable flavour 
than most of the others : it is generally pre- 
ferred for culinary, and some medicinal 
purposes : this herb contains a good deal of 
essential oil, as do all the other mints ; but 
of a much less agreeable odour than that of 
D d 2 
